Question for Real M-70 Smith's

[INTJ]

Looking at the action, Someone has opened up the rear of the action to accommodate for a long cartridge, It's possible this action was not originally for Ultra mag.

Like I said in my original post, I opened up the action myself for the 3.825" Wyatt's box. This is indeed a RUM action as evidenced by the cutout in the left rail.

I have had great success doing this on standard magnum M-70 actions and getting them to feed reliably. I had originally thought an M-70 RUM action would be an even better choice to modify, but it's not.

I even discussed this with Shawn Carlock a while back when he came to my shop--as he does from time-to-time. The first thing he mentioned was the issue with the cutout in the left rail when opening up the magazine well.

That cutout in the left rail is fine with a non-modified RUM action. The shoulder of a RUM case is forward or nearly forward of the cutout so the left side case doesn't pop up. However, extend the magazine opening back .230" and the use a 28 Nosler case, and you get the issue I show in the pictures.

 

[Sniperhandle]

Gotcha, The info In D'arcy Echols blog is still very informative when getting bolt guns to feed, You may pickup some tidbits that will help you in the future, One thing that I remember I learned was how to fit crf extractors using an indicator.

Like I said in my original post, I opened up the action myself for the 3.825" Wyatt's box. This is indeed a RUM action as evidenced by the cutout in the left rail.

I have had great success doing this on standard magnum M-70 actions and getting them to feed reliably. I had originally thought an M-70 RUM action would be an even better choice to modify, but it's not.

I even discussed this with Shawn Carlock a while back when he came to my shop--as he does from time-to-time. The first thing he mentioned was the issue with the cutout in the left rail when opening up the magazine well.

That cutout in the left rail is fine with a non-modified RUM action. The shoulder of a RUM case is forward or nearly forward of the cutout so the left side case doesn't pop up. However, extend the magazine opening back .230" and the use a 28 Nosler case, and you get the issue I show in the pictures.

 

[shortgrass]

Like I said in my original post, I opened up the action myself for the 3.825" Wyatt's box. This is indeed a RUM action as evidenced by the cutout in the left rail.

I have had great success doing this on standard magnum M-70 actions and getting them to feed reliably. I had originally thought an M-70 RUM action would be an even better choice to modify, but it's not.

I even discussed this with Shawn Carlock a while back when he came to my shop--as he does from time-to-time. The first thing he mentioned was the issue with the cutout in the left rail when opening up the magazine well.

That cutout in the left rail is fine with a non-modified RUM action. The shoulder of a RUM case is forward or nearly forward of the cutout so the left side case doesn't pop up. However, extend the magazine opening back .230" and the use a 28 Nosler case, and you get the issue I show in the pictures.

It looks like Mr Carlock knew what he was taking about!

 

[AlNyhus]

So....what did you do for a fix? -Al

 

[INTJ]

So....what did you do for a fix? -Al

I haven't tried anything yet. I'll post back here when I do

 

[Catfur]

I haven't tried anything yet. I'll post back here when I do

Any updates on this? I have a Model 70 I'm looking to get the mag box extended or replaced on...

 

[INTJ]

The mag box extension is easy and works well. The issue is extending a magazine on a RUM action. I haven't done any more with my project as of yet.