Failure of Bullets to Drop From the Mould. If the mould requires only slight jarring to make the bullets drop out, the condition can be ignored as a slight amount of "sticking" is unavoidable. The bullet usually persists in sticking in one certain half of the mould. Some operators tap die inside edge of that block with their stick—diis is pretty apt to spring that half or cause it to warp open in time. Others tap the end of the handle in which halt the bullet is stuck—this is apt to split that handle in time, but it can readily be replaced.
If one has to resort to pouncing to get the bullets out there is something wrong and the mould will probably have to be returned to the manufacturer to have the defect remedied. The slightest damage to the sharp edges of the mould cavity will form a burr that will hold the bullets in and only an experienced mechanic can remove such a burr without damage to the rnouid. The average individual should not tamper with mould cavities in any way. Any manufacturer will correct a new mould that is at fault without charge, so it seems foolish to take a chance on ruining a four or five dollar mould.
Failure of Bullets to Fill Out. This is usually due to the mould, the metal or both being too cola. If the mould is too cold the metal will solidify before it has time to flow into ail the corners. The net result will be the same if the metal is not hot enough. Sometimes mould 19a blocks fit so closely together that the air cannot escape and with such a mould it is impossible to get good bullets unless the mould is "vented." Venting is done with a fine three-cornered file, with which shallow grooves are filed across the inside face of the mould blocks in such a way that the air may escape from the points where the bullet does not fill out properly. If the vents are filed too deep
An Imperfect bullet and the -venting necessary to correct «1« fault*.
the bullet metal may flow into them when the mould and metal arc very hot, but this does no harm as the projecting slivers will be sheared off when the bullet is sized. Venting can be done by anyone who is handy with a file but the file may slip and there is a good possibility that the file will burr the edge of the cavity. A vented mould is shown on this page which will serve better than a description of how the job is done. But remember—if a new mould does not cast good bullets the manufacturer will either vent it for you or replace itl
Bullets Out of Round. Ehie to shrinkage of some alloys when they cool, and to small manufacturing tolerances in the moulds, bullets may be a thousandth of an
inch or so out of round as they come from the mould. They are purposely cast a litde over size to permit truing them up in a sizing die of the correct diameter. If the variation in diameter is greater than two or three thousandths of an inch it may be due to a faulty mould, 193 burred or enlarged dowel pin holes or to the presence of specks of lead on the inside faces of the mould blocks. Sometimes when dropping a defective bullet from the mould into the melting pot, lead will splash upward and small drops get caught between the mould blocks. These flatten when the mould is closed but hold the block? ap-irr enough to cause the bullets to be out of round. Such lead flakes arc easily removed with a sharp knife.
Fins on Bullets. Mould blocks do not fit together properly or sprue cuttcr is not flat against top of mould blocks. If sprue cutter is loose tighten the pivot screw. If the sprue cuttcr is bent, remove it and try to straighten it with a light hammer. Then file the under surface flat, put it back on the mould and try it. If you cannot correct the difficulty in this way you will have to get a new sprue cutter. Burrs or raised metal around the dowel pin holes can be detected with a straight edge, they are easily removed with a flat file, but care should be taken not to file across any part of the mould cavity.
Failure of Two Halves of the Mould Cavity to Coincide. The dowel pin holes are enlarged and the mould will have to be returned to the factory.
Frosted Bullets. When bullet metal cools it shows under the microscope as a crystalline formation. The size of the crystals depends upon the rate of cooling. If the metal cools quickly the crystals are small; if it cools slowly they are large. Bullets that solidify quickly in the mould will, therefore, usually have a bright shiny appearance bui where the mould and the bullet metal are very hot and the metal coo's slowly, the crystals will be so large that the bullet will have a frosted appearance. This difference in crystal size docs no harm and has no affect on the per formance of the bullet. If the mould and metal are allowed to cool down a litde it will disappear but it must be borne in mind that some bullets with narrow bands, and especially bullets with hollow points and hollow bases, 194 must cftfntimes be cast with somewhat hotter metal than normal.
Folds and Seams. Either die mould or the metal is too cool.
Lead Smears On Tod Surface of Mould Blocks.
Usually caused by striking olf the sprue when the mould
A—Bullet not filled oat. Metal or mould too coj.f. 3. Effect o( ffrease or oil In mould. C. Two halve? of Imllet do not match. Mould has excessive "shuck". 0. Perfect Bullet.
is very hot and before the metal solidifies. This lead can ■usually be removed with a sharp knife when the mould is cold. It can also be removed with mercury. Be careful not to damage the edge of the cavity when you go to scraping around it with a sharp knife.
Elliptical or Lop-sided Bases. Generally confined to very soft builets and caused by the ba.se of the bullet
being forced to one side when the sprue cutter is struck. See that the cutting edge of the cutter is sharp. It can be "charper.rd with a counter-sink turned with the fingers. If a ¿oft alloy is used this defect can be reduced by closing the sprue cutter just far enough to allow the metal to be r*ourcd.
Hollows Iij Base of Bullet. These occur in bullets that are c-it v/tih a very hot mould and metal. The more slowly a bullet cools the coarser the grain structure will be and the more chancc of the mctnl breaking off at 195 the sprue. This leaves litde crystalized depressions in the bullet bases. They do no harm other than to slightly reduce the weights of the bullets and only affect the accuracy to the extent that the weight cf the bullet afreets it.
Eullet moulds are ordinarily made from blocks of malleable iron. These blocks are machined to the proper shape and size and the interior surfaces carefully ground so that they will fit perfccdy together. The two halves of the mould arc then clamped together and are drilled through at the proper points fcr the dowel pins and the cor res pom ling holes in which the dowels are to fit. This insures perfect alignment of th< two halves of the mould. A hole is then drilled in such a way that half of it is in each ha if of the mould blcck. After this the two halves of the block arc brought together against a revolving cherry which is a spccial form of reamer that cuts a cavity the exact shape of the builet. This sounds like a simple process and so it is to tell it on paper, but the operation is one calling for special skill and experience.
In the first place, a cherry is one of the most difficult reamers to make and frequendy a lot of "fussing" is necessary before a new one will cut right. In making a cherry the stock is turned and ground to the shape of the bullet and to a size that will cut a cavity of the proper size. Ordinarily a cherry will not cut a cavity quite as large as itself unless allowed to run for an excessive length of time, and allowance must be made for this as well as for a possible shrinkage of the builet alloy used. After thi cherry is shaped the grooves must be milled in it longitudinally after which the real hard work begins for the tool maker. Merely cutting the grooves in the cherry will not leave it in condition so that it will cut, the ridges muse be backcd off before the cherry will cut, as the cutting edges or faccs mu.it always be the wides: parts of the projections. This 'backing off' is all careful hand work and the amount that the edges are backed off depends 196 upon the kind of metal the cherry is to be used on. For example, a cherry made for cutting cavities in malleable iron would not be satisfactory for use in steel or bronze and sometimes a cherry must be worked over several times before it will cut smoothly and without chattering. Even if the clearance is correct a cherry will chatter at times. If this happens when the cavity is nearly finished, both faces of the blocks must be reground and the cavity recut or the blocks may be cherried out for a larger caliber of bullet.
The older type bullet moulds had no detachable blocks, each half of the block being integral with one of the handles. The oldest ones had no dowel pins, but they were in general satisfactory. The objection to this type of mould was largely a manufacturing one for it was necessary to carefully fit the mould blocks before they were cherried and if anything went wrong with the cherrying the entire mould had to be scrapped. Furthermore, there was a tendency for the castings to warp under the influence of heat, throwing the two halves of the mould out of alignment. However, in spite of this many of these old moulds, including those that have no dowel pins, are still in satisfactory condition after years of use.
With detachable blocks, cherrying is more uniform from one mould to another than it used to be with the old style solid block moulds. The latter, being hinged and closing on an arc, had a tendency to squeeze the cherry away from the hinge and when diis happened there wasn't much to do but pitch the mould in the creek. Nevertheless, most of the old style moulds that finally got out of the factory were pretty good and some of them were excellent.
Hard spots in the blocks make trouble and blow holes in the castings may cause uneven cutting and necessitate recherrying. It is not possible by ordinary production methods to cut two cavities exactly alike except by chance but the differences between cavities cut with the same
Usual "set-up" for proper casting of bullets over the gas-range.
Method ol casting necessary to get perfect and full bullets.
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