View Full Version : Case Length Tolerance?

09-13-2014, 05:30 PM
I just finished de-priming a bunch of my 7mm Rem mag brass. I'm not quite set up to carry on with the loading process, but just for giggles I checked some case lengths.

My manuals call for 2.500" for case length. I got measurements between 2.487" up to 2.508". At what point do I need to start trimming the brass and should I toss anything that is under the 2.500"?

This is Remington Core-Lokt brass.

Lee Enfield
09-13-2014, 06:14 PM
As long as you get a proper "hold" on the bullet when seated you can use the case even if it is a little short, well I do that in .223 all the time. I trim mine a little short so they don't touch the length gauge for the calibre I am reloading and don't seem to have a problem.

I use the Lyman E-ZEE Case Length Guide as a go or no go gauge. If they fit, good to go otherwise trim so they do fit. I find the guide is worth buying as it makes measuring faster than using the Mitutoyo caliper for each measurement.

Rory McCanuck
09-13-2014, 07:42 PM
2.500" is safe in everything. 2.501" may not be.
Trim them down to 2.490"
Shorter is alright.

09-13-2014, 08:50 PM
2.500" is safe in everything. 2.501" may not be.
Trim them down to 2.490"
Shorter is alright.

This info is correct.

Does your manual list a max length and a trim to length?

09-13-2014, 09:31 PM
Just max length iirc. I can double check tomorrow. Thanks for the info so far folks. :)

09-15-2014, 01:27 PM
3.5" is way out of spec. Definitely trim an inch off of that. I know its a typo though.

You're better off short than long, that's pretty much the rule. Check the seating depth, that's what's important.

09-15-2014, 03:32 PM
Good catch on the typo. Thanks! LOL :)

09-20-2014, 03:53 PM
Only one of my three manuals lists a Trim To length. That's that's the Lyman book and it says 2.490. I also have Modern Reloadng second edition and the Noseler Reloading Guide 6. The old (circa 1995) Hornady manual I have a PDF file of also says 2.490 as a Trim To length. Guess that's the length I'll use. I'm also going to order that E-Z trim gauge that Lee Enfield mentioned. :)

Thanks for the tips every one.

road kill
09-21-2014, 08:43 AM
Most of my old reloading books list the max case length and a trim to length. The trim to length will usually allow several reloads before trimming is required again. God i hate trimming, i think santa is going to bring me a power trimmer of some king this year.

09-21-2014, 02:19 PM
I've already been looking at the power trimmer attachment. LOL.

I've also been looking hard at the RCBS 3 way trimmer attachment. Trims, chamfers and deburs all in one go. My hand chamfer/debur tool is a pain in the arse.

Geez, I haven't loaded a single round yet. I'm only in the case prep stage and already I'm eyeballing stuff to make my life easier. Either I'm really lazy or falling hard into the addiction...

09-22-2014, 07:03 AM
Sinclairs makes "Chamber Length Gauges". Caliber-specific, cheap, and super easy to use. By sacrificing one brass (trim it real short) you can exactly measure the length of your chamber. Then you don't have to guess at trim-to lengths and such. Some chambers are longer than spec, in which case you may not have to trim as soon, and should a chamber be almost "short", you know it and can trim accordingly.
Just be warned, if you haven't shopped at Sinclairs before, a little looking around can burn up a pile of money very quickly......

09-22-2014, 08:04 AM
I use the "Lee Cutter & Lock Stud (http://leeprecision.com/cutter-lock-stud.html)" and chuck it in my drill press.