i have a 300 win mag in rem 700 that i would like to rebarrel to 338 ultra.i noticed that the ultra case wont push down threw the feed rails. how much do you open them up and what would be a cost esimate. thanks

The RUM action rail width at the rear is about .562. It shouldn't require more than a couple of light swipes with a file followed by some fine emory cloth on each side to bring it there. Actually, .550 should work just fine. You will need to change magazine components for the Ultra case though. I probably wouldn't charge much more than $40.00 (Ooops, I didn't see your post John) $100.00 to open them. But then again I'm a "no longer" a 501C4 charity.

You open them enough to fit, duh!

You have to cut more than the rails, you also have to open it up to the rear, fit the larger magazine box and shorten the bolt stop. About $50 plus the mag box which is around $30.

EDIT: Let me say, you don't "have" to do it the way I said. I use a Wyatt's extended window magazine box which requires opening to the rear and shortening the bot stop. It's been pointed out to me that you don't "have" to do this if you only shoot 250 grain bullets and/or don't mind seating 300 grain bullets deeper than optimal.