question about 700 ultra mag actions

HH .338 · #1 02-26-2003, 09:02 AM

hey guys i have a quick question. are all the ultra mag actions (7 rum 300 rum and 338 rum) the same dimensions? are the mags that come with the 300 rum and the 338 rum the same size (will they both allow the same max oal for a loaded cartridge?).
reason i'm asking is because i intend on purchasing a 338 rum first, using it and when i have more money i would like to put a long tube on it and a mcmillan stock. when i do put a new tube on though i might as well go with the 338/300 rum imp version rather then a standard 338 imp version. will i have any problems doing this on a 338 action?

later

Mysticplayer · #2 02-26-2003, 01:40 PM

The factory actions for these 3 cartridges are the same dimensionally. The only problem with your goals is that if you want to use heavy and long bullets, the mag will not allow for seating these bullets out.

You are forced to stay within the factory max cartridge lengths which is too short for the 300gr MK or similar LR bullets. In this situation, single feed is the only alternative.

Jerry

Brent · #3 02-26-2003, 02:34 PM

Brownells has a mag box you can fit yourself with very little modification to the rear of the action. It comes with instructions on what to file off, where, and how much. The length on it is 3.91" I believe. My Ultras box is about 3.675".

You will not have any problem doing what you want with the 700. This is where the 338 Lapua case has an advantage, it makes up for some of the case capacity that the long bullets seated deep eat up, as it is larger in diameter and a bit shorter.

OAL on the 338 Lapua Imp is usually around 3.9" with the 300gr SMK. On the other hand, my brother seats his out to 4.1" on his 700 338/378wby and has to single feed them.

[ 02-26-2003: Message edited by: Brent ]

dwm · #4 02-26-2003, 08:34 PM

Sure wish I would have heard about the Brownells magazine box before I ordered the reamer for my 7mm RUM.

Spec'd the reamer so that magazine length catridges would be 0.005 inches off the lands.

Bet the magazine box is cheaper than the reamer and the barrel work. I did specify a tight neck also though, so at least I will have that going for me.

Brent · #5 02-26-2003, 09:47 PM

Dave Kiff at Pacific Tool can hook you up with a throat reamer for $66.00 if you change your mind and decide to extend it and get the long box. An extra 70 bucks at this point, but it still might be worth it to you if the barrel is still off. Just a thought. [img]images/icons/wink.gif[/img]

[ 02-26-2003: Message edited by: Brent ]

HH .338 · #6 02-26-2003, 11:30 PM

thanks for the info guys.

Brent:
i went to the brownells website and i think i found what you are talking about.
http://www.brownells.com/aspx/NS/sto...il.aspx?p=1405

that link should work i believe. it says it gives .110 additional length. that doesn't exactly sound like much but it might really make a difference. what do i know [img]images/icons/grin.gif[/img]

Sheldon · #7 02-27-2003, 09:18 AM

I wish they had something like that for the detachable mag versions. I have a .338 SS-DM that I would love to convert to rebarrel to a .300 Ultra...