Thread: trimmin 223 brass for ar15

im curious, whatdo you guys trim your brass to? iv heard lots of different things, so post what you trim to and why please

1.750" I use a dillon RT1200 trimmer for this purpose, anything shorter I don't worry about, and only care about stuff that's longer.

My .223 is single shot,so I either use my Lyman hand cranker,or here lately I've been using a neck sizer since it was all fired in my gun.Neck sizing not a good diea for AR tho.
I trim to 1.750,per the books,but will use some a little shorter also.
I receently pulled apart some factory ammo that my gun woould not fire for some reason,and the factory ammo was way shorter than mine,by about .040". You run into a lot of oddities when reloading.

I too use the Dillon RT1200 trimmer. EVERY piece of .223 brass goes through the trimmer which also sizes it. I don't bother sorting short/long cases. The long ones get knocked down and the short ones will eventually grow until they need to be trimmed too so everything goes through.

Trimming is essential if you are crimping in your bullet seater die. Lack of uniform case length will yield uneven crimps. Short cases will not crimp enough but that's not as large a problem as too long a case. Long cases, when being crimped in the seater die, can get bulges where you don't want them and then the round may not chamber fully. Not a good thing in an AR as it stops the action and they aren't always easy to extract. For those that don't crimp it's not as big a deal but it's still a good idea to have uniform case lengths. Having a nice square case mouth doesn't hurt accuracy either.

before i got a lathe type case trimmer, i accidently trimmed some cases down to 1.730 (at max), i marked them and set them aside incase they were unsafe, are these useable?

Originally Posted by Dizle

before i got a lathe type case trimmer, i accidently trimmed some cases down to 1.730 (at max), i marked them and set them aside incase they were unsafe, are these useable?

Still usable. May not get the case mouth to line up with cannelure if using such a bullet and loading to 2.260" OAL. You'll have less neck holding on to the bullet but not enough to really matter. Extra Long cases are the ones that cause most problems.

FWIW, RCBS X-Dies call for a severe shortening of the case for the first time loading and then no trim necessary (or so they say) from then on.

1.750 =/- .002

Roman u mean 1.750 +.000/-.020 or -.002?