size up or down for brass jackets?

[BT Sniper]

Curious as to everyones thoughts as to the differences between sizing up a brass cartridge vs. sizing down for making bullets.

Example the 40 S&W for .429 vs .410 and the 9mm for .401 vs. .357?

Accuracy, jacket wall consistancy, simplisity, no difference or personal preferance, etc., etc..........

Thanks guys keep the projects coming,

Brian

[MIBULLETS]

I don't think it matters as long as the finished size is correct. On most cases if you have to expand it much the case head will be undersized and possibly not centered in the bullet base. I would think best performance would be from a case that already is the correct size or one that has been sized properly. One possible negative would be that you may be work hardening the brass some, but you are probably annealing it anyway. Just my thoughts.

[bohica2xo]

Either may work, depending on caliber, and desired bullet weight.

I reduce 9mm / 30 Tokarev / etc for .358 rifle bullets. I have drawn down 40 S&W for .358's as well, but it takes two passes.

40 S&W works out great as a .429 bullet without reducing.

The important part is having the jacket smaller than the finished bullet. This way the jacket is expanded in forming, and is actually in tension around the lead core. To that end I reduce 9mm's to .350 before making bullets.

I reduce 40 S&W to .395 for making 10mm rifle bullets. We call it a 10x51 - just a 308 necked up to 40 cal.

B.

[kawalekm]

Hi BT
Have you ever heard of the term "parsimony analysis"? Basicly a term used in design processes and evaulation that refers to the relative complexity of actions that lead to a final result, in this case a finished bullet.

In other words, a high tech version of Murphy's law, if anything can go wrong, it will go wrong. Applying this to making bullets, the more steps you have to make a bullet, the more likely it is that something will go wrong with it and reduce performance. It's safe to assume the more steps there are in a bullet making process, the more likely that finished bullet will have some kind of degrading defect. If your steps are anneal, core seat, bullet swage, you're likely to produce a better bullet than if you anneal, draw, core seat, bullet swage; with everything else being equal.

I ordered a new set of 40 caliber bullet dies that will be arriving shortly. I suppose I can test this first hand by making 40 caliber bullets out of 9mm brass, and by first drawing down .40S&W brass. Intuitively, I'd expect the 9mm jacket bullets to shoot better than the 40's. One more thing on my list!
Michael

[BT Sniper]

Michael,

I haven't heard of parsimony analysis but it makes sence. Along the lines of keep it simple stupid.

I imagine the 9mms will work great for the 40 bullet. I have been collecting brass for this as well but don't have the dies yet. I can see trying to keep up with you is going to be a challenge as I just ordered the .357 dies. Anyone using the CH .308 swage dies? Also have a set of them on the way. Not sure what I'll use for jackets, may attempt copper tubing.

Michael what did you use to reduce the .223 case to .357? Have you been doing much shooting with your bullets?

More latter,

Brian