improved 7mm rem mag

Discussion in 'Gunsmithing' started by maximini14, Jan 17, 2014.

  1. maximini14

    maximini14 New Member

    Jan 17, 2014
    I am interested in improving on the 7mm rem mag. My thought was to run a reamer thru my A-Bolt to yield greater case capacity by carrying belt diameter thru body. I was thinking why can't one have a chamber which is .532 from rim with minimum taper to shoulder. Push the shoulder forward using a 35 deg shoulder angle while maintaining the standard rim to neck length of 2.229 and maintain 2.500 case length. The 7mm RUMs and STWs would require a larger bolt face or magnum action to accomadate the 3.6 COL of these cartridges and a longer magazine box- I think! I have contacted RCBS and they do not have a die or reamer like I desire and there does not seem to be an existing cartridge that brass can be formed from! Any ideas?
  2. shortgrass

    shortgrass Well-Known Member

    Mar 31, 2010
    Yes! Do little more research. There's a'sticky' at the top of the page for "bolt face diameters".
  3. Garycrow

    Garycrow Well-Known Member

    Jan 30, 2011
    Ha! What you're describing is basically the 7mm LRM, there's a lot of discussion on here about it. It'd be much easier to build from that blueprint than to try and re-do all the work yourself to end up with essentially the same thing.
  4. valleyloader

    valleyloader Well-Known Member

    Nov 7, 2013
    There is a gunsmith in my area that re-chambers 7mm rem mags to 7mm stw (they are the same head diameter), a few years ago it seemed like he was doing a couple every week. He runs a reamer in the chamber until the correct headspace is achieved, as well as either lengthen the mag box or install a longer one depending on the model of the rifle. I witnessed this process on 2 different rifles, both were ruger model 77s (lengthened the mag box), everything always turned out good with these rifles and customers were always very satisfied. This would probably be the most inexpensive way to get more performance because dies and brass are already commercially available.