What is case trim length?
Likewise, how important is case trim length?
Case length does not affect powder capacity, at least not that it can be "remedied/restored" by trimming. Case neck holds bullet, not powder. The only reason to trim is to assure that brass has not moved into neck pushing neck length beyond the chamber dimension.
6.5mm Creedmoor | |
---|---|
Case length | 1.920 in (48.8 mm) |
Overall length | 2.825 in (71.8 mm) |
Case capacity | 52.5 gr H2O (3.40 cm3) |
Rifling twist | 1-8" (203 mm) |
Just so, do you trim cases before or after resizing?
The main reason for trimming is so your case isn't too long for your chamber. There is "1" exception. That is if you're using the X-Dies. In that case you trim once before sizing and then you never trim again.
The Max case length for the 223 is 1.760 inches. The trim to length is 1.750 inches. If you actually trimmed your brass to 1.45-1.50 you would have no neck left. The junction between the shoulder and the neck measures 1.557 inches.