Loading For Automatic Arms

When loading ammunition for hand operated rifles, single shot pistols or revolvers, the prime limiting factor is the chamber pressure. If the cartridges for any of these arms do not develop pressures in excess of those dictated by experience and good judgment and the ammunition is accurate, it can be considered as perfecdy satisfactory.

This is not always true of ammunition intended for use in the so-called "automatic" or self-loading arms for, although the pressures must be kept within safe limits, there are other factors which inject themselves into the situation. Automatic rifles and pistols depend for their functioning upon the use of a certain amount of the energy of the cartridge fired in them. As this energy is exerted to the rear, it is necessary to pay particular attention to it when loading the ammunition. In the hand operated arms, we think only of the effects produced upon the bullet and the movement of the bullet in a forward direction, but the peculiarities of the automatics make it necessary to 'think in two directions."

It is possible to reload ammunition with cast bullets that will cause severe battering of the moving parts of an automatic arm, even though the pressures developed are well within the recommended limits for the arm. The points to be observed in loading ammunition for the automatics depend upon the mechanical principle of operation 323 of the particular type of automatic arm that the ammunition is being loaded for. All self-loading arms do not work on the same principle and to understand the points to guard against in loading ammunition for any of them, it is first necessary to know in a general way how these arms operate. They are all the same in that firing a cartridge causes the breech to open, the cartridge case to be extracted and ejected, the arm cocked, a new cartridge to be pushed into the chamber and the arm left ready to be fired again by another pressure of the trigger—but the method by which these several things are accomplished differs.

The three general classifications of automatic or self-loading arms as they should more properly be called, are: blow-back, recoil operated, and gas operated. A fourth classification might well be placed between the first two and called "delayed blow-back/'

Blow-Back Actions. Blow-back actions are those in which the barrel and breech block are never locked together, the breech block remaining in the dosed position only by virtue of the tension of the rccoil spring. When a cartridge is fired in this type of action, the cartridge case is driven to the rear by the gas pressure at the same time that the bullet is driven forward. This two-direction thrust is, of course, common to all types of arms but in the blow-back action the head of the cartridge case docs not meet the resisting wall of a locked or solid breech— it pushes the movable breech block to the rear. Because of the weight and inertia of the breech block, to say nothing of the resistance of the recoil spring, friction and the effort to cock the piece, the rearward movement of the breech block is very much slower than the movement of the bullet Consequently, in this type of mechanism the brecch block only moves a small fraction of an inch to the rear and is not open far enough to permit the escape of gas by the time the bullet leaves the muzzle. The continued movement of the recoiling parts to the rear is due to the momentum given them during the short period of time the bullet is moving through the barrel. This momentum normally carries the breech block (or slide, in the case of an automatic pistol) to its rearmost position.

The thrust imparted to the breech block depends upon the same factors which govern the velocity of the bullet; namely, the chamber pressure and the manner in which the pressure is developed plus the area on which the pressure works, which can be translated into the area of the head of the cartridge case. For these reasons, the blow-back type of action is limited to the use of low power cartridges and, in the case of pistols, to cartridges of small head diameter. The rifles employing this principle ran use larger and more powerful cartridges because of the heavier breech blocks and stiffer springs that can be used in them, but even the rifle cartridges have decided limitations.

Blow-back actions are not adapted to the use of cartridges developing high velocities or high chamber pressures and in reloading ammunition for such arms the loads should never exceed the limits prescribed for standard charges.

All small frame automatic pistols that I know of, whether of domestic or foreign manufacture, up to .380 caliber (9 m/m short) operate on the blow-back principle. This is certainly true of the Colt automatic pistols in calibers .25, .32 and .380 as well as the .35 and .32 S. & W. automatics. Other pistols of this type in more or less common use in the United States arc the Ortgics and small models of Mauser automatics, to say nothing of the conglomeration of cheap mail order pistols.

Among rifles, we find only three American automatics operating on the blow-back principle. These are the Model '05 Winchester caliber .32 and .35 self-loading rifles, the Model '07 Winchester caliber .351 self-loading rifle and the Model 10 Winchester caliber 401 self-loading rifle. Being rifles, and allowing a greater amount of weight in the mechanism than in automatic pistols, more powerful cartridges can be used than in the blow-back pistol actions, but even so the cartridges for these automatic rifles are litde more than glorified pistol cartridges.

Any attempt to overload ammunition for any of the arms mentioned, even though the pressures are well below a dangerous point, can only result in injury to the arm. The velocity of the recoiling parts will be increased, this sooner or later will cause damage of one kind or another to the mechanism. The point to remember in reloading ammunition for these arms is that the normal chamber pressure is the limiting factor. Cast bullets, because of their soft nature, will start on their way and accelerate more quickly in a barrel than a jacketed bullet of equal weight and bearing surface. Consequendy, it is frequently possible in automatic, arms to get higher muzzle velocities with cast bullets than can be obtained with jacketed bullets and furthermore, this can be done without exceeding normal pressures.

Delayed Blow-Back. This is a cross between the blow-back and the recoil operated type of action. In it, the breech block is never really locked to the barrel but there is some mechanical resistance offered to the breech block to 324 delay its initial movement so it will not recoil and open as easily as a straight blow-back action. The only arms that the handloader is likely to encounter which operate on the delayed blow-back principle are the Savage automatic pistols. Practically, the "delay" in operation of these pistols is insignificant, if, indeed, there is any delay at all. Ammunition for them should be reloaded the same as for blow-back pistols of similar caliber.

Recoil Operated Arms. In the recoil operated type of automatic pistol or rifle we have a mechanism that is entirely different in principle from the blow-back and one which requires different treatment in loading the ammunition for it. In this type, the breech block and the barrel are securely locked together at the time the cartridge is fired and normally remain locked until the bullet is out of the 326 barrel. When the arm is fired the barrel and the breech, in a locked position, recoil to the rear together and the energy of recoil is used to unlock the breech from the barrel, permitting the breech block to continue its rearward movement alone, extracting the cartridge case from the chamber and performing its other normal functions. In this type of action the barrel and breech block can move to the rear independendy of the rest of the arm.

Among the automatic pistols operating on the recod principle, we find all the .38 caliber Colts as well as the .45 Government model, the Luger and the military Mausers. There is only one model of American auto rifle using center-fire ammunition in this category; namely, the Model 8 Remington autoloading rifle, which is made for the calibers .25, .30, .32 and .35 Remington cartridges.

As these recoil operated arms have their breech blocks or slides locked to the barrel it is possible to use more powerful cartridges in them than can be used in a blow-back arm, although even these locked actions have their limitations. During the interval that the two are locked together they recoil in much the same way chat a hand-operated rifle recoils when fired. The energy that is im-3*5 parted to them is influenced by the weight of the bullet, the barrel time and the rate that the bullet accelerates in the barrel. Lead bullets impress themselves into the rifling more easily than jacketed bullets and consequendy do not require as high a chamber pressure to develop a given velocity as a metal jacketed bullet. If lead bullets are loaded up to the limit of the permissible chamber pressure the acceleration of the bullet will be greater than a metal jacketed bullet and consequendy the velocity of the recoiling parts will be greater. This will lead to more or less upsetting and deformation of the parts of the gun that arrests the. rearward motion of the breech block. Many of the loads published in tables of charges do not take this factor into consideration, and it is a good plan for the re-loader who wishes to keep his self-loading rifle or pistol in 327 good condition to experiment with reduced charges and find out just how litde powder he can use with any given bullet to barelv cause the arm to function. With this mini-

mum as a base he can establish his charge somewhere between this point and any recommended load, but should never exceed any recommended full charge whether using lead or metal jacketed bullets. It is also a good plan with any automatic arm to examine the recoiling parts carefully from time to lime for any evidence of battering or upsetting, and the first sign of such a condition should be heeded and the load reduced slighdy.

The positive functioning of self-loading arms requires that the cartridges enter the chamber freely. Therefore the chambers arc apt to be a litde large. This condition may result in excessive expansion of the cases and tearing of the brass in the solid head of the case. This condition is described in detail under the subject of Resizing Cartridge Cases, but in order to be sure of proper functioning it is almost always necessary to resize the cases to their original dimensions. It depends upon the particular type of arm and the nature of the loads used. For example, the Luger, Mauser, .32 Auto and .380 Auto cartridge can sometimes be reloaded several times without resizing the cases. On the other hand, the 45 Auto and most of the automatic rifles are apt to malfunction if the cases are not resized full length every time they are reloaded. As previously mentioned, the resizing of cases that have cracks or tears in the solid heads is not desirable, but rarely causes any trouble when moderate loads are used except in the Cal. 45 Automatic Pistol. This caliber, while by no means dangerous to reload, is nevertheless worthy of special attention.

Reloading the .45 Automatic

This cartridge because of loose chambering and poor support at the lower part of the chamber where the metal is beveled to permit easy feeding of the cartridges from the magazine, bulges considerably at the head when fired. This causes cracks to occur in the solid head. The case is so large in diameter and so short that it is easy to inspect them for 328 this defect by merely looking into them in a good light, if they are cracked all the way around the inside of the head it is best to discard them.

The photograph shown on Plate XIX is of a section of a Cal. .45 Automatic Pistol barrel with a cartridge in the chamber. It will be seen that the cartridge is positioned in the chamber by the square, uncrimped edge coming in contact with the square shoulder of the chamber. This contact supports the cartridge against the blow of the firing pin. The head of the case is flush with the barrel extension. If the cartridge were crimped, it would go deeper into the chamber, the head space would be excessive, and a too light blow from the firing pin would cause ignition troubles.

It can be seen that the under side of the case receives very litde support and that the looseness of the chambering leaves a considerable space over the top of the cartridge. This is what causes the case to expand considerably and tear the brass apart slighdy inside of the solid head.

Unfortunately, all cases for the .45 auto are not as long as they should be and before reloading it is well to measure them. They should be from .892" to .898" long. A simple way to gauge them is to remove the barrel from the pistol and use it as a gauge. Resize the cases and try them in the chamber. The heads should be just flush with, or very slighdy below, the projection at the rear end of the harrel. If they project a few thousandths of an inch above this protection it will usually do no harm provided the slide can close and the disconnector ckn enter d\e depression in the under side of the slide. The thing to watch out for is short cases, and if you find any below the minimum dimension given above or any that seat appreciably below the end of the barrel it is best not to reload them.

One is limited in the variations that arc permissible cither in the weights or shapes of bullets that may be used in automatic pistols as well as in the dimensions of the finished cartridge. Sharp shoulder bullets will not feed 329 properly, but can be used if the pistol is used as a single shot weapon. The standard weight of bullet for the 45 Auto is 230 grains. If a lighter bullet is used, the gun will shoot lower than normal and a heavier bullet will make it shoot higher, regardless of the powder charge used« One is also limited as to the depth to which bullets may be seated. The diagram on this page has three dimensions marked A, B, and C. If the dimension A is moved back,

the length of the cartridge will be decreased. This will not usually effect the functioning, but it will increase the density of loading (decrease the air space), which will raise the pressure. If A is moved forward, the over-all length of the cartridge will be too great for it to enter the magazine.

If bullets longer than normal are used and the cartridge loaded to its proper length, the dimension B and the density of loading will be increased and as this would imply a heavier bullet than normal, the pressure and the recoil of the slide will be increased without any benefit in the external ballistics of the load.

The dimension C must be kept reasonably close to the normal for proper functioning.

A word about jamming. Jams are usually the fault of the magazine. If the lips become spread too much the head of the cartridge will jump out too quickly. If they are bent in too much they will not let the head come up quickly enough and the slide will ride over the head instead of pushing it into the chamber. In either case, the slide may 330 catch the cartridge in an abnormal position and cause a jam. This assumes that a bullet of the proper shape is used and that the projection of the bullet (dimension C on the sketch) is correct. The nose of the bullet should be rounded and more or less the same shape as the factory bullet.

Cast bullets for automatic arms may be any temper that one wishes to use but hard bullets resist deformation in handling and loading and in arms where the bullet rubs on the chamber wall while passing from the magazine into rhe chamber hard hidlets will have less "drag" than soft ones. This doesn't make any noticeable difference in functioning except when loads are reduced to an extent where they will barely function the mechanism.

Gas Operated Arms. This type of automatic is of little interest to the handloader for, in order to utilize the gasses of combustion to operate the mechanism the weight of the arm is usually increased to a point that renders it unsuitcd to sporting uses. With one exception, this principle is found only in military automatics or machine rifles and machine guns. The one exception is the Standard automatic rifle, now obsolete, which was chambcred for the Remington automatic rifle cartridges. This arm was not a bad one and was unique in that it could be functioned either as an automatic or as a hand operated, slide action rifle. There arc still quite a number of these Standard rifles in use and they arc much liked and sought after by those who arc familiar with them. If used as hand operated arms, the reloading of ammunition for them is subject to the same loading principles as that for any other manually operated rifle of the same caliber. As an automatic arm, little departure can be made from those loads which duplicate or approximately duplicate, the factory standard cartridge.

In gas operated arms there is a hole or port in the barrel at some distance back from the muzzle or some device at the muzzle that permits some of the gas behind the bullet to be utilized in operating the arm. As the bullet passes 331 the port, some of the gas escapes through the port and acts on a piston or other movable member, the motion of which unlocks the breech block or bolt and imparts the necessary movement to it. As these arms are designed for use with military or commercial ammunition developing relatively high pressures, they will not function with reduced loads or with quick burning powders. The pressure remaining behind die bullet must be high enough to function the arm when the bullet passes the point in the barrel where the gas escapes to act on the operating mcchanism.

Chapter Fifteen 33a

Was this article helpful?

0 0

Post a comment