Caution
Damage to breech assembly will result if barrel assembly is forced into barrel support assembly. c. Push the barrel assembly (1) all the way into barrel support assembly (2) until it stops. d. Rotate barrel assembly (1) in the direction of the LOCK arrow until a loud click is heard. e. Visually check to see that the LOCKED arrow on the barrel assembly (1) is aligned with the index mark on the barrel support assembly (2). f. Rotate barrel assembly (1) back and forth to make certain it is locked...
Explanation Of Columns In The Repair Parts List And Special Tools List Work Packages Continued
Maintenance Code Application Explanation C - Crew or operator maintenance done within unit AVUM maintenance. O - Unit level AVUM maintenance can remove, replace, and use the item. F - Direct support AVIM maintenance can remove, replace, and use the item. H - General support maintenance can remove, replace, and use the item. L - Specialized repair activity can remove, replace, and use the item. D - Depot can remove, replace, and use the item. Fourth Position. The maintenance code entered in the...
General
Knowing how to use this manual is very important to you. a. References are to work packages in this manual or to other publications. b. Throughout this manual, text is keyed to the illustrations by use of numbered callouts. When an item is called out in a procedure, a number in parentheses in the text corresponds with a number on the illustration. c. Each task begins with a setup sheet. It tells you what you need to do the task tools, materials, parts, and other publications. It tells you what...
Indexes
This manual is organized to help you quickly find the information you need. There are several useful indexes a. Table of Contents. The table of contents lists, in the order of presentation, all chapters, work packages, and alphabetical index and gives the page numbers where they begin. b. Alphabetical Index. This index, located at the back of the book, is an extensive subject index for the entire manual. The page numbers following each entry tell you where in the manual to find a particular...
Inspection Continued
PREFORMED PACKINGS AND GASKETS. (1) Inspect preformed packings for wear, brittleness, cracks, cuts, and damage. (2) Inspect gaskets and seals for wear, nicks, cuts, and torn or missing gasket material. Replace gasket if needed. Gaskets and seals on electrical parts may be reused. d. INSERTS. Inspect inserts for cracks, stripped or damaged threads, and loose fit. e. STUDS. Inspect all studs for stripped or damaged threads, bent or loose condition, and signs of stretching. f. GEARS. Inspect...
Inspection
Check recoil damper rod spring (1) for free length of 1-3 4 in. 11 32 in. (44.5 mm 8.7 mm). If length is incorrect, replace recoil damper rod spring. b. Check reservoir piston helical spring (2) for free length of 6-13 32 in. 1-9 32 in. (162.7 mm 32.5 mm). If length is incorrect, replace helical spring. c. Visually inspect damper housing plug (3), damper housing cap (4), recoil damper rod (5), damper spring valve (6), helical spring (7), damper sleeve spacer (8), reservoir piston helical...
Installation Continued
Insert headed straight pin (9) through holes in recoil housing cap (7) and recoil damper rod (8). a. Insert new cotter pin (10) through hole in headed straight pin (9). b. Bend cotter pin (10) ends in opposite directions around headed straight pin (9). a. Finger-tighten damper nut (6) so that it contacts breech tab (11). b. Torque damper nut (6) to 108 ft-lb 8 ft-lb (146.45 N-m 10.85 N-m).
Note
Make sure rear gate assembly is between rim guide and pivot before installing capscrew. d. Insert capscrew (9) through rear gate assembly (8). e. Turn rear plate assembly (2) around. f. Install flat washer (10) and new self-locking nut (11) on threaded end of capscrew (9). 4. INSTALL REAR PLATE ASSEMBLY (WP 0073 00). 5. PERFORM FEEDER DRIVE ASSEMBLY MANUAL CYCLE AND ELECTRICAL CHECK (WP 0018 00). 6. INSTALL UPPER EJECT GUIDE (WP 0042 00). 7. INSTALL STEPPED SPACERS (WP 0041 00). 8. INSTALL...
Warning
If M919 usage is suspected, prior to performing any M242 weapon maintenance procedures, survey the muzzle end of the gun barrel with an AN VDR-2, PDR-27 or equivalent radiation detection instrument, in accordance with its prescribed operating procedures (see TM 11-6665-251-10 or TM 11-6665-361-10). If the barrel is found to be radioactively contaminated, the barrel is to be taken out of service without being cleaned, ends sealed with tape, and the barrel marked Low Level Radioactive Waste....
Warning Summary
Obey all safety rules, regulations, and orders when handling or working with guns. Do not touch electrical conductors. Serious injury or death may occur if extreme care is not used. Never remove barrel assembly with live ammo in the gun. Gun barrels get very hot and stay hot for a long time after firing. Touching hot gun barrels and parts will cause serious flesh burns. Heat mittens must be worn to prevent burns. Gun assemblies are heavy. Gun receiver weighs approximately 41.7 kg (92 lb). Gun...
Yes
Remove and inspect recoil mechanism (WP 0049 00). If not damaged or leaking, service recoil mechanism (WP 0049 00). If damage or leakage exists, replace recoil mechanism (WP 0049 00) and send defective recoil mechanism to Direct Support Maintenance for repair. FULL ROD PROTRUSION INDICATES MAX FULL FLUID RESERVOIR (AT +77 F (+25 C)
Warning Summary Continued
If M919 usage is suspected, prior to performing any M242 weapon maintenance procedures, survey the muzzle end of the gun barrel with an AN VDR-2, PDR-27 or equivalent radiation detection instrument, in accordance with its prescribed operating procedures (See TM 11-6665251-10 or TM 11-6665-361-10). If the barrel is found to be radioactively contaminated, the barrel is to be taken out of service without being cleaned, ends sealed with tape, and the barrel marked Low Level Radioactive Waste....
Maintenance Functions Continued
To adjust specified variable elements of an item to bring about optimum or desired performance. 6. Calibrate. To determine and cause corrections to be made or to be adjusted on instruments of test, measuring, and diagnostic equipment used in precision measurement. Consists of comparisons of two instruments, one of which is a certified standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instrument being compared. 7. Remove Install. To remove and install...
No
Remove bolt and track assembly (WP 0053 00). Remove bolt and carrier assembly from track assembly (WP 0054 00). Check carrier for galls and bends. Do these conditions exist Replace upper eject guide (WP 0042 00)._ Check link shield for bends and cracks. Do these conditions exist Check ejection chute for cracks, bends, deep dents, and breaks. Do these conditions exist Replace ejection chute (WP GG32 GG)._ Check breech bolt for galls, bends, and wear on breech bolt lugs and extractor lips. Do...
Explanation of Columns in the MAC
Column (1) lists functional group code numbers, the purpose of which is to identify maintenance significant components, assemblies, subassemblies, and modules with the Next Higher Assembly (NHA). Column (2) - Component Assembly. Column (2) contains the names of components, assemblies, subassemblies, and modules for which maintenance is authorized. Column (3) - Maintenance Function. Column (3) lists the functions to be performed on the item listed in Column (2). (For a...
Reporting Equipment Improvement Recommendations
If your gun needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tell us what you don't like about your equipment. Let us know what you don't like about the design. Put it on SF 368, Product Quality Deficiency Report. Army users mail it to us at Commander, US Army Armament Research, Development and Engineering Center, ATTN AMSTA-AR-QAW-C(R) Customer Feedback Center, Rock Island, IL 61299-7300. Marine Corps personnel will submit SF 368 in accordance with MCO...
Removal
PLACE AUTO GUN RECEIVER ON A CLEAN, FLAT SURFACE. a. Position auto gun receiver (1) with bolt and track assembly (2) on top. b. Verify that straight drive shaft (3) is in the lowered position. b. Verify that straight drive shaft (3) is in the lowered position. a. Push in sear release link (4) and rotate straight drive shaft (3) in fire direction. Release sear release link (4). b. Rotate straight drive shaft (3) until bolt and carrier assembly (5) moves forward and off the rear track (6) and...
Torquing
Where needed, torque values are listed in the maintenance task. The torque values given in the text of this manual are the actual values that must be applied to the nut or screw for proper maintenance. b. Some tasks require the use of a torque wrench adapter when the nut or screw cannot be reached with a regular socket on the end of the torque wrench. These adapters add to the overall length of the torque wrench and make the dial or scale reading less than the actual torque applied to the...
Explanation of Columns in the Tools and Test Equipment Requirements
Column (1) - Tool or Test Equipment Reference Code. The tool or test equipment reference code correlates with a code used in Column (5) of the MAC. Column (2) - Maintenance Level. The lowest category of maintenance authorized to use the tool or test equipment. Column (3) - Nomenclature. Name or identification of the tool or test equipment. Column (4) - National Stock Number (NSN). The NSN of the tool or test equipment. Column (5) - Tool Number. The manufacturer's part number, model number, or...
The Army Maintenance System MAC
This introduction provides a general explanation of all maintenance and repair functions authorized at various maintenance levels under the standard Army Maintenance System concept. The MAC (immediately following the introduction) designates overall authority and responsibility for the performance of maintenance functions on the identified end item or component. The application of the maintenance functions to the end item or component shall be consistent with the capacities and capabilities of...
25mm M242 National Stock Number
In addition to the Introduction work package, this RPSTL is divided into the following work packages. 1. Repair Parts List Work Packages. Work packages containing lists of spares and repair parts authorized by this RPSTL for use in the performance of maintenance. These work packages also include parts which must be removed for replacement of the authorized parts. Parts lists are composed of functional groups in ascending alphanumeric sequence, with the parts in each group listed in ascending...
Lists
Metric US Customary Measurement Chart. Measurements in this manual are given in both metric and US customary units. The table inside the back cover compares metric measurements to their equivalent US customary units. Also provided are conversion factors to convert metric units to US customary units. b. Nomenclature Cross-Reference List. Throughout this manual, most items are referred to by their official nomenclature. In the list, the items referred to by their common names are listed...
Lockwire
(1) Lockwire must be tight after installation to prevent failure due to rubbing or vibration. SAFETY WIRING ANGULAR DRILLED BOLT HEAD (2) Lockwire must always be installed so that it tends to tighten the part, thereby counteracting the natural tendency of the part to loosen. Determine whether the part tightens when turned to the right or to the left, as this governs the direction in which the lockwire is to be threaded through the safety hole. The illustrations above show typical methods for...
Corrosion Prevention And Control
Corrosion Prevention and Control (CPC) of Army material is a continuing concern. It is important that any corrosion problems with this item be reported so that the problem can be corrected and improvements can be made to prevent the problem in future items. While corrosion is typically associated with rusting of metals, it can also include deterioration of other materials such as rubber and plastic. Unusual cracking, softening, swelling, or breaking of these materials may be a corrosion...
Assembly Continued
Install cam-pin assembly (3) into breech bolt (1) so that top of cam-pin assembly (3) is flush with carrier assembly (2). 2. INSTALL FIRING PIN ASSEMBLY AND FIRING PIN SLEEVE. a. Slide rear of firing pin assembly (4) through front of firing pin sleeve (5). Pass firing pin tang (6) along groove in firing pin sleeve (5). b. Slide firing pin assembly (4) and firing pin sleeve (5) into rear of breech bolt (1).
Maintenance Functions
Maintenance functions are limited to and defined as follows 1. Inspect. To determine the serviceability of an item by comparing its physical, mechanical, and or electrical characteristics with established standards through examination (e.g., by sight, sound, or feel). This includes scheduled inspection and gagings and evaluation of cannon tubes. 2. Test. To verify serviceability by measuring the mechanical, pneumatic, hydraulic, or electrical characteristics of an item and comparing those...
End Of Work Package
M242 25-MM AUTOMATIC GUN (NSN 1005-01-086-1400) M242 25-MM ENHANCED AUTOMATIC GUN (NSN 1005-01-454-0396) The barrel assembly gives directional control to projectile. The barrel assembly consists of the following components. (1) Receives rounds in the cartridge chamber at breech end of barrel. (2) Helps contain explosive force when round fires. (3) Develops a right-spin rotation to projectile. (1) Counters some explosive recoil force.
Gun Fires Without Hangfire Protection Continued
Remove sear assembly (WP 0065 00) and check sear and sear sleeve-pivot for bends, breaks, and galls. Check cover assembly for broken spring and improper spring height (WP 0063 00) (Proper height is 27 64 in. + 1 16 in. (10.7 mm + 1.6 mm)). Do these conditions exist 0.42 IN.+ 0.06 IN. (10.7 MM+ 1.6 MM) Replace sear assembly (WP 0065 00), sear sleeve-pivot (WP 0065 00), or sear cover assembly (WP 0063 00), as applicable._ 0.42 IN.+ 0.06 IN. (10.7 MM+ 1.6 MM) Check chain for cracked or worn safety...
M242 25mm Firing Pin For Sale
INSPECT BOLT AND CARRIER ASSEMBLY PARTS. a. Visually inspect firing pin assembly (1) for broken spring. If spring is broken, replace firing pin assembly. b. Visually inspect firing pin assembly (1), breech bolt (2), firing pin sleeve keeper (3), firing pin sleeve (4), cam-pin assembly (5) and carrier assembly (6) for cracks and breaks. If either of these conditions are found, replace defective part. c. Check breech bolt (2) firing pin hole (7). If 0.125 in. drill bit shank fits into the firing...
Electrical Checkout Continued
Disconnect FSS harness J2 from index drive cover assembly (WP 0047 00). Check for a short circuit by checking continuity between pins P1-L & J2-D and P1-K & J2-B. Is there a short circuit (continuity) Replace feeder assembly (WP 0026 00) and send defective feeder assembly to Direct Support Maintenance for repair of index drive cover assembly._
Disassembly
Place damper housing assembly (1) on clean work surface. b. Press recoil damper rod (2) until second hole (3) in indicator rod (4) can be seen or insert lock pin (5) in first hole (6) and pull indicator rod (4) out. c. Insert a lock pin (5) in second hole (3) of indicator rod (4). Spring support threads may be damaged if clamped in a vise. Clamp vise jaw caps only on support flats. d. Place damper housing assembly (1) in vise with vise jaw caps with indicator rod (4) at bottom.
M242 Gun Electrical Cable
Slide yoke actuator may be attached to feed select solenoid when removed. If it is, reinstall slide yoke actuator. 3. REMOVE ELECTRICAL FEED SELECT SOLENOID. a. Place automatic gun feeder (1) against work surface with electrical feed select solenoid (5) positioned as shown. c. Lift electrical feed select solenoid (5) from automatic gun feeder (1). 1. INSPECT ELECTRICAL FEED SELECT SOLENOID WIRING HARNESS. Visually inspect electrical feed select solenoid wiring harness connector for loose,...
M242 Feed Stop Movement
The functional cycle check in upper feed will be identical to the functional cycle check in lower feed except for feed sprocket and feed shaft stop assembly movement. When in upper feed, the upper feed sprocket and upper feed shaft stop assembly will operate. 8. REPEAT FUNCTIONAL CYCLE CHECK WITH UPPER FEED SELECTED. Repeat functional cycle check, steps 3 through 6. Rotate hand crank (1) counterclockwise and pull out of hub (2). 10. INSTALL BARREL ASSEMBLY (WP 0023 00). END OF WORK PACKAGE M242...
M242 Upper And Lower Shouldered Shafts
All assemblies must be removed at the same time. To facilitate removal of shouldered shafts, pull up slightly on gear clutch assembly. a. Grasp shouldered shafts (13) and (14) and pull up and slightly to the side and remove shouldered shafts with lower and upper sliding sleeve clutches (17) and (18) and clutch yoke assembly (19). b. Slide lower and upper sliding sleeve clutches (17) and (18) and clutch yoke assembly (19) over the top of shouldered shafts (13) and (14). c. Remove lower and upper...
Lubrication
LUBRICATE BARREL SUPPORT ASSEMBLY. a. Using acid brush, fill grooves inside barrel support assembly (1) with grease. b. Using acid brush, apply a light coat of grease to flat surfaces inside barrel support assembly (1). a. Using acid brush, apply a light coat of general lubricating oil to barrel assembly (2). b. Using cleaning rod and cleaning swab, apply a light coat of oil to bore of barrel assembly (2).
M242 Index Drive Shaft
If index drive assembly is stuck on index drive shaft, tap lightly to loosen. d. Grasp index drive shaft (34). Remove index drive assembly (36) from index drive shaft. a. Remove three capscrews (38) from hub (39). b. Remove hub (39) and bevel gear (40) from feeder housing assembly (1). c. Remove bevel gear (40) from hub (39). a. Remove three capscrews (41) from access cover (42). b. Lift access cover (42) from feeder housing assembly (1). 24. REMOVE PAWL-SHAFT ASSEMBLY AND TIMER LEVER. a. Pull...
Pmcs Procedures Continued
Unit Preventive Maintenance Checks and Services for M242 Automatic Gun - Continued Table 1. Unit Preventive Maintenance Checks and Services for M242 Automatic Gun - Continued M Monthly SA Semi-annually AN Annually Perform Auto Gun Receiver Manual Cycle Check WP 0008 00. Remove Clean Inspect Service Lubricate Install recoil mechanism per WP 0049 00. Remove Inspect Lubricate Install per WP 0051 00. Remove Inspect Lubricate Install per WP 0051 00. Remove Disassemble Clean Inspect...
How To Check The Continuity Of
Remove the feeder assembly from receiver. Check for continuity through motor between pins J1-L & J2-P and J1-M & J2-K. Is there continuity _ Disconnect FSS harness J2 from index drive cover assembly (WP 0047 00). Check for continuity between pins P1-P & J2-C and P1-K & J2-D. Is there continuity _ Replace direct current motor (WP 0061 00). Replace feeder assembly (WP 0026 00) and send defective feeder assembly to Direct Support Maintenance for repair of index drive cover assembly._...
Drop In Auto Sear Dimensions Ar-556
Sear retractor pivot should only be removed if cracked or bent. d. Remove sear retractor pivot (5) from auto gun receiver (1). a. Visually inspect both sides of cover assembly for cracks, breaks, and bends. If any of these conditions are found, replace cover assembly. b. Check cover assembly for proper spring height. Height from tip of flat spring to cover should be 27 64 in. 1 16 in. (10.7 mm 1.6 mm). If measurement is not met, bend spring to proper height or replace cover assembly. a....
M242 Sear Catch Assembly
Straight headless pin can be removed only one way. a. Push straight headless pin (3) out of auto gun receiver (1). b. Lift sear catch assembly (2) out of auto gun receiver (1). Visually inspect sear catch assembly (1) for cracks, bends, breaks, and missing or loose plunger button (2). If any of these conditions are found, replace sear catch assembly. Using acid brush, apply a light coat of grease to outside of sear catch assembly (1) and straight headless pin (2). a. Place sear catch assembly...
M242 Recoil Mechanism 12524530
There are two types of recoil mechanisms used on the M242 Enhanced and Standard guns. The M242 Enhanced Gun can only use the 12524530 recoil mechanism. It can be identified by it's 16 outer ring springs. The M242 Standard Gun must use the 12524420 recoil mechanism. It can be identified by it's 17 outer ring springs. There are two different lengths of recoil housing caps. Part numbers 12524529 and 12524422, revision C or higher, have an overall length of 4.3 in. 109.1 mm . This length cap must...
Feeder Assembly
M242 Gun Electrical System Block Diagram. Figure 2. M242 Gun Electrical System Block Diagram. The electrical system consists of the direct current motor, electrical sear solenoid, electrical feed select solenoid, and index drive cable assembly. See Figures 3 and 4 for the electrical wiring diagrams. Component functions are a. DIRECT CURRENT MOTOR Operates on voltages between 18 and 30 Vdc and drives the auto gun receiver and automatic gun feeder gears. Contains junction and connectors...
Army
Upon receipt of equipment, unpack the contents and perform the following checks 1 Inspect the equipment for damage incurred during shipment. If the equipment has been damaged, report the damage on SF 364, Report of Discrepancy Packaging . 2 Check the equipment against the packing slip to see if the shipment is complete. Report all discrepancies in accordance with the instruction of AR 735-11-2. b. RECOIL MECHANISM. Verify that the recoil damper rod position and fluid level are correct. Place...
How To Assemble Modesto Santos .25mm
REMOVE LOWER RIGHT STEPPED SPACER. Loosen capscrew 3 . Remove capscrew 3 and lower right stepped spacer 4 from feeder drive assembly 1 . 3. POSITION FEEDER DRIVE ASSEMBLY. Position feeder drive assembly 1 with lower feed sprocket assembly 5 at top. 4. REMOVE LOWER CENTER STEPPED SPACER. Loosen capscrew 6 . Remove capscrew 6 and lower center stepped spacer 7 from feeder drive assembly 1 .
How To Use This Manual Continued Troubleshooting Overview
This procedure is designed to isolate failures in the gun system. The procedure should start with a step-by-step functional test in the Operator's Manual to identify the problem. The functional test sends the mechanic to troubleshooting procedures, isolating the malfunction. When the malfunction is located, the mechanic is sent to the replace or repair work package. After the repair is finished, the mechanic is sent back to the functional test. This verifies a successful repair. After a...
Reporting Errors And Recommending Improvements
You can help improve this publication. If you find any mistakes or if you know of a way to improve the procedures, please let us know. Submit your DA Form 2028 Recommended Changes to Publications and Blank Forms , through the Internet, on the Army Electronic Product Support AEPS website. The Internet address is http aeps.ria.army.mil. If you need a password, scroll down and click on ACCESS REQUEST FORM. The DA Form 2028 is located in the ONLINE FORMS PROCESSING section of the AEPS. Fill out the...
M242 Automatic Parts
Wear eye protection when removing retaining ring. Personnel can be blinded if struck in the eye by retaining ring. a. Insert small end of straight drive shaft 1 in opening 2 in bottom of auto gun receiver 3 . b. Push button 4 in center of straight drive shaft handle 5 , and push straight drive shaft 1 in as far as it will go. Release button 4 . c. Pull on straight drive shaft handle 5 to make sure that straight drive shaft 1 is locked in place. d. Install new retaining ring 6 in groove 7 on...
Upper And Lower Feed Sprocket On The M242
Feeder drive assembly has been positioned with the lower feeder drive assembly hole and splines in the uppermost or top hole position. If feed sprocket assemblies are installed with round positioner spring attached, feed sprocket assemblies may need to be pulled against spring tension to align holes. 1. INSTALL UPPER FEED AND LOWER FEED SPROCKET ASSEMBLIES. a. Align lower feed sprocket assembly 1 short shaft with lower feeder drive assembly hole 2 top hole . b. Twist lower feed sprocket...
Assembly
ALIGN BOLT AND CARRIER ASSEMBLY WITH TRACK ASSEMBLY. a. Stand track assembly 1 on end with drive sprocket wheel 2 at upper left. b. Center slider 3 at rear of track assembly 1 . c. Align track path 4 of bolt and carrier assembly 5 with track rails and slider 3 of track assembly 1 . 2. INSTALL BOLT AND CARRIER ASSEMBLY ON TRACK ASSEMBLY. a. Lift master link 6 , and position slider 3 on top of two lugs located in slider path 7 of bolt and carrier assembly 5 . b. Rotate roller assembly chain 8...
M242 Rocker Assembly
Repair chain guide and mechanical interlock by replacing defective rocker assembly parts WP 0069 00 ._ Repair chain guides and mechanical interlock by cleaning and or replacing operating rod assembly WP 0069 00 ._ Install rear chain guide WP 0069 00 . Install sear assembly WP 0065 00 . Assemble bolt and track assembly WP 0054 00 . Install bolt and track assembly WP 0053 00 . Perform auto gun receiver manual cycle check WP 0008 00 .
25mm Straight Drive Shaft Item Number
Repair track assembly WP GG56 GG ._ Push outside edge of sear retractor assembly until it clicks into position. Rotate straight drive shaft in FIRE direction until bolt carrier moves through full rear position and continues forward to mid-ram position. Does the push rod extension remain in the down position _ Repair chain guides and mechanical interlock WP 0069 00 . AUTO GUN RECEIVER MANUAL CYCLE CHECK - Continued Strike rocker assembly with a non-steel rod in a straight downward motion. Does...
Steps Prior Installing Gear Clutch In The M242
Do not clean annular ball bearings in solvent or allow solvent to run into bearings. Solvent will remain in bearing and dissolve lubricant, resulting in excessive wear or damage to bearing. a. Using brush and dry cleaning solvent, clean spur clutch gearshaft 1 and shouldered clutch shaft 2 . b. Wipe annular ball bearing 3 with clean, dry wiping rag. a. Visually inspect spur clutch gearshaft 1 and shouldered clutch shaft 2 for cracks and broken shaft splines and gear teeth. If any of these...
Chain Gun Receiver
Inspect repair rear chain and mechanical interlock mechanism Inspect repair rear chain and mechanical interlock mechanism GUN FIRES INTERMITTENTLY OR AT IRREGULAR RATE - Continued M242 25-MM AUTOMATIC GUN NSN 1005-01-086-1400 M242 25-MM ENHANCED AUTOMATIC GUN NSN 1005-01-454-0396 GUN FIRES WITHOUT HANGFIRE PROTECTION TooIs and Special Tools Equipment Conditions Artillery and turret mechanic's tool kit item 41, WP 0023 00 Barrel assembly removed WP 0085 00 Turret mechanic's supplemental tool kit...
Feed Select Soilenoid 25mm
Slide yoke actuator may be attached to feed select solenoid when removed. If it is, reinstall slide yoke actuator. 5. REMOVE ELECTRICAL FEED SELECT SOLENOID. a. Place automatic gun feeder 1 against work surface with electrical feed select solenoid 15 positioned as shown. c. Lift electrical feed select solenoid 15 from automatic gun feeder 1 . 1. INSPECT ELECTRICAL FEED SELECT SOLENOID. a. Visually check electrical feed select solenoid 1 for cracks, bends, and broken parts. If any of these...
Feeder Drive Assembly Manual Cycle And Electrical Check Continued
Depress timer release rod and rotate hand crack approximately 1 4 turn in the FIRE direction to disengage pawl shaft from the index drive shaft. UPPER FEED AMMUNITION STOP PATH ASSEMBLY A total of nine hand crank or worm shaft revolutions are required to completely cycle the index drive shaft control cam from SEAR position, back to SEAR position. UPPER FEED AMMUNITION STOP PATH ASSEMBLY Continue rotating hand crank in the FIRE direction while observing the lower feed...
M242 25mm Barrel Extension
Press inside edge of sear retractor assembly to release sear retractor, and cycle receiver into MISFIRE. Press and release sear release link while turning straight drive shaft in FIRE direction until master link is locked in SEAR. Repair chain guides and mechanical interlock WP 0069 00 ._ If automatic gun feeder is not going to be installed, raise drive shaft to prevent damage. Auto gun receiver manual cycle check is complete and receiver is timed. AUTO GUN RECEIVER BOTTOM VIEW SEAR M242 25-MM...
Gun Auto 25mm M242
Cloth MIL-C-20696, Type 1, Class 3, NSN 8305-00-515-4244 Drawcord MIL-C-7515, Type 1, NSN 4020-00-113-3896 2. All dimensions are in inches. Manufacture Instructions for Index Drive Cover Shim 1. Make from 0.020 in. shim stock, MS22499 3-005, NSN 9515-00-003-6943. 2. All dimensions are in inches. Manufacture Instructions for Recoil Mechanism Damper Rod Tool Use with Recoil Housing Cap Part Number Use with Recoil Housing Cap with Overall Height of 12524422 Revision B or Lower 12524422 Revision C...
M242 Feeder Housing Assembly
Use helper to hold feeder housing assembly. a. Stand feeder housing assembly 1 on end with spur gears 11 and 12 on top. b. Pull two spur gears 11 and 12 from shouldered shafts 13 and 14 . 7. REMOVE YOKE ACTUATOR AND FORK SHAFT ASSEMBLY. a. Slide yoke actuator 15 out of feeder housing assembly 1 . b. Screw 5 mm capscrew into fork shaft assembly 16 . c. Pull fork shaft assembly 16 out of feeder housing assembly 1 .
Internal Splines Of The Lower And Upper Sliding Sleeve In The M242
Worm shaft gear and bevel gear are parts of a serialized, matched set. Both gears must be replaced if either part is defective. Index drive shaft and index drive assembly are parts of a serialized, matched set. Both parts must be replaced if either part is defective. 1. INSPECT WORM SHAFT ASSEMBLY COMPONENTS. a. Visually inspect worm shaft 1 and bevel gear 2 for wear, cracks, broken teeth, and stripped threads. If any of these conditions are found, replace defective part. b. Visually inspect...
Cleaning
All parts must be cleaned well and kept clean during maintenance. Dirt or foreign matter can cause malfunctions and equipment failure. Cleaning procedures are covered in the task relating to the specific part. When using adhesives, paint, or dry cleaning solvent, apron, gloves, and goggles should be worn, and a respirator should be used if not working in a well-ventilated area. b. AVOID ABRASIVES. Except where called for in a task, do not use abrasives, files, wire brushes, or sharp...
Electrical System Operation Continued
SHUNT POWER SHUNT RETURN ARMATURE AND FEED SOLENOID I RETURN J NORMAL SHUTDOWN SENSOR J SEARED 1 P2 is only used on PN 12524168 amp 12524404 Feed Select Solenoids. The Feed Select Solenoid Harness is hard wired on the PN 12524181 Feed Select Solenoid. Feed Select Solenoid P1 Pin N Jumper Wire is only installed on PN 12524403 Feed Select Solenoid Harness. Motor J1 Pin U Jumper Wire is only installed on PN 12524409 Direct Current Motor. Figure 3. Electrical Wiring Diagram for Standard M242 Gun....
Location And Description Of Major Components
BARREL ASSEMBLY Mounts in front end of auto gun receiver. The barrel gives directional control to the projectile and brakes some of the barrel recoil. The ribbed barrel has two types of internal finishes, nitride and chrome. While either type of barrel is usable on the standard gun, the chrome barrel is required for the enhanced gun. The non-ribbed barrel is only used on the standard gun. 1 Mounts on top of auto gun receiver. 2 Removes linked ammunition from chutes. 4 Places round into face...
M242 25mm Bushmaster Chain
Place feeder handle in down locked position to protect electrical connector on bottom of automatic gun feeder. 1. PLACE M242, 25-MM AUTOMATIC GUN ON A CLEAN, FLAT SURFACE. Position M242, 25-mm automatic gun 1 as shown. 2. LOCK M242, 25-MM AUTOMATIC GUN IN SEAR POSITION. a. Rotate straight drive shaft 2 counterclockwise until M242, 25-mm gun stops and becomes locked. b. Visually check bolt position indicator 3 to verify that M242, 25-mm automatic gun 1 is locked in SEAR position. c. If M242,...
Auto Gun Receiver Operation
AUTO GUN RECEIVER Rams and fires rounds. Extracts and ejects spent cases or unfired rounds. Contains a mechanical interlock system that stops the gun if a round misfires or hangfires. The auto gun receiver consists of the receiver gears, track assembly, and bolt and carrier assembly, and includes the following subassemblies 1 BARREL SUPPORT ASSEMBLY Holds breech assembly in auto gun receiver and supports barrel. 2 RECOIL MECHANISM Absorbs most of recoil force when round fires. The enhanced...
Control Cam Installation In The M242
Do not drop lockwire pieces into gun. Wire can get between moving parts and damage gun. a. Visually inspect automatic gun feeder 1 for cracked, bent, or broken parts. If any of these conditions exist, replace those defective parts. b. Visually inspect automatic gun feeder 1 for loose or missing hardware. Tighten or replace hardware as needed. c. Visually inspect link strippers 2 , cam bushing screw 3 , ejection chute 4 , cartridge guide 5 , worm shaft nut 6 , and wire harness 7 for installed...
Differences Between Standard And Enhanced M Guns
The Enhanced M242 gun M242 ENH can be identified by the following markings Receiver, PN 12524301 Stamped with M242 ENH on the receiver side. Feeder Assembly, PN 12524100-1 Has quick detachable bridges. Barrel Assembly, PN 12524520 Ribbed barrel assembly with chrome lined bore. b. M242 ENHANCED GUN UNIQUE COMPONENTS. While the Standard and Enhanced M242 guns share many common components, the Enhanced M242 uses a number of components that are unique and are...
PageWPChange
A - B i - WP 0001 00 - 0116 00 0 Index-1 - Index-14 0 Zero in this column indicates an original page ARMY No. 9-1005-200-23 amp P MARINE CORPS No. 08672A-23 amp P HEADQUARTERS DEPARTMENT OF THE ARMY U.S. MARINE CORPS WASHINGTON, DC, 11 June 2001 UNIT AND DIRECT SUPPORT MAINTENANCE MANUAL INCLUDING DEPOT MAINTENANCE REPAIR PARTS AND SPECIAL TOOLS LIST
Gun Enhanced Automatic Mm M Wequipment Eic Te
This manual supersedes TM 9-1005-200-20 amp P, dated May 1992, TM 9-1005-200-30 amp P, dated August 1992, TM 08672A-20 amp P 1, dated May 1992, and TM 08672A-30 amp P 2, dated August 1992, including all changes. DISTRIBUTION STATEMENT C. Distribution authorized to US Government agencies and their contractors. This publication is required for administration and operational purposes, as determined on 2 February 1987. Other requests for this document shall be referred to...
M242 Automatic P1
Camplate notch lags the bolt position indicator arrow by 90 degrees. Use hand crank to manually cycle feeder until bolt position indicator is 1 4 inch before COOKOFF ZONE cross-hatched area . While performing resistance check between pins P1-P amp P1-K on the FSS 14 pin connector, have helper look through bolt position indicator glass and hand crank feeder slowly until the actuator roller falls into the camplate notch. Did a reading of less than 0.5 ohms occur when roller fell into the camplate...
Differences Between Standard And Enhanced M Guns Continued
4 Barrel Assembly, PN 12524520 a Physical differences The M242 ENH guns have been fielded with a ribbed barrel assembly with a chrome lined bore to provide longer barrel life. Barrel assemblies fielded with Standard M242 guns round barrel assembly, PN 12524001 and ribbed nitride barrel assembly, PN 12524507 have nitride bores. b Interchangeability The ribbed chrome barrel assembly is useable on all configurations of M242 guns. The ribbed chrome barrel assembly components with the exception of...
25mm Wiring Harness
Do not overtighten screw or wiring harness will split. 3. CONNECT WIRING HARNESS CONNECTOR J2. a. Place automatic gun feeder 1 with feeder handle 12 on bottom. b. Connect wiring harness connector J2 13 to cable connector 14 . c. Install screw 15 on wiring harness connector J2 13 . Torque screw to 36 in.-oz 4 in.-oz 0.254 N-m 0.028 N-m . a. Position automatic gun feeder 1 with feeder handle 12 down and remove two capscrews 16 temporarily installed in index drive cover assembly 17 . b. Align...
Upper Eject Guide M242
Replace upper eject guide WP 0042 00 ._ Replace ejection chute WP GG32 GG ._ Repair bolt and carrier assembly by replacing carrier assembly WP 0055 00 ._ Repair bolt and carrier assembly by replacing breech bolt WP 0055 00 . Disassemble bolt and carrier assembly WP 0055 00 and check all parts for breaks, galls, and wear. Do these conditions exist Check breech assembly locking lugs for galls, burrs, and wear. Do these conditions exist
Info
Pry up on link shield 3 until it springs away from lower right stepped spacer 4 . b. Lift link shield 3 about 1 in. 25.4 mm . Push link shield 3 toward feeder drive assembly 5 until small curved portion of link shield 3 is clear of feeder standoff 6 and is under rear upper link stripper 7 . c. Lift and rotate link shield 3 to the right. Remove link shield 3 from feeder drive assembly 5 . Visually inspect link shield for bends and cracks. If either of these conditions are found, replace link...
Da Form 2408 Gun Automatic
Dry cycle and use of dummy rounds are not counted on the breech or firing pin. a. Use DA Form 2408-4 to determine how many rounds have been fired. Stamp the breech with an X for every 5,000 rounds fired. Use example below 0--- 4,999 rds no stamp 5,000--- 9,999 rds 1 stamps 10,000---14,999 rds 2 stamps 15,000---19,999 rds 3 stamps 20,000---24,999 rds 4 stamps Replace breech assembly at 25,000 rounds. b. Stamp appropriate number of Xs on the face of the breech assembly 6 . c. Using a fine stone,...
Automatic Gun Feeder Operation
AUTOMATIC GUN FEEDER FORWARD FEED SECTION The forward feed section pulls linked rounds into the gun separates the rounds and links places rounds in the bolt face removes spent round cases from the bolt face and aids in ejecting spent cases from the gun. The forward feed section consists of the following components a Supports upper feed and lower feed sprocket assemblies. b Supports feeder assembly rotor. c Provides mounting for the forward feeder gate, lower round guide, and the two forward...
Receiver Feeder Image
Perform auto gun receiver manual cycle check WP 0008 00 . Install mechanical interlock and rear chain guide WP 0069 00 . Assemble track assembly WP 0056 00 . Assemble bolt and carrier assembly WP 0055 00 . Assemble bolt and track assembly WP 0054 00 . Install bolt and track assembly WP 0053 00 ._ Repair chain guide s and mechanical interlock by replacing defective parts WP 0069 00 . M242 25-MM AUTOMATIC GUN NSN 1005-01-086-1400 M242 25-MM ENHANCED AUTOMATIC GUN NSN 1005-01-454-0396 Artillery...
Maintenance Procedures
Initial Setup is a list of everything needed in order to do maintenance on one part of the weapon. Tools and Special Tools Lists tools needed to perform maintenance. Materials Parts Lists expendable durable materials and 100 replaceable parts. Each material or part is followed by a part number or work package reference. If more than one part is needed, the quantity needed precedes the part number or reference. Personnel Required Lists the number of personnel needed when more...
Automatic Gun Feeder Operation Continued
FEEDER DRIVE ASSEMBLY Mounts and drives the forward feeder section components and controls feed selection. Provides a means to manually operate the gun during a power failure, and sends electrical signals to the turret controls indicating the position of the bolt. The feeder drive assembly contains the following components 1 WORMSHAFT ASSEMBLY Driven by the auto gun receiver drive shaft. The wormshaft assembly turns the worm wheel gear and also provides a means to manually operate the gun...
M242 Enhanced Feeder
M242 25-MM AUTOMATIC GUN NSN 1005-01-086-1400 M242 25-MM ENHANCED AUTOMATIC GUN NSN 1005-01-454-0396 EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES a. EXTERNALLY POWERED EP An electric motor, located on the bottom and to the rear of the auto gun receiver, drives all the moving parts inside the gun. Ammunition feeding, loading and firing, extraction, and ejection are all done by the motor. The gun does not depend on barrel recoil or expanding gases for operation. The auto gun receiver is...
Marine Corps Forms And Manuals
Technical manuals and miscellaneous publications Physical Security of Areas, Ammunition and Explosives Reporting of Item and Packaging Discrepancies The Army Maintenance Management System TAMMS Recommended Changes to Publications and Blank Forms Recommended Changes to Equipment Technical Publications Equipment Inspection and Maintenance Worksheet Explosives and Demolitions First Aid for Soldiers Marine Corps Warehousing Manual Quality Deficiency Report
Marine Corps Forms And Manuals Continued
Transportation and Travel Record of Transportation Discrepancies Recommended Changes to Publications and Blank Forms Technical Manual-Organizational Maintenance Manual Including Repair Parts and Special Tools List for Gun, Automatic 25-mm, M242 and Gun, Enhanced Automatic 25mm, M242 Technical Manual-Direct Support Maintenance Manual Including Repair Parts and Special Tools List for Gun, Automatic 25-mm, M242 W Equipment 1005-01-086-1400 and Gun, Enhanced Automatic 25-mm, M242 W Equipment...
M242 25mm Machine
Repair bolt and carrier assembly by replacing defective parts WP 0055 00 ._ Replace breech assembly WP GG5i GG ._ Assemble bolt and carrier assembly WP 0055 00 . Assemble bolt and track assembly WP 0054 00 . Install bolt and track assembly WP 0053 00 . Install barrel assembly WP 0023 00 . Place a dummy round in face of breech bolt and perform auto gun receiver manual cycle check WP 0008 00 . Perform automatic gun feeder manual cycle check WP 0007 00 ._ M242 25-MM AUTOMATIC GUN NSN...
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For enhanced guns only, verify that feeder handle is locked and check for continuity between pins T amp M on motor turret plug. Is there continuity Enhanced gun electrical checkout complete. Remove feeder assembly from receiver. Check for continuity through motor between pins J1-M amp J2-K and J1-T amp J2-N. Is there continuity Replace direct current motor WP 0061 00 . M242 25-MM AUTOMATIC GUN NSN 1005-01-086-1400 M242 25-MM ENHANCED AUTOMATIC GUN NSN 1005-01-454-0396 AUTOMATIC GUN FEEDER...
