7mmRM advice

[OLEJOE]

I’ve got a 700KS that I’ve hunted with for years. I haven’t hunted for several years but I retired first of November and got my rifle out and started doing some checking on various things. The shoulder of fire formed brass is.015” longer or further forward than unfired ammo. I never checked this before but is this an acceptable amount since it headspaces off of the belt of the case? The rifle has been exceptionally accurate for a light barrel hunting rifle and with the McMillan kevlar stock it is a very light hunting rifle that is surprisingly comfortable to shoot. I bought the rifle used probably 20 years ago but another question I have is if I rebarreled it to another 7 mag, what would be the best way to go? I think I’ll stay with a Magnum to keep the same bolt face and accommodate the magazine as is. Would the short magnums work properly with the long action? I’d like to get away from the belt if possible. Does this sound feasible? Thanks for any and all suggestions.

 

[Slim13]

If you’re using store bought ammo I wouldn’t worry about it. If you’re shooting your own reloads then you’re probably need to back your sizing die out a little.

Yes you can run a short mag out of a long action. Many do for a variety of reasons.

If you’re currently happy shooting a 7RM, already have dies, etc. why switch? I’m on my 3rd barrel with my 7RM. Belt has never been an issue for me.

 

[OLEJOE]

I’m very happy with the 7RM. It’s more than I need but the recoil with this rifle is very manageable. I have no complaints what so ever. Not all groups but enough of them to help my confidence when making a difficult shot in the .1 range. Was thinking one of the beltless magnums that headspace on the shoulder. Was wondering if the amount of case stretching I’m getting should be a concern or not. Thanks for the recommendations.

 

[Zero333]

If you reload then the belt becomes irrelevant because you move the headspace to the shoulder.

Use the comparator to bump the shoulders 0.002" like any other non-belted bottleneck cartridge.

One way to find out if the brass moving 0.015" is of concern is to sacrifice 1 piece of brass to see if it's thinned above the belt. If the thinning is significant, you can sometimes feel it with a slightly bent paperclip with out having to cut the brass lengthwise.
In my opinion, 0.015" shoulder movement is OK as long as it's not done more than once.

Here is a piece of 300winmag I cut to see if there was any thinning above the belt after several reloads. (nevermind the short neck,... I cut it for some other reason)

I used a dremel to cut it.

 

[OLEJOE]

Thanks for the suggestion. I’ve got an air die grinder and I’ll check it out tomorrow. I’ve been researching chambering options and I believe I’m going to stay with the RM. I guess I could just set the barrel back about .010 if it’s thinning the brass. RM ammo is available every where and mine is most accurate with plain old green box Corlokts. Nothing fancy but it works. Thanks again.
ps; I bought 8 boxes of it in Nov. of ‘07.

 

[OLEJOE]

ZERO333,
I cut a piece of the brass and it looks like yours. No thinning in the head region so I set my full length die to bump the shoulder back .002. I haven't reloaded for the 7 mag in quite some time and I bought a new press since then. The fired brass sized really easy and chambers easily also. I guess I'm good to go now. Thanks again.

 

[sbhooper]

I would stay with the standard 7 mag. It does not make any sense to go with a short cartridge, when you already have one that is great. Try to find ammo/brass for the 7 short and you will know which to do. If I was re-barreling, I would buy a Criterion, 26-inch, heavy sporter barrel from Northland (if they are available) in the standard 7 mag. I have one on a Savage action that is fantastic.