Mk-19 Spiral Barrel Groove

long spiral. Each spiral will only cut grooves of one twist, so that in rifling barrels of different twists, different guide shafts must be used, each with its own twist of spiral groove.

The engine lathe of the screw-cutting type can be used to rifle barrels and the setup is not expensive. Some makers of engine lathes supply spiral attachments for their lathes. These have a set of gears with them and these gears, in connection with the gears regularly supplied with the lathe, will cut almost any required spiral. If the lathe has a large hollow spindle, the barrel can be passed through the spindle and held with the regular barrel chucks mounted on each end of the spindle. The oil tube which is attached to the rifling head can be held in a clamp fixture mounted upon the tool rest of the lathe. This is the most satisfactory method and requires the least fixtures. If however, the spindle is too small to allow the barrel to pass through it, the rifling head may be driven by the lathe spindle and the barrel can be held in a clamp fixture mounted upon the tool rest. In this case the clamp fixture holding the barrel should be fairly long and heavy, so that it may grip the barrel at two rather widely separated points. This method requires a longer lathe bed than the first method, as the bed must be long enough to accommodate the barrel length plus sufficient length for the rifling head with yet enough length of tube or pull rod on the rifling head so that it can pass clear through the barrel.

The lower priced lathes are not supplied with spiral attachments by their manufacturers but the higher grade lathes can be so supplied. These spiral attachments usually include an indexing attachment but if it does not, a simple one may be devised so that the rifling cutter is started in the barrel with the spindle in the correct position each time. An accurate protractor mounted on the spindle nose will do the trick.

Ordinary screw cutting lathe fitted up to rifle barrels. Worm gear is shown on lathe spindle behind barrel chuck. This gear is driven by worm on cross shaft beneath it and through bevel gears and spur gear meshed with spur gear on quick change gear box of lathe. Power, either by hand or motor, is applied at rear end of lead screw.

A spiral attachment may be built for a screw cutting engine lathe of the quick-change gear-type without much expense, outside of the labor involved, so that barrels may be rifled upon the lathe, driving it either by power or by hand.

To make this spiral attachment, obtain a stock worm gear and worm, the gear being large enough so that it may be bored out to slip over the lathe spindle nose with a close fit. This gear is held in place with a barrel chuck screwed tightly up against it. A bracket is now made to fit the lathe bed, just as the tail stock or center rest does, and on the upper part of this bracket, which can be clamped to the lathe bed with the clamp plate used with the center rest, a shaft is mounted, at right-angles to the center line of the lathe, and on this shaft the worm that mates the worm gear on the spindle nose is mounted so that it meshes with the worm gear. This worm shaft is long enough so that it extends to the front of the lathe, a little past the headstock. On this outer end of the shaft, a standard miter or bevel gear is mounted and a second miter or bevel gear meshes with this and is on a shaft extending to the head end of the lathe. A bracket for this shaft may be bolted to the side of the head-stock. At the head or gear end of the lathe, a gear is mounted on this shaft so that it meshes with the gear train leading from the lathe spindle to the quick-change gear box. This gear may have to be a special gear, if the gears on your lathe do not happen to be standard gears which can be purchased from some standard gear works. It may even be necessary to use two gears at this point to reach the lathe gear train. The ratio of these gears, and of the worm and worm gear, must be figured out for your particular lathe to bring the spiral produced within reach of the gear box gears of the lathe, so that all the common twists in rifling may be reached by simply shifting the gears.

In use, the belt pulleys of the lathe are disconnected from the spindle so that the spindle turns freely and the drive is applied at the tail end of the lead screw of the lathe. A hand crank may be applied to the end of the lead screw and after the half-nuts of the lathe carriage are closed upon the lead screw, the carriage is moved as the lead screw is turned; the lead screw in turning operates the gears at the head of the lathe and through the special shafts added, turns the spindle with the worm and worm gear. If desired, a pulley may be placed upon the end of the lead screw and a motor can be used to drive the lead screw. Vee-pulleys and vee-belt will make the best drive at this point. The gears necessary for this setup should not cost more than twelve or fifteen dollars, unless special gears have to be made for use at the head of the lathe. If the lathe is a small type, the cost for gears will not run more than half the above amount. Standard gears can be obtained from Boston Gear Works or from Chicago Gear Works or any other company producing what is known as standardized gears.

A goud grade of cutting oil must always be supplied under pressure to the barrel being rifled, to lengthen the life of the rifling cutter, to make a smoother cut and to keep the barrel clean of chips.

Forms of rifling of widely divergent types have been experimented with in years past, but rifling has finally settled down to two main forms, one in which lands and grooves are of equal width and the second in which the grooves are wide and the lands are narrow. These two types seem to give equally good results, although the groove and land of equal width are usually preferred for the jacketed bullet. Grooves in barrels to use lead bullets are often deeper than those in barrels for jacketed bullets, with the exception of the .22 caliber, although all manufacturers do not follow this practice.

Grooves should not be deeper than is necessary to grip the bullet well, as extremely deep grooves lead to rapid throat erosion and sometimes to fins upon the base of bullets which act as rudders and give the bullet an erratic flight. It is a good plan to follow the practices of some of our best rifle manufacturers, but this

Various types of rifling. A Charles Newton's segmental type, 5 grooves. B Newton's parabolic type, 5 grooves. C Harry Pope's 8 groove rifling. D standard type 4 groove. E standard type 5 groove. F standard type

6 groove rifling.

does not mean that it is useless to experiment, for who knows what you may develop.

In the work of relining barrels, the original barrel is bored out by a drill with a pilot to fit the original bore as previously described, the drill being started at the chamber end of the old barrel so that it will be well centered. The barrel is then reamed with a barrel reamer to bring it to the size of the tube to be inserted in it. These tubes come in two sizes, J4" and ¡Hi" and are already rifled, although some barrel reliners prefer to insert an unrifled tube in the old barrel and rifle it after it is in place.

Split brass bushings, tapered on the outside, are

Three Groove Barrel Pics

supplied with the relining tubes. These slip over the outside of the tube at each end and the ends of the old barrel must be reamed out with a reamer of the same taper as these bushings. These reamers have a pilot which fits the reamed barrel and thus the bushings center the liner in the barrel.

Three groove drill o£ high speed steel, with straight grooves, to bore out old barrels for relining.

The barrel to be relined is placed on a soldering stand, while gas jets play upon it, along its full length, from each side. When it reaches the proper heat it is tinned all over, inside, with a stiff wire brush or with a special copper tool supplied with grooves to hold the solder. If the brush is used, it is dipped into and saturated with regular tinners solder and the barrel is tinned by running the tool or brush through the barrel.

Standard commcrcial three groove twist drill, with pilot ground on it, to drill out old barrels for relining.

The liner has its ends plugged with wood plugs and is tinned on the outside. It is inserted in the barrel and worked back and forth so that excess solder is worked out and surfaces of both barrel and liner are evenly tinned. The liner is left about three inches longer than the barrel, an even amount being allowed to extend from each end of the barrel.

The split brass bushings arc tinned all over, then placed around the tube and tapped into the taper reamed for them at each end of the barrel.

Set the barrel upright while cooling. After it is cold, hang it up with a wire and strike it with a small hammer. If the job is well soldered, it will ring. If it does not ring, the liner will have to be removed and the soldering operation repeated until it does ring, showing a good tight job.

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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  • Caoimhe Donaldson
    Can mk 19 barrel be removed?
    3 years ago
  • ferdinanda
    Is the Mk19 barrel rifled?
    10 months ago

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