Trim length

3

338lm

Guest
I would like the Benchrest shooter's opinion's on the following questions:

1) How much space is sufficient for brass expansion between the end face of the case neck and the face of the chamber before you start trimming your brass?

2) Do you want as much case neck length that is safely possible? Or is the opposite the objective? I understand that this question is probably caliber specific, and also depends on whether a person is neck sizing with a bushing, or sizing the complete neck length.
 
Length depends on how well you monitor your cases. I watch mine all the time and trim to .010 under
max. when they are within .004 or .005 under max.
 
I think it depends mainly on how much the case grows in one shot. As long as you're below the OAL measurement of the chamber you're OK. If a case is going to be longer than the chamber, next shot, you need to trim it a little. I want to believe if a fired case (a case when fired) completely filled the chamber it would be better than all else. What I do believe is that's all but impossible and closely matched cases that are somewhat less than the chamber length are all that can be hoped for. How close you get doesn't matter so long as you don't go over.....

I don't think any standard exists for "too short"...could be wrong. In fact, I have a 222-1/2 example that pushes that thought significantly.

Said differently.....Often, there's a big difference in the length of a loaded case and the same case fired. The fired case is where trimming comes into play - just to make sure you understand...if you don't already. The entire object is to have a fired case equal to or less than the chamber.
 
Last edited:
338lm said:
I would like the Benchrest shooter's opinion's on the following questions:

1) How much space is sufficient for brass expansion between the end face of the case neck and the face of the chamber before you start trimming your brass?

2) Do you want as much case neck length that is safely possible? Or is the opposite the objective? I understand that this question is probably caliber specific, and also depends on whether a person is neck sizing with a bushing, or sizing the complete neck length.
Click to expand...

.010" [10/1,000 thds] for safety, and another .010" for growth regardless of caliber. F/L sizing all the time, with a F/L Bushing Die, eliminates headaches. Bushings should size about 70% of the neck. :)
 
Cases can only "grow in length" by the amount of headspace present in your setup. In other words, if you have .002 of slop in your chamber, the case will generally stretch just less than .002 at the base to make up for that slop. Minimize or eliminate headspace and you'll minimize or even eliminate the growth.
 
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