7mm08 Chamber measurements

[powderBurnz]

I'm having an action rebarreled to 7mm08. I'm wondering what I need to tell the smith as far as dimensions for the chamber. I want to seat 162amaxs, Berger vlds as long as alpha type2 mags will allow. Neck and throat angle should just be normal 708 dimensions no? But what about free bore?

 

[ShootDots]

I'm having an action rebarreled to 7mm08. I'm wondering what I need to tell the smith as far as dimensions for the chamber. I want to seat 162amaxs, Berger vlds as long as alpha type2 mags will allow. Neck and throat angle should just be normal 708 dimensions no? But what about free bore?

Unless someone knows the exact length of your magazine well, you will have to measure it or have the 'smith measure it and then seat the bullet you want in a case so it works well in the magazine. Then take the base to ogive measurement of a half dozen dummy rounds. Then you will be able to tell what freebore you will need. A couple of things should be considered. Unless you have a VERY long magazine well, you will not be able to seat those VLD's into the lands on a "normal length" freebore, for those bullets. MOST VLD's love to be seated into the lands. However, Berger does have a system where you can get excellent accuracy seating the VLD's W-A-Y off the lands. That could pose a problem too as you may have to seat the bearing surface BELOW the neck shoulder junction where doughnuts tend to develop. Most, if not all, of those "problems", could be overcome with proper measurements and the proper freebore. That will take diligent measurements and a good talk with someone like Dave Kiff from Pacific Tool and Gauge, who is extremely knowledgeable of reamers and freebore, as that is his profession.

 

[XTR]

For what it is worth.

My 7-08 reamer from PT&G was spec'd for 162s has a .188 freebore; however, it is a hunting rifle that, and as it turns out, I never shot 162s in it.


I decided to go with 140s and never worked up a 162 load. I don't know how long they would be to the lands, and I don't have any here to check. I've looked in my logbook for that rifle and I never recorded the base to ogive with the 162s either.

 

[Toolbreaker]

I can't give you an exact number for the freebore you need, but I can give you some dimensions from my notes when I was using the Amax's in my 7mm-08:

1) Brass trim length 2.025"
2) COAL seated to lands 2.975"
3) .284 Amax length 1.410"

These numbers place a loaded to jam round with .460" of the bearing surface and boat tail in the cartridge case. The SAAMI 7mm-08 uses a .274" long neck when trimmed to 2.025", so this would have placed .186" of the bullet below the neck/shoulder junction. I Googled the Alpha Type 2 mag, and it shows an inside length of 2.965". I'm betting that the .188" freebore that XTR stated should be darn close, giving you a little room for bullet jump.

 

[powderBurnz]

Thanks gents, much appreciated.