03-06-2014, 03:39 AM
(This post was last modified: 03-06-2014, 04:43 AM by bigbear_98.)
Everyone is posting about coal and chamber length. I was doing some experimenting the other day with my chamber using the hornady gauge. I measured with a sinclair 30 degree bump gauge
The case that hornady sends out is 1.514 oal. 1.128 from base to shoulder.
My once fired brass (9pc out of 10) is 1.510 oal, but 1.138 base to shoulder. Since the shoulder is what stops the case in the chamber, the lock and load case would be .01" short of my breech face. Which means the bullet will be .01" out of the lans when chambered if I go by this tools measurement.
Now I'm not planning on jamming my reloads into the lans, and I know I will be bumping the once fired brass back when I resize, but I was interested to see such a large difference in my once fired brass and the tools brass.
What do yall think about it? Is everyone accounting for this difference when measuring?
This also leads me to ask, how much do you bump the shoulder back on a semi auto? On my bolt gun I only bump it .003 when I resize it and that is after 5 reloads on a batch.
![[Image: 65Grendel.png]](http://accurateshooter.net/pix/65Grendel.png)
The case that hornady sends out is 1.514 oal. 1.128 from base to shoulder.
My once fired brass (9pc out of 10) is 1.510 oal, but 1.138 base to shoulder. Since the shoulder is what stops the case in the chamber, the lock and load case would be .01" short of my breech face. Which means the bullet will be .01" out of the lans when chambered if I go by this tools measurement.
Now I'm not planning on jamming my reloads into the lans, and I know I will be bumping the once fired brass back when I resize, but I was interested to see such a large difference in my once fired brass and the tools brass.
What do yall think about it? Is everyone accounting for this difference when measuring?
This also leads me to ask, how much do you bump the shoulder back on a semi auto? On my bolt gun I only bump it .003 when I resize it and that is after 5 reloads on a batch.