OT- Trimmed brass

[Andrew]

How close is "close"?

I, awhile back, set up my trimmer finally for some .45LC trimming thanks to odinohi. I was able to sneak some Winchester brass from the Midway site and took several out to check for case length. They had some thousandths of difference between them so I split the lot in half and trimmed one pile and loaded the other(the stumps won't know any different). After all was said and done I had 50pcs sitting there all the same length. My question is, what do you guys look for as far as "same" is concerned? All mine, according to my Frankford Arsenal, caliper are within .001" of each other which as far as my shooting goes is the same as perfect.

What tolerance do you guys look for and is there any rule of thumb when it comes to this?

[Hobie]

Most usually when trimming new brass I use the trim-to-length measurement from the manual I'm using. It seems that about 95% of all cases (all cartridges) I might take off .001" but mostly squares the case mouths. SOME lots will take off of brass ARE noticeably longer than the trim-to-length but not many. A very few will have cases noticeably shorter than the trim-to-length. Most straight cases don't need additional trimming for a while while some brass and some case design seem to grow with every shooting.

[Sixgun]

Andrew,
In addition to what Hobie said, I might add that my pistol calibered straight wall cases never get trimmed. I don't even check 'em. They grow little and will split/crack before they grow. I don't care what Brian Pearce says, trimming these cases are not worth the aggravation as guns chambered in these calibers have generous tolerences.

I do check my levergun rifle cases such as 30-30, 32-40, 38-55, 40-65, 45-70, 40-82, etc. but these cases (IF shot in guns in excellent mechanical condition with little to no excessive headspace) also do not grow (or grow little) if used with cast bullets at normal pressures. I keep these at + or - .005 of industry standard dimensions.

Where I really pay attention is my .257 Roberts, .223, 22-250, .219 Zipper, 300 mag and other high pressure cartridges that use jacketed bullets at high pressures all combined with "accuracy on demand". These cases will be trimmed every time and kept "on the money". If I want to bust a 3" dot at 500 meters, the bullets had better hit it. (well, the 219 Zipper at 300 meters )

[J Miller]

Ditto to what Hobie said. I'll add that with the 45 Colt cases I've bought in recent years they barely make minimum length.
Max length is 1.285"
Original trim length is 1.280"
Some manuals list the trim to length as 1.275"

I've purchased new unprimed Winchester ammo that has cases that vary from below the shorter trim to length, to some that were way over the max length.
Too long is a pain cos you gotta trim them a lot. Too short is a pain because they never ever are long enough.

My tolerances are basically to get the cases as close as I can. I set my caliper to the length I want then lock the jaws, pick a 'too long' case and gradually trim it till it will just fit in the jaws of the caliper. Then I lock the trimmer and and run them all. Those that do not get trimmed are tossed into a separate tray to be measured again. Those that do trim get chamfered inside and out and boxed for loading.
Oh, I trim after I size the cases. They shrink lengthwise when you shoot them, and it helps even out the new unfired ones too.

Edited to add:
You cannot get a consistent crimp with inconsistent case lengths. It's impossible. Especially if you use bullets with crimp groves. The closer the cases are to the same length the more consistent the crimp.

Joe

[Ysabel Kid]

Within 0.001" for the straight-walled .45 Colt? You are there buddy! As Sixgun said, no need to sweat that difference at all. I'd be stunned if you saw any difference when using the rounds!

[fordwannabe]

I have become very lazy I guess I bought the lee zip trimmer cutters in lots of calibers and I just run them through on my electric drill. It seems to work very consistently and for the most part my Lyman manual trimmer and my Lyman power trimmer don't get used much. My thought is as long as they are a consistent length who cares..and they are consistent. Tom

[Buck Elliott]

Yup -- consistency is the key... within limits. I usually check new .45 Colt cases, and trim them to 1.280", if they're longer than that. If they're shorter (usually by no more than .005") they'll 'grow' some, over time.

I use a relatively healthy crimp, for use in leverguns as well as 6-shooters, and for the REAL barn-burners, I use a very heavy crimp, in old FC cases, which seem to last almost forever.

[Andrew]

Well I figured as much but it's always good to ask. I wasn't aware of a specific trim length on cases although it makes sense. Don't know how I missed that one in all my loading learning.

Joe, you are right. I had them things crimping all over the place the last batch I loaded of the Magtech brass. I am looking forward to some consistency.

I have the non-trimmed Win brass loaded with 5.5gr of Clays and a 200gr LRN and will load the trimmed stuff with the same. Hopefully I can get a portion of them on paper and see if there is a real difference. I'll probably waste them on having fun though.

Thanks guys.

[Charles]

I use a file trim die and have no notion of the final length. I really am only concerned about having a nice square case mouth. I don't trim cases for general plinking ammo, not worth the bother.