Hello,

I am just new at this casting business, so please excuse me if some of my inquiries sound dumb. I just bought a RCBS mould in .45 201 gr swc on the box it says .452 however my bullets come out at .451 and 207gr. I am using wheel weights as my source of lead. My question is this why? From what I read wheel weight are just about the right hardness for casting bullets to the correct size and weight.

Sam

Different lead alloys will have a different rate of shrink on cooling making the bullets smaller than the mold. WW's are sometimes a PITA. I get a couple hundred pounds at a time, melt them in 25# (or so) batches in the pot and cast into ingots. I keep each batch of ingots separate by marking them with a number punch. When I go to cast bullets, I pull an ingot from each lot of those cast from the raw WW's. It does help keep things more consistent.

Other thing you can try is adding some tin or antimony, may help fill the mold better. Other option is to lapp it. For what it's worth, I have a couple RCBS molds and they threw on the small side too, both have been lapped.

Small differences in diameter are VERY hard to measure accurately. A couple thousands isn't worth worrying about. If you want a larger diameter you might try linotype.

Weight depends on lead content. That varies in wheelweights. Linotype bullets would weigh less. Pure lead bullets would weight more.

Wheelweights are ok for slow bullets but with high powder charges accuracy compared to linotype will suffer.

The dimensions and weight of cast bullets are based on the alloy the mould manufacturer uses as a standard. Lyman moulds use their #2 alloy as a standard and even they have admitted their alloy, as prepared in a foundry, varies slightly in composition and from lot to lot. The same is true with ww's. The composition of ww's vary considerably even before we turn them into ingots. The point being that home cast bullets will rarely meet the specifications listed on the mould label. As long as we cast good bullets using our alloy that are consistent in dimensions and weight, the bullets will still perform well.

Thanks guys,

Like I said I am very new to this game.

Sam

BTW, I prefer to run my cast bullets .0005" to .0015" over bore diameter for best accuracy. I also don't drive my cast bullets at top end of the velocity chart, mid to low range seems to give the best accuracy and performance. I also prefer a softer alloy especially in hunting bullets where performance must be taken into account. For this reason it is best to use a heavier bullet traveling at lower speeds and with a flat point. Another thing is, the more bearing surface you have (contact between bullet and barrel) generally will be a more accurate bullet. Best thing you can do is get a lead hardness tester, micrometer and scale, then try to keep all your batches as uniform as possible for hardness, as-cast diameter and weight. You'll have some variations but the lower you can keep the range, the more uniform the accuracy and performance will be. Oh, generally slower burning powders will give you the best accuracy too.