Using a Sinclair chamber length gauge

[Maxim0]

Hello, I purchased a Sinclair chamber length gage insert to establish the length to cut my brass but the reading I got is much higher then the information I’m finding on the internet.

I over Trimmed a case down to 1.9 then inserted the gauge and chambered the round. I chambered the round three times without any issues then measured the round which came out at 2.0545. From everything I read online it should be closer to 2.005 so I redid the process and came up with the same dimension. Attached is a picture with the round/gauge/caliper.

Am I doing something wrong or does my 700 .308 just have a really long chamber? Either way what should I trim My cases to?

According to the Sinclair instructions I should trim my cases to .01 under the measurement giving me a cut length of 2.0445. Which seems unreasonable considering my 5 times fired brass is only 2.0090.

I’m thinking of just trimming to 2.0100 once the brass stretches past that length at least.

Thanks for the help

 

[K.B.808]

As I was looking into using that exact gauge, did you ever get an answer for this? Any chance you're shooting a Rem700?

 

[Maxim0]

Yes I’m shooting a 700sa. No I never received an answer.
Discovered it was not a length issue. Am now 9 reloads in on my batch of lapua brass and still haven’t seen any reason to trim. Accuracy just keeping getting better.

I do Think it has to do with the Remington chambers

 

[Steel head]

My 260 chamber measures .02 more than any print 260 I’ve ever seen.
Yay!
No need to trim the necks for a while.