I am considering having a 7mm RUM rebarreled to 404 Jeffrey. I'd appreciate any thoughts on this conversion. I know it is not controlled round feeding and some would look down on using a Remington action but cost is a factor and I already have the 7mm. Thanks!

Yes, you can rebarrel your existing action to the 404Jeffrey without any alterations to the bolt or magazine. The rim of the 404 is .003" larger diameter than the RUM but that is considered insignificant. If that is what you need and want you are good to go with a new barrel.

I just measured both and get a rim diameter difference of almost .012".

the head dia. of the UM measures .546" the head dia. of the .404 measures .543".

First of all the rim dia. difference shouldn't be much of a problem. The extraction groove diameter difference might require a little looking into. the UM exraction groove dia. measures .464" on a Bell .404 it measures .482", on Norma .404 it measures.484". It has been found that the groove dia on the Bell .404 cases have varied enough from lot to lot causeing me trouble.
Non of this is beyond a qualified Gun Smith's ability to solve.

One of my wildcats that uses .404 cases also now uses UM cases. It did require a little chamber lapping , but not much. .375UM cases can be had cheaper than .404 cases. Perhaps you would like to consider that option, just a thought. roger

quote:

I just measured both and get a rim diameter difference of almost .012".

That is the difference I see between 300 RUM factory ammo and brand new Norma 404 brass.

Thanks for the replies. Do any of you have an opinion on barrel length and twist rate?

I am assuming I'd use 400 grain bullets but am open to suggestions. Personally I would like to stay away from a barrel over 24" unless there is some compelling reason not to.