223 Case Length Trimming

[tom1]

I have a batch of 223 cases that are getting a bit long , measuring over 1.765" . These are Lapua cases , not the Lapua Match cases if that makes any difference. Interestingly these cases are heavier than my other batches of Lapua Match cases , weighing approx 103gr . The Lapua Match cases weigh about 95 -96 gr.
Do I trim back to 1.760" or take a bit more off ?
These will be fired in an Omark
I have recently ordered a Body die to use with my Lee Collet die , previously using a Redding FLS which probably accounts for case lengthening .
Thanks for any advice.
Brad Probert.

[tachyon]

The SAAMI spec for 223 case length is 1.730" to 1.760"

1.760" is the maximum length so you do need to trim or your chamber throat will start to act like a crimping die and potentially push the pressures up.

Generally people would take 10 thou from the max length ie trim to 1.750"

Despite the fact that 1.730" is the technical minimum length 1.740" would be a "working minimum" so you could trim them shorter than the suggested 1.750" if desired but if you have the projectile only partly seated in the neck the more you trim, the less neck there is to hold onto it.

SAAMI-223.png

[Southern700]

I agree with tthe points made by tachyon. I personally trim to 1.750.
Whatever length you choose, consistency is (obviously) the key.

[tom1]

Thanks for the replies, I have trimmed the cases to 1.750"
Cheers .Brad Probert