.308 brass trimming based on chamber length?

[Leaddog]

I've always trimmed my brass to 2.005, but some have said it is better to measure your chamber and trim closer to your chamber's actual length. Helps with erosion and gives better consistency, they say. I don't know.

With a measured chamber, how far do you set back your trimmed brass?

 

[leatherman]

Re: .308 brass trimming based on chamber length?

Sinclair makes a great little tool for what your wanting, I dont have my catalog handy but you can look them up online. There just plugs that go into a fired round that has has been trimmed below book stnadards IE 2.005, you then insert the plug into your case and gently close your bolt. The plug will stop at the end of the thoat, extract the round and take you measurement. That gives you you chamber trim length.

Vague I know, but hope it helps.

 

[427Cobra]

Re: .308 brass trimming based on chamber length?

I trim back .010, takes a couple cycles to get there, on a new chamber it's easy to do, on a chamber with 2k-3k rounds it's pretty long if you have been trimming back to 2.005, the Sinclair instructions say .024

 

[Leaddog]

Re: .308 brass trimming based on chamber length?

Excellent info guys. Thanks.

 

[vman]

Re: .308 brass trimming based on chamber length?

http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage

 

[littlerascal56]

Re: .308 brass trimming based on chamber length?

My Rem M700 measures 2.020. I trim to 2.010 and shoot until it gets to about 2.017 and then it's time to re-trim.

I like to keep it longer...seems to give better support and neck tension to the bullets, which I load to 2.850 OAL for my AICS mag.

 

[Rover31]

Re: .308 brass trimming based on chamber length?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage </div></div>

great tool, super cheap! you should own one in a couple of calibers and then your buddies should buy a couple of other calibers... then share!

 

[Hummer]

Re: .308 brass trimming based on chamber length?

there is another way I use. When I rebarrel I take the muzzle end I cut off and lay it aside. It is about an inch long.

After I finish the barrel I chuck up the short piece and run the same chambering reamer in leaving it about 1/8" shy of having the neck area of the reamer come through. Then turn the piece around and face it off till you have about .025" shelf left to show you where the end of the chamber is.

Insert cases into this gage and you can tell exactly where your neck is in relation to the end of the chamber.

Larry Moore told me years ago if you are going to be shooting a long time you need to have your own reamer to min dimensions so you don't overwork brass and brass can interchange between rifles of same caliber without massive reworking.