D Homemade Reamer

I would strongly recommend the use of a professionally ground reamer to cut the chamber of any barrel. However, if it is necessary to build your own reamer, the following method can be used. Unlike the chamber we cut in volume one, using a taper pin reamer, the straight walled case of the .32 and .380 cartridges means that an improvised chamber can be cut using a series of three drill bits. For the .32 chamber we require one, 7.8mm drill and two, 8.5mm, and, for the .380, a 9mm drill and two 9.5mm in diameter. Whichever of the two calibres it may be necessary to cut a chamber for, the only difference is the diameter of the drills used, all other measurements remain the same. We will proceed as if cutting the chamber for the .32 cartridge. First, three 78mm, or thereabouts, lengths of 14.29mm barrel tube are required, (See Figure 'OO) We will call these the 'Reamer Tubes' from now on. The inside diameter (ID) of each of the three tubes must first be reamed out using the three drill sizes given above, i.e. one tube is reamed out to a diameter of 7.8mm, and the remaining two tubes to a diameter of 8.5mm. As can be seen in the accompanying drawing, reamer tube No1 accepts the 7.8mm drill and the No2 and No3 tubes the 8.5mm drills. For the .380 chamber the No1 tube accepts the 9mm drill and the No2 and No3 tubes the 9.5

mm drills. After reaming out the tubes, a hole must be drilled to accept a socket screw in the position shown in the accompanying drawing. The purpose of the socket screw is to hold the drills firmly in position. Only one drill, the 8.5mm (9.5mm for the .380), requires any alteration before the 'reamer set' can be used to cut the chamber. The point of this drill must be removed, and in so doing, create a flat ended cutting tool. This can be achieved quite easily by touching the end of the drill point against the spinning wheel of a bench grinder, while at the same time, slowly rotating the drill so the point is evenly removed. It is worth pointing out that if a drill press is available to you, the point of the drill can be accurately removed by simply putting the drill in the drill chuck and lowering the spinning drill onto a grit (Carborundum) stone, however, most of the drill point will still need removing first, using the bench grinder, before using the drill press method of finishing the end of the drill.

The two cutting edges of the flat ended drill must now be re-sharpened by carefully 'touching' the back edges of the two cutters against the wheel of a bench grinder. This procedure is similar to re-sharpening the point of a drill, except for our purposes, the end of the drill is now a

FIGURE 'OO' REAMER CONSTRUCTION.

Homemade Machine Pistol

flat ended cutting tool. Place each drill in it's respective reamer tube and adjust the Nol drill until it protrudes 16mm from the end of the reamer tube,(excluding the drill point). Now adjust the No2 and No3 drills to 13mm and 14mm respectively. The drill measurement is the same for both the .32 and .380 calibres. When each drill is adjusted to the measurements given above, tighten each socket screw to prevent the drills from moving during use. A flat side must now be ground onto the side of each drill shank so they can be turned using a standard 'tap wrench/Holder'. Before the reamer set can be used a guide tube is required to ensure the chamber is accurately cut. This is nothing more elaborate than a 6 to" to 7" length of 20.64 x 2.95 mm tubing.

Our improvised reamer set is now ready for use. To cut the chamber proceed as follows. Firmly clamp the barrel tube in a vice at roughly a 45 degree angle to the vice jaws and slide the guide tube over the end of the barrel. Now slide the No 1 reamer drill into the guide tube as shown in the accompanying Photos, 45 and 46.

Each reamer drill is used in the order it is numbered, i.e. one, two and three. Apply a small amount of cutting compound, if available, to the tip of each reamer and proceed to cut the chamber. Slowly turn each reamer while at the same time applying a small amount of forward pressure until each reamer has cut fully to it's respective depth. At intervals during the cutting operation, clean out any metal shavings from the inside of the chamber.

After using the last (No3) reamer, place the No1 reamer back in the barrel tube and rotate it several times. This will be necessary to remove any burring present in the bottom of the chamber, caused by the use of the flat ended No3 reamer tool. Finally, using a wire barrel cleaning brush, remove any metal shavings etc, from inside the barrel and chamber.

The chamber is now cut and it should be possible to slide a cartridge into the chamber. The cartridge must slide in freely and under its own momentum before coming to a stop. At this point the base of the cartridge should protrude 3mm from the barrels breech, as we saw earlier in Chapter Seven.

After checking the cartridge fit and cutting the chamber mouth bevel, we can proceed to re-assemble the barrel.

The improvised chamber reamer is not the ideal method of cutting the chamber of a firearm, but it will suffice if a professionally ground chamber reamer is, for any reason, unavailable. It is worth pointing out, however, that the genuine article is so widely available, that it is well worth investing in one. They are relatively inexpensive and make the chambering of any gun barrel a quick and easy operation.

Gun Drill Reamers Chart

Photo's 45 and 46: The three piece reamer tool; and above, fitted to the barrel ready to cut the chamber.

Homemade Machine Pistol
Note the flat ended No3 reamer tool; shown third from left.
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Responses

  • Goldilocks
    What is the length of a .380 chamber reamer?
    4 years ago
  • heikki
    How to sharpen a drill bit on a bench grinder?
    3 years ago
  • nora
    How I make chamber reamers?
    3 years ago
  • asmeret
    How reamer a gun barrel?
    3 years ago
  • kiros
    How to make a 9mm dtype reamer for chamber?
    3 years ago
  • Aleksander
    How to make an improvised pistol barrel?
    2 years ago
  • marigold puddifoot
    What drill size is used for 9mm barrels?
    2 years ago
  • spartaco moretti
    How machine a chamber reamer?
    2 years ago
  • justin kerwin
    How to build a chamber reamer?
    2 years ago
  • rita
    How to make a 9mm chambering reamer?
    1 year ago
  • Ute
    What are the id measurements of barrel and chamber of 9mm?
    1 year ago

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