Brass Trim Length

[SteveBurton]

I got done cleaning my 6.5 PRC and just out of curiosity chambered a prepped piece of brass and ran my borescope down the barrel. The brass is trimmed to 2.220" length. Seems like a lot of space between the neck and throat of the barrel. I do have the Sinclair chamber length gauges but was wondering what others do to trim their brass to their chambers? Just run SAMMI trim length or something tighter like 0.0010" clearance? I'm guessing longer necks help eliminate some of the carbon ring? TIA

 

[Carlos88]

I use the SAAMI number and have never had an issue. Longer than your chamber dimensions can cause serious problems.

 

[MagnumManiac]

I use SAAMI MAX as my trim to length in my normal hunting rifles, but run my brass to .005" of chamber length and trim .010" from that in my comp/precision rifles.
All that room creates carbon rings in long strings of fire without cleaning for 200 odd rounds.

Cheers.

 

[AZShooter]

Another use for the bore scope! Hadn't thought of that one. Brilliant!

I compare reamer specs to brass length. With the few that are not made by my reamers I use the chamber plugs which I made myself.

I now have an easier way to check for brass fit!

For those with a lathe here is a link for the dimensions on the plugs. Thanks Varmint Al

Varmint Al's Mini Lathe Page

 

[captrjc]

I use the Sinclair chamber gauges and trim .010 short of chamber if the cases move that far. Honestly I do it for two reasons.. first, I hate trimming. Second, I'm of the belief the chamber stays cleaner (no carbon ring).
I don't do it on semi autos.
It has been my experience that most sammi trim length specs are much smaller than the actual chamber. I haven't seen any more accuracy or anything negative. I really believe that neck tension is king and obviously that tension changes with length but I guess I'm just not that good of a shot to see a difference.
I am curious if anyone here knows of a reason not to do it because I'm not a stranger to doing stupid stuff.

 

[Pdyson]

I trim everything every time I reload. Primarily so my reloads are all consistent. This is a great idea and I can't wait to scope my chambers.

 

[AZShooter]

Got to thinking about using my hawkeye to see the brass and end of chamber. I realized that I don't have a single rifle with a barrel short enough to view the chamber from the muzzle end.

I suppose I could drill out the base of a case to view from opposite end. Then the case could be used as for comparison with brass that has been sized multiple times.

Then again, I may never drill out any cases as I already have the end of chamber measurements for all my barrels.

 

[Seabeeken]

I take my long brass and chamber it as you did and bore scope to get it very close to or at the edge of the chamber. If it is at the end of the chamber I trim .005" and go with it. It helps keep carbon up in an area where it is easier to deal with and it makes for a better more complete fit. After all, we are all about making our ammo for OUR rifles, so why would you want a perfect fit everywhere except length. I also believe it helps make a better flow of the hot gases into the throat. Just my .02