Hello everybody, this is my first posting on this forum.
Got some question for you:
What needs to be done to a rem700 left hand action in 338 win to be converted to 338 rum.

Do I need a new:
magasine box?
follower?
anything done to the action?

Tried some cartridges and the one feed from the left side of the magasine jumps up to early! The one feed from the right side feeds ok.
Thankful for any help.

Just rebarrel it to 340 Weatherby. It'll feed like the action was made for it and it's pretty well the equal of the Rum,..within 100 fps anyway. You could also rechamber your factory barrel.

Just click on the "Find" box above and do a search. This was asked a couple of times recently.

Not a big deal, a factory RUM mag box will get you close.

I put together a 300 RUM and a 7MM RUM. Still working on my 375 RUM. All I had to do was open the feed ramp so that it was as wide as the front of the feed rails. The RUM case's shoulder would hit the feed ramp before it had a chance to nose into the chamber and jumped out all the time. The wide feed ramp allowed the shoulder to follow into the chamber with out lifting too soon. Don't change the ramp in any other direction except making it wider not longer. Lenghtening it would weaken the lug area of the action. Also had to replace the mag box to accept 3 in the box. The replacement box has the window cutout in it to allow the shoulder to spread a little more. You can almost get three in the old box but just not quite. I used take off stl. barrels and had to set the head space. The 375 take off barrel is an H&H chamber but will clean up real nice when it is done. These are not fancy guns just bread and butter hunting guns. The 300 and the 7MM both feed real smooth and shoot right around 1 inch three shot groups. A poor man's RUM collection from antalope to brown bear.