7mm mag to 7 rum?

buckmaster! · 10-11-2009, 04:11 AM

New to the savage swap game (obviously =) , but I have been reading from the wealth of knowledge here for quite a while.

Sorry if this is a dumb question, but no harm in asking.. (except my pride) ::)

I have a 110 7 mag, small shank, factory barrel & am wanting to change it to a 7 rum..
Would I be able to use this same barrel & just change the headspaceto fit the larger case?
Mag box isn't an issue, I would probably just keep it as a single shot as I'm using long Berger VLD's..

Thanks for all your help!

**efm77** · 10-11-2009, 07:23 AM

Changing the headspace has nothing to do with it, they are two completely different cartridges. You would have to either have your chamber re-bored or buy another barrel. The RUM shell is longer and larger diameter than the belted mag shell. Most barrel makers will chamber one in a small shank barrel although there has been quite a bit of discussion as to whether it's safe or not. I've never heard of any barrels splitting though.

**BobT** · 10-11-2009, 10:18 AM

Welcome to the forum!

I'm pretty sure your factory barrel is only 24" long to begin with so I don't think rechambering to the 7mm RUM would gain you too much. The big cases need longer barrels and slow burning powders to reach their full potential. I would not personally consider a barrel less than 26" long and more likely would go with 28" or 30" . As far as the small shank action goes I think if I built a RUM on one I would probably not use the barrel nut and go with a larger diameter shank in front of the recoil lug but then again the barrel nut is one reason I like the Savage action so much to begin with!

Bob

**HRstretch** · 10-11-2009, 07:41 PM

You need a new 26" to 28" barrel and a small shank will be fine.

sinman · 10-11-2009, 08:39 PM

Yep defiantly a longer barrel and like said before the small shank is perfectly fine.

buckmaster! · 10-11-2009, 08:55 PM

"no harm in asking.. (except my pride).." Ouchy lol :P

But seriously thanks for setting me straight fellas. I actually may have found a 116 300 rum pre accu locally for around $325. Sounds like a pretty good deal if I can get my hands on it.
In the mean time I'll keep lurking & learning.

Thanks again!
I Love this place

**efm77** · 10-12-2009, 08:10 AM

That does sound like a good deal, good luck with that. I'm no metalurgist but what I think about when using a conventional shouldered barrel is, yes it's thicker where the shoulder starts and that's a good point. But, what about the portion under the recoil lug? That's still the small shank exposed from the receiver. Now granted, it's a small area but I doubt the recoil lug would be enough to prevent a barrel bulge. Although I've never heard of it happening. Remington uses roughly the same shank diameter with larger/deeper threads and they haven't had any issues. The shoulder portion is thicker but there's still an exposed portion of the small shank outside of the receiver and I would think if it were going to let go, that's where it would do it. Again, as stated before though there's plenty of them out there and I haven't heard of any problems. I do feel better with the large shank size though since there's a little more metal around the chamber even what's under the recoil lug. And it's really not that much smaller than the shouldered portion of a Remington barrel.