WSM/ SAUM on a Rem. Mag Action


Well-Known Member
Jun 12, 2001
Palmer, Alaska
I will try to feed some through my 700.

Dave, my smith hates the Remington for feeding the Ultra mags though. He said the magazine box is too narrow to start with and they ignore the formula to figure the rail width, length and shape. They just did what they could to "make" it feed.

His suggestion I know would be to use a Winchester M70 as was his when I bought my 300 Ultra too. His opinion is you cannot count on them 100% to feed the fat case designs. They jump out of the action etc. I have'nt even fed any out of the mag yet with mine, only top fed at the bench so far.
Thanks Brent. The cartridge has to feed from the magazine or the project is not worth doing. This is to be a long range "venison getter."
Has anyone built any of the WSMs or SAUMs on a full length Rem Mag action? My brother is considering a 6.5/300 WSM or SAUM and is wondering if he is going to run into feeding problems. Do these fatter cases work without modifications to the rails or do things have to be opened up to accommodate these cases?
Grab a Savage 11F from Wholesale sports for $550 and have fun. Sounds like the best bang for the buck in this cal. at this time.

Whatever the calibre is in your action right now, that is the case family I would stick with. The follower, mag, and feed rails are already set up. Adjusting to different cases can be a royal pain especially if you get the feed rails wrong. Single shot forever.

Good luck...

I was just looking at the rail in my 300RUM and my 300WM, both Rem700's and they look identical. I havn't measured them but I'd think they would be different. I'll see how that 300WSM feed out of the 300RUM tomarrow. My father will have his 300WSM at the range then.

Anyone see the new 223 and 243WSSM's yet? Yep, supershort mags.
Yes, getting those fat-assed cases to feed can be a bitch! I recently had my 300 Win Mag A-Bolt rechambered to 300 RUM.

I thought all I had to do was buy a 300 RUM magazine and pop it in. WRONG! The magazine wouldn't even fit into the rifle. It was too fat and too tall (at least Browning made the mag big enough).

I had to trim a bunch of material from the mag to even get the floorplate to close. Of course it still wouldn't feed--AT ALL!

I had to open the opening at the bottom of the action slightly to make these fat things even fit through. Then I had to "round off" the feed ramp leading into the chamber as well as the material that backs the locking lugs at the rear because this fat cartridge simply wouln't fit through the opening provided....

So, it now feeds slick as snot. But it wasn't easy. If you hear from my next of kin that I've blown my head off, then you know not to try what I did at home....

Anyway, it can be done but it isn't easy. Your best bet is to buy a rifle intended for one of these things or have a really good gunsmith build you one.

As a Mechanical Engineer I'm pretty sure the modifications I made are about exactly the same as what Browning did to their production 300 RUM's and did not reduce the margine of safety of the action. I'm pretty sure my action will hold...but I don't recommend anybody else try this at home!

This is why serious African hunters like the .300 and .375 H&H....

I have good news for you, The 300WSM feeds perfectly in my Rem 700 300 Ultra Mag action. I loaded 3 rounds in the mag and they loaded into and fed out of the mag as well if not better than the full length Ultra about 100 rounds in a row. It does not jump out of the rails too soon either, that's what I wondered about mainly. The case dims are practically identical with the WSM being just .750" shorter is all. The WSM cartridges I tried were about .008" larger at the base so they will stick if slammed forward all the way. They fed perfectly. My 300WM was a little too narrow in the rails to load and feed but would work as well. I like the 300 Ultra conversion though, it was slick, almost perfect. You should check it out. Hope that helps.
No sweat Troy. I had been curious myself and finally had the rifle on hand to check them in. I forgot the WSM was so close in dimentions to the Ultra case, no wonder it feeds so well. I'll have to find a barrel to install now, it's nice to be able to add this to the list of possible switch barrel combinations with the Ultras action.
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