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Bullet Sizes & Weights – How to Vary Them
The bullet diameters and weights presented in this list are based on the use of Taracorp’s Lawrence Magnum bullet alloy (2% tin, 6% antimony, 1/4% arsenic, 91.75% lead).
Bullet diameters and weights will vary considerably depending on the lead casting alloy used. This variation can be as much as 1/2% on the diameter, and 8% on the weight among the most commonly used casting alloys. For example, a .358-158 grain bullet might show a diameter variation of .002", and a 13 grain difference in weight.
Of the most commonly used alloys, wheel weights (.5% tin, 4% antimony, 95% lead) will produce bullets having the smallest diameter and heaviest weight, with such bullets running approximately 1/3% smaller in diameter and 3% heavier than bullets cast with Taracorp's metal. Linotype will produce bullets with the largest diameter and lightest weights. This alloy will produce bullets approximately 1/10% larger and 3% lighter than Taracorp. Other alloys of tin and antimony, with antimony content above 5%, will produce bullets with diameters and weights falling between those cast f rom wheel weights and linotype.
Alloys containing little or no antimony will cast considerably smaller than wheel weights and in some cases will produce bullets too small for adequate sizing.
Within the limitations given above, the weight and diameter of a cast bullet can be adjusted by varying the
alloy’s antimony content.
The size and weight of bullets of a given alloy will also vary according to casting temperature. Higher temperatures will result in greater shrinkage as the bullet cools, thereby producing a slightly smaller and lighter bullet than one cast of the same alloy at a lower temperature.
SAECO has adopted the tapered form of gas check heel to minimize problems encountered with the use of various alloys and gas checks. SAECO bullets are designed to properly maintain the gas checks when cast with Lawrence Magnum Bullet Metal or linotype. Alloys producing smaller diameters may result in gas checks not seating properly. Bullet weights listed for gas check designs include the gas check weight.
Bevel Base Bullets
SAECO Bevel Base bullets have a slight bevel at the base of the bullet. This bevel helps guide the bullet into the cartridge case. A benefit of using bevel base bullets is that the case will require minimal bellmouthing, and have a longer case life. Bevel base bullets are of course easier to seat.