Chapter Five Barrel

In today's market, there are at least ten barrel manufacturers who can supply .35 caliber barrel blanks. These blanks are available in many configurations, ranging from feather-weight blanks to Bull barrels of up to one and three-eighths inch diameter for entire lengths of thirty inches or more. Since our project requires an eight inch section with a five-eighths inch diameter, it would seem to make sense to acquire a barrel blank slightly over twenty-four inches long. (Unthreaded and unchambered blanks are usually somewhat over twenty-four inches long.) This length, with a minimum diameter of five-eighths inch, will give you enough material to make three barrels.

At the present time there are several companies that manufacture and sell chamber reamers. These range in price from a low of around ten dollars to a high of thirty dollars. For our purposes, a finish reamer will suffice.

Specify that it will be used in a rifle barrel when you order it. If you don't, the company many send you a reamer with a pilot too big to enter the bore. This may happen because many pistol caliber reamers are made with the pilot ground to groove diameter or slightly larger for use in revolver cylinders. (I realize the nine millimeter'cartridge is used in automatic and semi-automatics, but there are revolver cylinders chambered for it on occasion. To avoid a foul-up, go ahead and specify that the reamer will be used for a rifle barrel.)

Incidentally, the higher priced reamers will usually have an integral throat reamer included, allowing you to work the entire chambering operation with a single reamer.1 The cheaper ones often require the additional use of a separate reamer for the throat portion. In most cases the higher priced reamer, such as those made by Clymer Manufacturing Company, will prove to be the cheapest in the long run. The barrel proper is rather simple to construct. Cut a section of the barrel blank to the proper length and square the ends in the lathe. After turning it to a diameter of five-eighths inch, thread one end eighteen threads per inch by one and one-half inches long. This will enable the barrel to screw into the receiver with the end flush against the inside face of the barrel bushing, leaving enough extra threads to accept a five-eighths inch by eighteen lock nut.

The muzzle end should be crowned with a lathe tool ground for this purpose, and finished,with a file and emery cloth. Follow this by finishing with 400 grit wet or dry sandpaper.

Feed the chamber reamer into the breech end of the barrel, with the barrel chucked. By turning at the slowest back gear speed pressure from the rail stock ram will push the reamer into the bore. Do not hold the reamer in a rigid tail stock chuck. It should be kept from turning with a hand-held tap wrench, a clamp, a small wrench, or some similar arrangement which will release and turn with the barrel if the reamer should suddenly decide to seize. The reamer should be well lubricated and removed and cleaned frequently. Another method of operation is to secure the barrel in a vise and turn the reamer in by hand using a proper tap wrench or reamer drive. If this method is used, care must be taken to feed the reamer straight, with no side pressure exerted in any direction.

An ideal chamber will result in this particular gun if you cut to a depth that will leave about a .010 inch gap between the breech block and barrel, when the breech block is in the closed (fired) position. Therefore, you should try cartridges (or a headspace gauge) in the chamber frequently as you approach the finish depth. When the cartridge head protrusion from the chamber equals the depth of the breech block counterbore (supposedly one-tenth inch), plus fifteen or twenty thousandths, you should screw the barrel in place in the gun. Tighten the lock nut, and after removing the firing pin, push the breech block forward as hard as you can. (It will be better to wait until the main spring is in place, allowing the spring to shove the bolt closed.) . The chamber will be of a satisfactory depth when a feeler gauge of .010 inch to .012 inch passes without resistance between the breech block and the barrel. A cartridge should be in the chamber when you make the feeler gauge test, of course, and the extractor and firing pin should be removed from the breech block. You should also make absolutely sure that your chamber is

THREAD * 16

THREAD * 16

8"

BARREL

BREE*H END SHOWING CHAMBEB DlKENSI√ľNo.

I/I6" RADIUS

Bill Holmes gathered the practical know-how contained within this book over a period of twenty years as owner, operator or gunsmith in several gun shops in several states.

Bill Holmes' home workshop submachine gun is short, comparatively light ar>£ easy lo handle

Sections of military ritle barrels, such as those pictured, may be reamed to size and rifled if no commercial blanks are available

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