Rem 700 SPS 7mm Rem Mag Re-chamber to 7mm RUM

[williamsc31]

I got a Remington 700 SPS in 7mm rem mag and wanted to re-chamber to a 7mm RUM. What all would need to be done to do that?

[AZShooter]

Originally Posted by williamsc31

I got a Remington 700 SPS in 7mm rem mag and wanted to re-chamber to a 7mm RUM. What all would need to be done to do that?

While a 7 RUM reamer would clean up a 7 rem mag chamber the case won't fit past the feed rails of the remington action. In addition the magazine box is going to be short, you could help things with a Wyatt's mag box. Best approach if you want a Rem action for the 7 RUM is to get you hands on a Rem RUM action for your build.

[williamsc31]

So after I got it reamered and the Wyatt mag box what else would I have to do?

[AZShooter]

Gunsmith could use existing magazine/floorplate if it is a BDL and you could add the longer wyatt's mag box that has trianglar cutouts for this larger dia case or you could install a special detachable wyatt's magazine box with its own feed lips. Either way the feed rails must be widened.

You can call Wyatt's and talk to them. Here is link.

Magazine Boxes, Wyatt's Outdoor

[Max Heat]

Don't do it! The RUM is a high-pressure round, wear as the regular mag is not. And now you are going to cut the chamber out even thinner? I believe that the RUM rums at least 15,000psi higher pressure. I'd never trust the now thinner-walled lower grade steel to stand up to the 15 K increase in pressure. You need to get one that is already an ultra, just like I do. But you simply can't get the rem 84155 right now. I called them and was told production starts in April, available in May.

[.284]

The boltface is bigger on the rum too .532 to .534

[IdahoCTD]

The bolt face is the same between the two and the magazine box is the same length from the factory. The difference is the cutout's from the factory for the fatter case and a different follower. A Wyatt box is a good idea for the added length. You'll probably have to alter the feedrails to get it to feed the fatter cases properly.

Don't worry about the barrel thickness. The barrels are the same from the standard magnums to the RUM's.