Gas checks must be quite shallow and their function is limited to protecting the base of the bullet and preventing gasses from melting or getting past the base. If they are made deep, they become in effect bullet jackets and present problems that can not be overcome with ordinary handload-
ing tools. The writer has done at least a limited amount of experimenting with deep gas chccks and the results have been very unsatisfactory. It is impracticable, if not impossible, to get a tight enough assembly between the cups and the bullets to prevent some slippage between die two when the bullets arc fired, by using any lubricator and sizer or bullet sizing tool. If there is slippage between a deep gas check and the bullet, or between the jacket of a bullet and its core, the accuracy will be poor.
Gas checks can be put on bullets by tapping them on to the bullet bases with a stick but the usual way is to push the gas chccks onto the bullets as well as possible with the fingers or press the bases into the cups laid open side up on a table. The seating is completed when the bullets are forced, base first, through the bullet sizing die.
*49 Most gas chccks have slighdy rounded bases and when lubricating them in one of the lubricators and sizers, grease is apt to forcc its way under the bullet bases unless a recessed inside punch is used to close the gap between the rounded edge of the gas check and the top of the punch. Piain base bullets require an inside punch with a flat sur face. I expect that the next few years wiil find gas check cups made with flat bases, which is the proper way to make them although the present ones work all right.
Hollow Point Bullets, These bullets arc cast from the base and may be cither plain base or gas chcck. The hollow point is formed by a slender plug which passes through the base of the mould block, through the point end of the cavity into which it projects. The plug is inserted before the bullet metal is poured into the mould and is withdrawn before the mould is opened. To make such a mould, a drill bushing is necessary. This bushing takes the form of a steel bullet, exacdy the same shape and size as the mould cavity, with a hole the size of the drill passing through its center. The hole is drilled and reamed first and the bushing turned and ground on an arbor, so it will be concentric with the hole. The mould blocks are cherried in the usual manner and to a point where die bushing fits the cavity perfecdy; then the hole for the hollow point plug is drilled, die bushing serving to guide the drill. This is the only way a hollow point mould can be made or drilled to insure that the hollow point will be in the center of the bullet. Manufacturers can only make hollow point moulds for those bullets for which they have bushings, and they wiil not make these bushings for any bullet, simply to make up one or two moulds, as the bushings arc expensive to make properly. Bear in mind that a bullet, normally pointed, will have the point removed if the mould is made in hollow point form.
Hollow point, in common with hollow base bullets, arc a little less convenient to cast than solid bullets. It behooves the caster to work as rapidly as convenient when casting cither of them, as the metal must flow into a rather narrow space around the plugs and the plugs, being of small bulk, chill more rapidly than die rest of the mould. Hollow point plugs are slighdy tapered to permit their easy withdrawal.
Hollow point bullets are effective for hunting purposes. Their expansion depends upon their hardness, the velocity at which they arc driven, or more properly, the velocity at which they strike, and the depth and diameter of the hollow point. At low velocities, the bullets should be soft. On small game that is going to be eaten, solid bullets are usually best as hollow points destroy too much meat. On the larger animals, the bullets should be hard, with hollow points that are not too deep. If the hollow is too deep the bullet will expand too quickly, causing a large surface wound but lacking penetration; a shallower hollow will permit the point to expand but leave a heavier solid body behind the expanded point to push it on, thereby causing a smaller but deeper wound.
The depth of the hollow point in a cast bullet can be decreased by filing off the end of the hollow point plug, but as this plug is shortened, the weight of the bullet will be increased. Hollow pointing removes weight from the front end of the bullet and moves the center of gravity back toward the base, which is beneficial rather than detrimental to good accuracy. Some bullets that are not particularly accurate when cast solid, arc very accurate when cast with hollow points.
Hollow point cast bullets can not be depended upon to break up completely on impact as they can not be driven at high enough velocities to insure this. The safest bullets for use in settled communities are light weight, jacketed bullets with hollow points, driven at the highest velocities possible with safe pressures. Any attempt to make a cast bullet with a hollow point wide and deep enough to cause it to go to pieces upon impact with the ground, or any substantial object, would be of such poor ballistic shape that it would not be accuratc at other than short distances.
There is no reason for making a very deep hollow point 151 in a bullet. As the term implies the hollow should be in the point rather thar. in the body of the bullet. To determine how deep the hollow could be made in a plain base revolver bullet without danger of the bullet blowing through at the base, the hollow points of some bullets were deepened by drilling them out, a flat end drill being used to bottom the holes. The picture on Plate Xlli shows the result. As the hollow became too deep, the bullet slugged out of shape and finally the base blew out, blowing the tapered forward portion of the bullet out to a cylindrical form after which the gasses got around doe outside of the bullet and collapsed it. A base thickness of at least .100 inch should be left to prevent it from blowing out and with only this thickness the accuracy will be destroyed anyway. I repeat that hollows should be limited to the points of bullets.
An old trick and a good one for casting expanding point bullets with a mould for a solid bullet is as follows: Lay a strip of thin bond paper across the inside surface of the mould block in such a way that when the mould is dosed, the paper will form a septum or division in the point end of the bullet cavity. When the bullet is cast, the paper can be pulled out or torn off leaving a fine slit in the bullet point, blit preserving die original shape of the bullet. The drpth of the slit can be controlled by the location of the paper strip. If the bullets are soft and they are driven at a fairly high velocity there is a tendency for the points to open up in flight, especially if the slits are deep. To avoid this, the paper ctrips can be cut narrow and laid across the mould cavity in such a way that a small part of the nose or point of the bullet will be cast solid, the paper strip being entirely surrounded by lead as the bullet comes from the mould. The solid tip will hold the bullet together in flight but wdl not prevent the point from expanding on impact. By varying the bullet hardness and the depth and location of the slit, almost any degree of expansion may be obtained. The paper between the mould blocks will slighdy
152 enlarge the bullet, but as the enlargement will be equal on the opposing sides of the bullet, it can be sized without throwing it off center.
Now for a word about sizing cast bullets of any kind. Mould cavities are not perfecdy round, except by chance, although they are pretty close to it, and different bullet alloys shrink differendy on cooling. In casting bullets, the halves of the mould block are not always pressed together exacdy alike, especially when casting rapidly, so it is necessary to make the moulds so they will cast bullets slighdy over size, later sizing them to the correct diameter to remove the inequalities in them. This not infrequendy results in the removal of more metal from one side of the bullet than from the other. Sometimes one side of the bullet hardly touches the sizing die while the other is sheared off in a way that leads the reloader to believing that the sizing dies are way out of line, whereupon he sets up a loud howl that his bullet sizing contraption is no good. Far be it from me to poke fun at the inexperience of any reloader for while the mechanics of hand-loading are indeed simple, there are a multitude of litdc details that can not be learned in a day. Nevertheless, I am forced to remind the reader that howling is done with the mouth rather than the brain and while sizing dies and loading tools can't always be pcrfcct, they hit a pretty fair average. As this condition of "off-center" sizing of bullets is not uncommon, let's take a careful look at it.
When a bullet is fired, it passes through the barrel revolving around its center of form because it is held by the barrel, but when it emerges from the muzzle and is no longer supported, it rotates around the center of moss. (Center of gravity). If the center of form or shape and the center of mass or gravity arc not the same, the rotation of the bullet will be eccentric. If the eccentricity were the same in all bullets fired, the accuracy would be good in spite of the condition, but this is not likely to be the case. Therefore,
153 one of the problems in making any kind of bullets is to get these two centers to coincide and it is with this object that we size our cast bullets instead of shooting them just as they come from the mould. True, if we do use them as cast, the barrel will do the sizing but it may not do it always the same; one bullet may bear harder on one side than another, etc.
The diagram reproduced below will show why bullets are not necessarily off center because more metal is sheared off one side than the other. The drawing is, of course, grossly exaggerated, but will show die principle clearly. "A" represents the center o£ mass of the bullet as it comes from the mould and "B" the center of form and we want to get the two to coincide. When the bullet is forced through the sizing die, the side "D" bad litde or no metal removed
from it while the side "C" is sheared off. The bullet appears to have been forced off center, but actually it is not, and the point "A" has been moved over to "B" approximately. The difference between the two is not often sufficient to affect the accuracy at ranges at which cast bullets arc usually fired. It is better, theoretically, if the cast bullet is round to begin with and the removal of metal is equal on all sides, but bullet moulds can not be made to cast perfectly round bullets except by chance or at a prohibitive manufacturing cost. Then there is always shrinkage to contend 154 with. Swaged bullets can be made round and to the correct diameter to begin with and they only have to be sized to remove the small amount of metal that is squeezed out when the grooves are rolled into them, but not cast bullets.
Sizing Diameter. Now, about the diameter to which a bullet should be sized. Most hand books on reloading describe methods of measuring the groove diameters of barrels. They do so for the benefit of the fellow who has a special, obsolete, or other anomalous barrel, but it seems as though about fifty percent of the people who read the directions feel that they must measure their barrels before they can get a bullet mould, overlooking entirely the fact that bullet moulds are standardized articles and are not made specially for each barrel. The same holds true to a lesser degree with bullet sizing dies. If you have a modern rifle of any reputable make, there is no need of measuring your barrel. I refer particularly to rifles made in the United States. Even with the Krag and Model 1917 rifles, which vary more than an ordinary amount in their bore and groove dimensions, this holds true.
In revolvers, the barrel dimensions are not the sole governing factor in determining the bullet diameter, as the bullet must be large enough to receive some guiding support in the throat of the chamber. For example, .38 Special Colt Revolvers have a groove diameter of .354 inch, subject to manufacturing tolerances, but they use bullets measuring .358 inch in diameter. If a .354 inch bullet were used, it would receive little or no support in the throat of the chamber and its angular entrance into the barrel would be increased, to say nothing of the evil effects upon the bullet itself from the excessive reduction, of which we will have more later. The standard diameters of revolver bullets have been worked out over a period of time, more by practice than by theory and the novice who sticks to standard bullet diameters is making no mistake. Revolvers, with their separate rotating chambers, present an entirely different problem from rifles and pistols and the two should not be *55 confused.
Somewhere, somehow, the word got noised around that cast bullets for rifles had to be. .003 inch larger than the groove diameter of the barrel they were to be fired in. 1 don't know where it came from but it is the "bunk" and the worst part of it is that the sad news has penetrated deep into the sanctums where bullet moulds arc made. There are two very good reasons for making moulds to cast bullets a few thousandths of an inch over size, other than to true them up by sizing. If the cherries with which these moulds arc made are a trifle large, they can be re-sharpened more times which increases their useful life and decreases the tool cost. Also, it permits sizing the bullets a thousandth or so over standard size for the occasional barrel that may run a bit too large for standard diameter bullets. But there is no reason for carrying this too far, as has been done with some bullets.
Thirty caliber bullets, being the size most extensively used, may be taken as an example. The standard groove diameter of caliber .30 barrels is, and always has been, .308 inch. Some barrels in commercial production will run as large as .309 inch and on rare occasions, a little larger. If a .308 inch bullet is centered in a .309 inch barrel, only one half thousandth of an inch will be left on opposing sides of the bullet, (ignoring the expansion that takes place when the bullet is fired) an insignificant amount even with hard jacketed bullets. With lead alloy bullets which, at their hardest, are relatively soft and plastic, this difference in diameters is just about nothing. The correct diameter for flat base bullets for caliber .30 arms is and always has been .308 inch, which is perfecdy natural and obvious. Bullet moulds for such caliber used to be made to cast the bullets about .311 inch in diameter, although many of the older moulds will drop their bullets closer to .308 inch. This .3ir diameter allows three thousandths of an inch for variations in the cherrying of the moulds, wear of the cherry and 156 allows plenty of excess metal on the bullet for truing it up in a sizing die- Bullets seldom run more than a thousandth of an inch out of round as they come from the mould, so there is still a couple of thousandths for the reloader to play around with if he wishes or needs an over size bullet.
Apparendy, because bullets of this caliber were often cast as large as .311 inch, the idea has gotten around that bullets must be several thousandths of an inch larger than the standard groove diameter and most of the newer bullets cast large enough to size down to .311 inch, which means that they cast around .315 inch. These .311 inch bullets arc so large that they make the necks of the cartridges they arc loaded in too large to go into the chambers of some commercial rifles, Military chambers are purposely made a trifle large so the arms will surely function with dirty chambers and oversize cartridges, as both of these conditions are found under war time manufacture and service, con-scquendy, .3ir bullets will work in such chambers. When bullets arc made so large that they can not be loaded into standard chambers it certainly looks as if something was wrong, doesn't it? The common remedy for this fault is to size the bullet smaller, which seems simple enough at first glance, but in reality this is a make-shift remedy with certain serious faults. In the first place, if the diameter of the bullet is too large to begin with, the diameter of the ogive or nose is also too large for the throat or bullet seat of the barrel and this part of the bullet is not affected by any sizing operation. It not infrequently happens that, regardless of the sizing, these over size bullets have to be seated abnormally deep into the cases, in order to get the cartridges into the chamber, but this is not always a serious fault as far as their performance is concerned-
Bullets will size very nicely if the reduction in their size is not much over \7o of the bullet diameter. This means about .002 inch for caliber .22 bullets, .003 for .30 and .004 for .44 and 45 calibers. These reductions are approximate but if they are exceeded appreciably, the bullets may size irregularly, off center and often the lubrication grooves will 157 be closed up enough to prevent proper lubrication. It is not in the cards to size a bullet that casts .315 inch in diameter down to .308 inch, therefore; the groove diameter of the barrel is not the sole determining factor in sizing bullets; the limitations of the bullet itself must be taken into consideration.
There are a few plain base bullets that are designed to be shot as they are cast and without any sizing whatever, although they must be lubricatcd. These comments on bullet sizing, of course, have no reference or application to such bullets.
Most jacketed bullets consist of two parts; the jacket and the core. Both jacket and core are made separately and assembled to make the complete bullet. Numerous materials have been tried or used for making bullet jackets. Some bullets made in Europe have jackets of soft steel, heavily plated with copper. As the copper plating is more or less porous, such bullets are apt to rust under unfavorable climatic conditions. They are also rather hard on barrels.
The two jacketing materials most commonly used in the United States are cupro-nickel and gilding metal. The former is an alloy of copper and nickel as its name indicates, the nickel content being just about sufficient to give it a white or nickel appearance. Cupro-nickel was used almost entirely for bullet jackets up until the end of the World War. It had two serious disadvantages; it was tough stuff and difficult to manufacture and it had a further disadvantage of building up lumpy fouling in rifle barrels, particularly near the muzzle, when the velocity of the bullets exceeded about 2000 f.s. This metal fouling destroyed accuracy and was difficult to remove. If a rifle were fired long enough, the metal fouling would build up about so much and then shoot out, after which it would build up again. Firing a few bullets at very low velocity would usually take it out but the usual method was to eat it out with a special ammonia solution which, if fresh and not left in the barrel too long, would cat or dissolve the cupro-nickel without harming the steel. The safeguarding of the steel depended upon the presence of a sufficient amount of ammonia gas in the solution and if too much of the gas escaped, the solution would cause rapid rusting of the barrel. This made cupro-nickel bullets a nuisance to the shooter and efforts were made to find a remedy for meed 158 fouling.
The copper rotating bands on artillery projectiles also cause metal fouiing and the French, who by the way have been responsible for many advances in the field of ballistics, discovered that if tin foil was put into artillery ammunition, metal fouling could be prevented. The tin, vaporized by the heat of the burning powder, coatcd the bore and either due to its temporary molten state, its anti-friction properties or both, prevented the building up of lumpy fouling.
The DuPont Company utilized this idea and brought out their I.M.R. Nos. 15^2 and 17*4 powders, which had metallic tin incorporated in them. The use of these powders does overcome the lumpy fouling of cupro-nickel bullets, but they leave a coating of tin in the bore that is harder to remove than the nickel fouling.. This really is of small consequence, as the presence of the tin does no harm and takes the form of a thin uniform plating throughout the bore. It did raise the devil with the ammunition bovs for
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