Opening up M700 feed rails?


Well-Known Member
Mar 29, 2005
Anchorage Alaska

I know that when you convert a standard bolt face long action M700 to a super magnum, like a R.U.M., that the bolt face needs to be enlarged, you need a ultra magnum magazine w/windows, and you need to open the feed rails.

Example; You are converting from a 7mm Mag to a 338 Ultra Magnum. You have to enlarge the bolt face, you should maybe install a sako extractor, and you order a brownell's extended magazine.

You also have to open the feed rails, right?

Can someone here post a pic of what needs opened, and where?

I know this may be a guarded "LRH Gunsmith" secret, but some like tinkering with their own stuff at times.

I guess I could measure one of my factory Remington Ultras to see what difference it has over the long action.

Anyone want to share? The proceedure is mentioned often on here.



Well-Known Member
Jan 12, 2005
63, The feed ramp is wider and lower on the RUM. You'll need a RUM follower for the magazine. The standard RUM magazine box with the windows will work fine unless you want to seat bullets close to the rifling. The rails are pretty close on the RUM and the 7mm rem. mag. but the gun I had converted fed much better with the rails modified. I don't know the exact dimensions but the great Smiths on LRH can tell you. The big question is do you want to risk ruining your action by doing it your self? Good luck----7mmrhb