I want to put together a 404 Jeff, but I don't have the money right now to have a builder put one together the way I would like. My plan was to start with an off the shelf rifle, new or used and rebarrel it and add things as time goes by. I have seen a few on this site that people have built off 300 RUM actions, and was wondering if that is the easiest route to take. I would assume so since the ultra mags are bassed of the jeff case. Also does it matter if the gun is 300 or 338 RUM. Any advice anyone could give me on the subject would be greatly appricated.

Can't say for sure about the 338, but I had one made from a 300 RUM, and it was pretty much a rebarrel and add iron sights.

the 338 RUM is 2.65" Vs 2.85" for the 300. Knowing Remington, the box is just a teensy bit different (shorter?). You might consider using a 98 Mauser instead. Down the road, when you get your custom built; the 98 will have twice the resale of a 700.

JMHO,

Rich

Box is the same on the Remington. Either will work.

thanks, that's good to know.

Rich

adding a 375 mag box.

Rich

find a windowed or rum box and follower ... might have to adjust the ejection ... and have a blast

Open the top of the action to the rear.

Drill and tap new scope mount hole on rear bridge.

Re-do the "scallop" on the inside of the rear bridge.

Open the feed rails at the very rear.

Do the little scallop at the rear top of the mag area.

Replace or shorten the bolt stop and ejector.

Open the bolt face about .005" just to give the case a bit more room. Not necessary in all cases, but if you are there squaring the bolt face...

Use an Ultramag mag box, 375H&H follower. Mauser mag spring.

Tweak the feed rails to get it to feed. Usually feeds pointed bullets as is, round and especially flat noses...not so much.

Can easily be done in a day. The last action I opened up I took photos, just haven't got them loaded onto a page yet.

Oh, and the RUM box and H&H follower are still available through Winchester Parts.

I would just buy a CZ in 416 rigby and save yourself the trouble. When you can afford it get a good custom rifle made. You dont want a home made unreliable big bore rifle. trust me.

A CZ Rigby can be had new, for under a thousand dollars.

Rich

I built mine from a 300RUM. Had it rebarreled, used the existing stock w/ some tweeks & went hunting. It needed a bit of tweeking on the follower & rails to get 100% feeding, but shoots great, looks pretty good for the factory stock. At some point I may have a custom stock done, maybe replace the bottome metal w/ a drop box from Blackburn, but I love it the way it is.