223 / 5.56 trim length?

Nathan · March 16, 2013, 12:33 PM

Currently my 223 reloading method related to case trimming is to:
- FL size & decap
- measure to 1.760" and anything long goes to the trim process
- trim those to 1.750"

I think I have to trim some at every loading. This is my issue. Can't I trim once per like 5 loadings?

My headspace spec is fired -0.002" for the shortest chamber I load for. My sized HS dimension varies +/-0.003.

So, I ask...Are you trimming to 1.750" or have you found 1.740" or 1.730" work better for you?

243winxb · March 16, 2013, 01:29 PM

I trim to 1.750" when the batch/lot gets a few over maximum. Mixed brass grows at different rates, so this may not work for you. The RCBS X die instruction say to trim to 1.740" or -.020" under maximum. Neck tension is reduced more with shorter necks, how much i do not know. This SAAMI drawing shows a minimum case* length of 1.730" http://www.saami.org/PubResources/CC...0Remington.pdf

oldpapps · March 16, 2013, 05:05 PM

For me all .223/5.56s are always size/deprime, clean a second time, check the web for roughness and trimmed. I don't like to use the word 'always', but this time it does apply.

Brass 'grows' at different rates depending upon, among other things, loading pressures, the chamber fired in and how hard the brass may be.

A wile back I was running a long term experiment with a .223/5.56 based round and short trimming and just how many loading before the need to trim again. Unfortunately, I sold that weapon before I completed the test run. But I was at 14 loadings. These were not barn burner loads in 300 AAC Blackout.

My suggestion is select a small batch, over 15 for a statistically valid results. Over trim to a set length, load and fire. Keep doing this until you reach a conclusion. If you don't keep records of each loading and length after firing, nothing will be determined.

Enjoy and be safe,

OSOK

oryx · March 16, 2013, 09:22 PM

.223 does not headspace off the mouth that gets trimmed, but off he shoulder. You can trim once every 5 times if you want, but run risks doing it without checking. I can't imagine trimming to a length of 1.730" thats a pretty extreme trim in my opinion. Trimming to 1.750" is plenty and should allow multiple firings before reaching max, but I usually check.
Brass prep used to be a hassle to me but I now enjoy it along with all of the other steps of reloading. I pretty much do something reloading related daily and sometimes prep for days paying attention to details

March 16, 2013, 12:33 PM	#1
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,334	223 / 5.56 trim length? Currently my 223 reloading method related to case trimming is to: - FL size & decap - measure to 1.760" and anything long goes to the trim process - trim those to 1.750" I think I have to trim some at every loading. This is my issue. Can't I trim once per like 5 loadings? My headspace spec is fired -0.002" for the shortest chamber I load for. My sized HS dimension varies +/-0.003. So, I ask...Are you trimming to 1.750" or have you found 1.740" or 1.730" work better for you?

March 16, 2013, 01:29 PM	#2
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	223 Rem Trim Length I trim to 1.750" when the batch/lot gets a few over maximum. Mixed brass grows at different rates, so this may not work for you. The RCBS X die instruction say to trim to 1.740" or -.020" under maximum. Neck tension is reduced more with shorter necks, how much i do not know. This SAAMI drawing shows a minimum case* length of 1.730" http://www.saami.org/PubResources/CC...0Remington.pdf Last edited by 243winxb; March 18, 2013 at 08:32 AM. Reason: change "trim" to "case" *

March 16, 2013, 05:05 PM	#3
oldpapps Senior Member Join Date: September 22, 2011 Location: Middle America Posts: 518	For me all .223/5.56s are always size/deprime, clean a second time, check the web for roughness and trimmed. I don't like to use the word 'always', but this time it does apply. Brass 'grows' at different rates depending upon, among other things, loading pressures, the chamber fired in and how hard the brass may be. A wile back I was running a long term experiment with a .223/5.56 based round and short trimming and just how many loading before the need to trim again. Unfortunately, I sold that weapon before I completed the test run. But I was at 14 loadings. These were not barn burner loads in 300 AAC Blackout. My suggestion is select a small batch, over 15 for a statistically valid results. Over trim to a set length, load and fire. Keep doing this until you reach a conclusion. If you don't keep records of each loading and length after firing, nothing will be determined. Enjoy and be safe, OSOK

March 16, 2013, 09:22 PM	#4
oryx Senior Member Join Date: December 26, 2008 Posts: 142	.223 does not headspace off the mouth that gets trimmed, but off he shoulder. You can trim once every 5 times if you want, but run risks doing it without checking. I can't imagine trimming to a length of 1.730" thats a pretty extreme trim in my opinion. Trimming to 1.750" is plenty and should allow multiple firings before reaching max, but I usually check. Brass prep used to be a hassle to me but I now enjoy it along with all of the other steps of reloading. I pretty much do something reloading related daily and sometimes prep for days paying attention to details