Brass Trimming

[D Scott]

Hi I have been doing some reloading for a year or so now, my question is when some of your brass starts to creep up on the SAMMI specs for max overall length, what is the best way to go, trim only the long ones as you need to or trim the whole batch to a uniform length? any thoughts ? thanks Scott

 

[fj40mojo]

Trim all to uniform length. I generally go .010" under the nominal size.

 

[justgoto]

or trim the whole batch to a uniform length? any thoughts ?

I trim mine each and every loading to "a uniform length". My cartridges are not only uniform to the ones in the same batch; but all batches are uniform to each other.

 

[Greyfox]

I will chamfer new Lapua brass, fire once, then trim and chamfer to minimum spec. I will then shoot until it is about .004" longer, then trim.

 

[D Scott]

thanks gun)

 

[D Scott]

so in general what seems to be more accurate brass thats trimmed just to fit or brass that's a little shorter? which side is better to err on ?lightbulb

 

[Greyfox]

I have not seen differences in performance when length fell within specification. A thou shorter is OK and might give you another load before having to trim again, but not critical. I do make it a point to make sure all my brass is the same length in a given batch of reloads, for consistancy puposes.

 

[Kevin Thomas]

so in general what seems to be more accurate brass thats trimmed just to fit or brass that's a little shorter? which side is better to err on ?lightbulb

D Scott,

Trimming is a safety issue for cases, not really an accuracy factor. You'll see cases being trimmed .010" to .015" below the SAAMI or CIP max lenghts listed, with virtually no difference in accuracy. The issue here is to keep the case mouth from being pinched into the bullet when chambering the round, thus kicking pressures up with potentially serious consequences. In most applications I can think of, aside from those where a crimp is involved, accuracy isn't affected in the slightest if the cases vary a bit, just so long as they're below that listed maximum. Don't get too hung up on this one, just keep 'em under that max length, and you're good.

 

[D Scott]

Thanks for the advice Kevin I appreciate the feedback Scott

 

[gator44266]

Question, I trim my brass before sizing but I've heard some guys say they trim after sizing could someone please explain the difference. Thanks

 

[Kevin Thomas]

It depends on the trimmer you're using, but some of them (Gracey, Giraud) need sized brass to trim properly. The process of resizing can change the length of a case all by itself, since this is something of a draw process. For the most part, it's rather slight, but it can make a measureable change. For almost all applications, I'd say size first, trim afterwards.

 

[gator44266]

Thanks Kevin thats how I'll do it from now on,I use an RCBS trim mate,I havn't been reloading very long and its amazing how I learn something new everyday.