I cast my own bullets for just about all my centerfire arms using a bottom-pour RCBS lead pot, and I usually weigh those bullets that will be used for competitive shooting. I allow one-half of one percent variation from average weight, so in the case of my .45-70 Sharps used for Black Powder Cartridge Rifle silhouette shooting, a Lyman 457193 bullet of about 20:1 alloy should weigh 412 grains, but a weight of 410 grains is acceptable. I was weighing a freshly cast batch the other day when I came across one bullet that didn't even make 400 grains. It looked OK on the outside, but I knew it had an internal void so I decided to cut it open. It is very common for cast lead bullets to have small internal voids, but I doubt this one would have shot all that well:
I think it must have been one of the first ones cast, before the mould had a chance to really get up to temperature. The void is large and passes nearly all the way across the width of the bullet. Voids can be caused by any number of errors, including casting speed, temperature of mould and/or alloy, or just technique. This void is much worse than usual, and that is why I like to use my electronic scale to find these bad ones and send them back to the lead pot.
I have often wondered if commercial cast lead bullets exhibit many flaws. Strangely enough, the smaller bullets I cast, such as 158 grain .38 Special caliber or 115 grain .32-20 bullets don't vary enough to make weighing worthwhile.
SHASTA
