What is the Casing Length for 308 National Match Chamber?

[Czoo]

What is the Casing Length for 308 National Match Chamber for trimming purposes? I'm assuming it is not the SAAMI spec of Max Length of 2.015in. Googling doesn't give hardly any info on a National Match Chamber Dimensions.

Update: It's the PTG Reamer
This is for PRS Matches not some plinking crap. Serious answers only.

 

[TheOfficeT-Rex]

Depends on the chamber reamer. I'm assuming you don't have a copy of the print.

If you have a hornady tool (or equal product), pop a 22LR case in the cartridge mouth instead of a bullet and measure.

Sinclair also makes a more elegant kit but this should get you close enough to swag a trim length.

 

[spife7980]

I would assume that its the exact same because who would go around fucking up case lengths and then calling it the same chamber. Its likely just a slightly tighter body diameter.
You should have gotten a reamer print before you had someone use an unknown reamer on your stuff.

We need actual reamer info to give you an actual answer. calling something a "national match" is the same as calling it "bobs bestest"... it gives no info.

 

[Skeptic1]

^^^^ exactly

 

[Rocketmandb]

calling something a "national match" is the same as calling it "bobs bestest"... it gives no info

I don't know, Bob makes some good shit...

Point Reyes Compost Co.

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www.prcompostco.com

 

[Czoo]

Update. The reamer is PTG

 

[B y r o n]

Maybe post #10 in this thread will help.

 

[spife7980]

Update. The reamer is PTG

Because ptg has only ever designed one reamer…

Just go by the saami trim length and you’ll be fine. It’s likely just a tighter diameter, akin to a small base die, to ensure no issues in an m1a.

 

[memilanuk]

Just trim it to the listed SAAMI minimum trim-to length for 308 Winchester - 2.005" - and find more important things to worry about.

 

[supercorndogs]

You are going to have to measure yourself to know.

 

[rmfield]

This is the way I do it when I don't have a chamber/reamer drawing:
https://bulletin.accurateshooter.com/2021/08/do-it-yourself-chamber-length-gauge/

 

[memilanuk]

You won't be able to shoot the difference between whatever you come up with, and SAAMI trim-to length.

 

[Haney]

You won't be able to shoot the difference between whatever you come up with, and SAAMI trim-to length.

But....why trim brass when you don't need to ? Knowing one's chamber dimensions goes way beyond "shooting the difference" . One example is preventing a place for a carbon ring to form . Short brass gives it a great start .

 

[memilanuk]

Trim your brass every firing, and clean the barrel on the regular, and neither of those are an issue.

 

[memilanuk]

And FWIW, if you're getting a carbon ring in a 308 you're doing something stupidly wrong.

 

[Haney]

Trim your brass every firing, and clean the barrel on the regular, and neither of those are an issue.

And FWIW, if you're getting a carbon ring in a 308 you're doing something stupidly wrong.

I can tell you just don't understand . Can't teach those not willing to learn I guess .

 

[Rover31]

I can tell you just don't understand . Can't teach those not willing to learn I guess .

You telling him that is friking hilarious…
I want to hear more!

 

[Dolomite]

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