300 wm custom freebore velocities

Antarcticchamp

Active Member
Joined
Jan 28, 2019
Messages
35
Location
Washington
For those who have 300 mag Chambers with increased freebore what kind of velocities are you seeing?
I think I've decided on a custom 300 wm barrel over a nosler or RUM and I'm curious how much I'll be leaving on the table.
 
With an A191 chamber, which is set up for a 215 Berger Hybrid, you can achieve over 3050fps in a 26" barrel, my 28", 30" and 32" run 3120fps, 3190fps and 3240fps respectively.
I can get 2980fps out of my 26" barreled Rem Sendero with RE25. But less than this with every other powder. This rifle is running a SAAMI chamber, with standard throat, it could be faster if I lengthened throat.

Cheers.
 
Does anyone know if the A191 chamber will work with Peterson long brass??
from what I gather the A191 chamber was designed to minimize case growth
 
I'm new to this. I'm rebuilding my 300WM (shot out factory barrel) to a remage with longer bottom metal and mags. I ordered an X-caliber carbon barrel with 1-9 twist in December. I'm wondering how much Freebore I need to put in the chamber. I'm thinking .01 or .015? What are you all experiencing?
 
I don't think it's that special, back in the day when we only had 240SMKs, we were running those at 2850 using H1000 from a 28 inch tube.

And we were shooting those out of slings for NRA style 3x1000 matches, talk about a beating.
 
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