Help With Overall Case Length

[cookietheswede]

I thought I would try to add one more precision step to my reloading and get a chamber length gauge (Sinclair G308). My problem is I am getting a long reading. On my .308 cartage I am getting:

2.0455
2.0465
2.0455
2.0450
2.0455
2.0460

I have trimmed the case back all most all the way to the neck Single feeding it. And closing the bolt slowly and am not felling any "unusual" resistance.

Gauge measures .3345 round.

Thanks for any help.

 

[mattj]

If you have a factory rifle, your readings may be correct... (not uncommon for factory rifles to have ridiculously long chambers -- one of the many reasons a custom tube can make a big difference).

 

[mattj]

(whoops, my bad, was thinking of the wrong tool)

 

[427Cobra]

Well it seems that 2.005 is too short, but on 308 it maybe ok, once you start shooting overbores trimming back to book minimum is a bad idea, causes the chamber wear out faster, I also doubt that its possible to shoot the difference in trim lengths unless your shooting a tight neck BR round, so let that brass grow to .020 from the end of the chamber, then start trimming, when you switch to a overbore .010 from the end.

 

[justinbaker]

my factory 700 is the same, measures at 2.045

at least we dont have to trim very often =)

 

[cookietheswede]

Sorry should have posted the rifle. It is a DTA SRS, 22' 308.

Good to hear it isn't uncommon. First time with this measurement. Can a cartridge grow too long?

 

[Sniper260]

The reloading techniques at the top of this reloading forum explains this.

 

[milo 2.0]

Lapua manual says to trim to "2.008", so you're ".003 under that, you're fine. If you had an RCBS x-die, directions would have you trim to "1.998". Load em up and have fun.

 

[ChrisGarrett]

SAAMI max CASE length is 2.015". 'Trim To Length' is usually listed as 2.005", except for Lapua. I've never used that tool before and I don't know what reamers DTA uses, but you should be able to let those necks grow a little bit.

Take a sized case with a long neck, so something like 2.010", 2.015", etc. and measure the case mouth carefully, for diameter and color it with a dry erase marker, or Sharpie and gently chamber the case and extract it. See if you get any movement in the 'mouth diameter', alerting you to any 'pinching'.

Chris