Anyone not trim?

[jelrod1]

I'm shooting a .308 load that's on its 5th loading that I've yet to trim. Load is Lapua brass, 44.5 Varget, Berger 175 OTM, Fed match primer. I FL size every time and set the shoulder back to a once fired state (moving around .001). The cases from new have grown only .004-.005 total. Using a redding body die in combination with a Lee collet die for the sizing. I know this chamber is tight, but does anyone else not trim or is this an anamoly?

 

[Luke_NL]

Why would you not trim? Thing is, the trimming doesn't so much have to do with the chamber dimensions as it does with uniformity of your cases. They will not all 'grow' at the same rate, so you will have some that are longer than others. This will influence the amount of resistance the bullets encounter before release into the lands, which should in turn have an effect on the vertical spread. As long as you stay within saami specs I guess you're not doing anything outrageous, but unless you're talking hundreds of cases I don't see the point of not trimming to keep your groups tight(er). Then again, if you were to test trimmed v. not trimmed and not be able to see the difference, then by all means omit trimming ;D

 

[BoydAllen]

Some of this is about your accuracy goals. If they are being reliably met, then as long as your brass is short enough to be safe, you are good to go. Back in the day, I used to think that trimming to a length that was a little closer to the book max had some merit, I have changed my mind. I have a chamber and bushing FL die situation for one rifle that shows almost no case growth, so I am familiar with your situation. I try to trim every so often just to square case mouths, but I wait till there is enough growth to cut to fresh material when I do. I don't want to cut half way across, or have to shorten below my trim length to clean up. One of the faster tools to get through this chore with is one of the Possum Hollow trimmers, mounted in one of the drill adapters for one of the chamfer/deburring tools. The tools are the same diameter. With this you can hold the drill in one hand and handle cases with the other. Give the case as twist as you finish.

 

[jelrod1]

Thanks guys. I'm glad you are familiar with this situation Boyd. It's not that I'm trying to get out of anything, just not seen the need to do it yet and wondered if other people see this or not. This is the only rifle/die combo this has happened yet for me also. So far there have been no accuracy issues. The things have grown amazingly similar. Other rifles in the past I would trim every other time or so.

 

[M14AMU]

Not trim? Oh...yes sir! I see lots of guys/gals building a shed over their belt buckles!!

 

[Turbulent Turtle]

I have a similar load and I only trim my Lapua cases every fifth load or so.

My belief is that using a bushing die with not expander ball reduces the case stretching.

 

[BoydAllen]

The main factor in whether cases grow or not is how closely the FL die matches the chamber. If you measure the case at its largest point above the extractor groove, and at the shoulder, before and after sizing (of a fired case) , and note the amount of shoulder bump that your die setting produces you will have most all of the information that you need to evaluate this situation for your rifle and die. The die that I referred to in an earlier post does not reduce the shoulder, sizes the base .0005 and I set the die for a bump of a maximum of .001, usually less. When I fire form the brass, it gets shorter. I trim to 1.490 to make them uniform and square, and my reamer's drawing lists a maximum case length of 1.515. I only trim to uniform and square. Ammo from this die and a good seater is very straight and is very accurate if the load is right.