Is the current production Model 70 action of suitable length for conversion to the long Ultra Mag family of cases? Would bolt face and feed rail modifications be necessary? Thanks for all responses.

My 375 RUM is based on the M70 Stainless Classic in 375 H&H. Barrel was reamed to 375 RUM. It even holds 3 in the existing mag but is a tight squeeze. And it feeds without much more than modification to the magazine spring.

I think you will find that Win offered the 300 Rum as a factory calibre & the other RUMS as custom shop specials.

I am assuming you are talking of full length Ultra. If you get magnum bolt face & H&H length then no opening up of ejection port nor of bolt face. Getting it to feed, well that is another matter. My gunsmith managed to get it to feed (not like an H&H - but OK) without feed rail work. That may not be acceptable to you, then more work may be necessary.

Regards
JohnT

I don't have a RUM, but I just picked up a 270 WSM. The magazine geometry is all wrong. The shoulder pinches in the box. If the rear end of the cartridges are pushed down(while in the box) they stay down and the bolt fails to pick up the second round down.

Jim Dubell your phone is ringing.

Well, you're asking about length, right?
The RUM is nominally the same length as the H&H, or the 300 Weatherby, or the 7mm STW, etc.
Plenty long for all of those. It's thicker, so feeding issues will have to be addressed.

Up until last year, Winchester made the M70 Classic SS in 300 RUM. According to their web site, it is still available from the custom shop. It's built on the Express action, same one used for 375H&H, 416 Rem and 7mmSTW. Same overall length as the long action, but with the loading port opened up in the rear and bolt stop shortened.

For those using the RUM case, there is a magazine box and follower specically for the 300 RUM. Brownells caries them or you can get them directly from Winchester parts. About $30 for the mag box, not sure on the cost of the follower.

I've got a Model 70 action that was originally a .300 Weatherby. I'm able to get two .375 Ultras in the mag, and it will CRF both rounds. I'm going to put a .300 Ultra mag box and follower in it to see if it will hold and feed 3 rounds. I have plans to have it made into a .338 Ultra if all goes well. I too am interested in having more people chime in who have done the conversion.

The standard long action (30-06, 300 Win Mag, etc) Model 70 is the same action that houses the 375 length cartridges but the loading/ejection port has been opened and the bolt stop shortened.

Chuck

My .404 Jeff. is made on a M70 .300RUM action. It appears to be the same as the .458 that I used to have.

You aren't looking at 70 classics then.

Chuck

ASS_CLOWN

I have 8 M70 Classics in my safe, all actions unmodified. Four of them have the "opened up" loading/ejection port (7mm STW, 375H&H, 416 Rem, and 470 Capstick-originally a 416). The rear bridge is about 1/4" shorter on these Express actions than on the standard long actions. You can also spot the difference between these actions by looking at the rear scope base mounting holes. On the long action, the hole spacing is .860 and on the express action the hole spacing is .330.
The other four M70 Classics with the standard long action are 7mm Rem Mag, 300 Win Mag, 338 Win Mag, and 30-06.

The Model 70 long action that houses the 375, 300WBY, 7STW, 416 Rem are the exact same action that USRAC houses the 30-06, 270, 7mm rem, 300 WM, 338WM in. The difference comes in the modifications to the action. The actions that are used for the longer cartridges have had the ejection port opened to the rear, removing one of the holes, or the location for one, in the rear bridge. The reason the hole spacing is different. A different box and bolt stop are also employed with the different cartridges. So besides those modifications, the actions are the same.

Chuck