Accuracy International stock on a 300 RUM

I shoot at a range where they sell AI stocks, and the only rounds that fit in the detachable mag are the ones based on a 300 win mag. the shoulder on the RUM is too far forward to work in the mag. this is what i have been told, someone may know better than I.
Gene Cole III
I build a bunch of 338 Lapuas in the Rem/ AICS combination. The Lapua magazine might feed the RUM.

[ 06-23-2004: Message edited by: chris matthews ]
The rifle and stock are on the way. Hoping this all works out. My buddy thinks it will be a go but a small modification to the action to adjust for a change in the feed lips of the magazine will be required. This will prohibit the use of the action in other stocks (other than an AICS) because the modification is to the feed ramp area. Still hoping to get input from someone that has accomplished this already or that has any input. Thanks.
You won't have to change the feed ramp at all. The lips of the mag might need bent in a tiny bit. Put it together and try it first before you start modifying stuff.
Tried a RUM case in an AI Lapua magazine today and it will not work. The lips are fine but the shoulder of the RUM case hit's two indentations on the mag. Without a large bit of modifying, I'm afraid your stuck witha stock that won't work with your caliber.
I was afraid of that. I guess that is what makes this such a great sport...figuring how to make this kind of thing work. Thanks for the input Chris. I am going to talk to a fabricator today about making a new follower for the magazine or if altering the magazine body will be required.
The problem with the Remington Ultramags in the AICS magazines is the length of the rim to the shoulder. The two deeply stamped strengthening ribs in the magazine body are placed too far back for the Ultramag brass to fit. The .300 Ultramag is 2.387" from rim to shoulder. The .338 Ultramag is 2.296" from rim to shoulder. The .338 Lapua is 2.161" and the .300 Win Mag is 2.196" from rim to shoulder. That's the reason why neither the Lapua or Win Mag AICS magazines will work with Ultramag brass without modification. One solution is to remove the strengthening ribs via grinding or machining. The magazines then have an open slot machined in them that exposes the cartridges,follower and spring to foreign material. People have done the modification,but they have to come up with some way to cover up the slots.

It has been done successfully with the use of the .338 Lapua magazine, the front ribs have to be machined out to allow for the RUM's extra shoulder requirements. This will allow the .300 and .338 RUMS's to function with x5rds very successfully. Of course, once this modification has been done, it will void any warranty/repair/replacement with AI on that particular magazine.
The .300 RUM will fit after modification, but, the magazine will become weaker right?

Bah I would love if Badger Ordnance, Remington, Accuracy International or any other High Quality company made those magazines from factory, studied and designed to avoid those modifications..
I shoot a 338 ultra mag out of my AI stock with no problems at all,feeds smooth and quick.Mag was adjusted by a AI dealer and has worked great.
I'm using the lapua magazine,cost was 40.00 for the adjustment mags came
back looking clean and new.
what benefit are you seeing by using an AI stock?? they are heavy and over priced. I don't see the point even for a tactical rifle.
Chris Mathews you are incorrect on your evaluation on the ultra mag, Cummins Cowboy who said any thing about a lite tactical rifle,if you can't afford a AI stock don't buy one.

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