How close is close enough?

[kentuckycajun]

I just got 2000 new Starline brass in .357, and have a few questions before I waste any unnessesary time prepping them.

I've found the general concensus here is to size before trimming. I ran about 500 through full lenght resizing (and yes, they did stretch about .002 - .003). I measured EVERY one (I have a great job where I can do this at work in my spare time - nice to get paid while I do this). They vary in length from 1.275 up to 1.283. Is this good for new brass?

I want to trim them all to the same length, and to have them all perfect at 1.275 would be optimal, but unrealistic.

So, how close is close enough? +/- .001? +/- .002?

Hope I'm posting in the right place - sorry if it's not.

[GP100man]

I set my calipers up as a go -no-go gage at 1.280 alot will pass !!!

After a loadin I trimm with the lee system on a drill press at 1.278 & they stabilize for a good while !!

[500bfrman]

i never even mess with new brass.

[kentuckycajun]

What I'm getting at is, if I pick a midpoint (say 1.279) to set my flare and roll crimp dies with, that will give me +/- .004 variance.
Will .004 make that much of a difference in the consistency of the crimp?
Or should I trim them to a closer tolerance?

[462]

Unfortunately, I don't get paid to do brass prep, but my time is my own, so I set about trimming every piece of .357 and .38 brass I have. I figured that having them all the same length would produce the most consistent crimp. Since straight-wall handgun brass doesn't grow, unlike bottle-necked rifle brass, it's a one-time job.

I even started trimming .45 ACP cases but soon discovered than they don't need it. All of them were under maximum length, regardless of headstamp.

Two-thousand is a lot, but I'd trim them.

[GP100man]

With the naked eye u will not be able to see the difference , with hard boolits ya may be able to feel it , but to see it you`ll have to get into the .010-.015 range .

I tried a batch of .010-.012different length brass (in the same batch) over the chronograph& it made little sd difference

But when adjusted to the longer brass & the crimp went lite on some the sd was alot wider !!!!

Testing was done with h-110 powder.

[kentuckycajun]

Thanks GP, that's what I was lookin for. I don't have a chrono just yet - hopefully soon. Guess I'll try to get them all to within 1 or 2 thous (not at one sitting, of course)
Incidently, I'm shooting a GP-100 also - 6" SS w/ Hogue grips. Absolutely LOVE it!! Accuracy is pretty good right now, but I know I can do better.