Interarms Mark X Rebarrel - Which Calibre?!

Hi all!

I posted in my intro thread that I've recently picked up a cheap Mark X barreled action. It's currently sporting a shot out .308 barrel but could accept a LA cartridge (which would probably feed slightly better too).

As I have a .308 already, I'm wondering what would be a good calibre option for a rebarrel. Primary use will be longer range (1000yds+) target shooting but potentially hunting as well, later on down the line. I'd rather not have the bolt face opened out so that limits me somewhat…

I handload so niche/unusual calibres wouldn't be an issue. It won't see a huge amount of use, either.

I'm tending towards a 6.5 or 7mm bullet. The Sherman family did appeal to me as I don't think there are that many over here in the UK! However a mate also said a .284Win could achieve 2,800fps with 180gr bullets and the right powder so that's definitely an option as well…

Any thoughts/experiences (positive or negative!) etc would be greatly received!

Many thanks,

Dr. S

280 Ackley. Anywhere from 8.4 to 8.7 twist.

Not being familiar with ammunition and reloading components in England I am wondering if a 7 x 64 would be a smart choice for you. Lapua has brass, Alliant has powder like Reloader 19 and Reloader 22, and bullets are readily available. Norma has a line of 7 X 64 ammunition and bullets. I shoot a 280 Remington and the 7 x 64 is almost identical to a 280 Remington. That Mark X action is a good action and like DJ Fergus said a twist of 1:9 of less would be good especially for heavier bullets but a 1:10 twist would also be good. I have a Timney trigger on a FN Mauser de luxe action and it is really good. Let us know what you decide.

Thanks, that could also be an option.

I'm currently leaning towards a .284 Shehane but more research is required!

Commercial Mausers are so under appreciated these days with all the fanfare going to expensive customs. A guy can build 2, 3 or 4 custom Mausers for the price of just one "you-name-it" custom. Not a dig at "you-name-it's" but I am a fan of buying the Mausers as projects; re-barreling, re-stocking and refinishing. I have 3 in process varying from 240WBY to 6XC to 8x68S and .284Win just completed. It's like working on British cars from the 60's and 70's. Simple, straight forward and fun!
FN Mauser, .284 Win
Sako L61R, 7mm Rem mag

I really liked what I read about the 284 Shehane and about the case holding 3.35 more grains of powder than a standard 284, and it talked about a 180 grain bullet with 57 grains of H4831sc and that sounded good until they got to part about long barrels.

what about the barrel? ...overly long?

When I looked at the Berger load data for a 284 Winchester their max load for a 180 grain bullet in a 24 inch barrel generated about 2700 fps. From what I read about the 284 Shehane the expanded case held 3.35 more grains of powder and they talked about using a long barrel to achieve 2900 fps. The 284 Winchester used 51.5 grains of H4831sc and the 284 Shehane load was 57 grains of H4831sc. It made me wonder how long the barrel would be to get the extra velocity.

well, if I remember correctly additional barrel length produces 30'-40'/sec per inch, so with the added powder, 26"-28" barrel length would probably get you to 2900fps.

apologies to the OP if it feels we are hijacking...

Not at all guys, all useful info, thanks!

I am fond of the Mauser actions, and have a Mark X in 7mm Rem Mag that I used extensively in East Africa 50 years ago. At my more advanced age, I don't enjoy shooting it as much as my smaller calibers, like 6 and 6.5 mm.

While you're looking for a re-barrel caliber, don't overlook European cartridges. If you're looking for a moderate cartridge for 200 pound (or smaller) game, you might consider a 7X57 (also called .275 Rigby on your side of the pond). A friend picked up a very nice rifle made by Rigby and marked ".275 Rigby", and I am sorry I did not see it first. Beautiful rifle!

If you want a little more power, you could go to the 8X57 or even the 9.3X62, which I used to own but finally decided my shoulders didn't like. Those are nearly 100 year old cartridges, but definitely not obsolete!

There are, of course, an abundance of more recent calibers that carry nicely out to 1,000 yards, but which also let your shoulder know it is taking a pounding.

Good luck with your choice and let us know what you decide.

If you were in the US I would suggest you consider (for something different and cheap) sending it to JES to be rebored/rechambered to 338-06, 35 Whelen, or 9.3x62. Cost is only $275 including return shipping.
But you're in UK and interested in smaller bore. So just tossing out the idea in case it helps others.

Cheers,
Rex

I have re-barrelled and re-chambered many Mausers over the years. My favourite hunting caliber in a Mauser was the 338-06 and my favourite shooting caliber in a Mauser was the 30-06 Ackley. The '06 AI was a particularly good shooter and, in my mind, the best of the improved calibers for efficiency and value, especially with some of the newer powders and bullets. Just my opinion.

Dr Strangelove said:

Hi all!

I posted in my intro thread that I've recently picked up a cheap Mark X barreled action. It's currently sporting a shot out .308 barrel but could accept a LA cartridge (which would probably feed slightly better too).

As I have a .308 already, I'm wondering what would be a good calibre option for a rebarrel. Primary use will be longer range (1000yds+) target shooting but potentially hunting as well, later on down the line. I'd rather not have the bolt face opened out so that limits me somewhat…

I handload so niche/unusual calibres wouldn't be an issue. It won't see a huge amount of use, either.

I'm tending towards a 6.5 or 7mm bullet. The Sherman family did appeal to me as I don't think there are that many over here in the UK! However a mate also said a .284Win could achieve 2,800fps with 180gr bullets and the right powder so that's definitely an option as well…

Any thoughts/experiences (positive or negative!) etc would be greatly received!

Many thanks,

Dr. S

Click to expand...

The 6.5-06 is a great cartridge for what you've described. I decided to step up and had a 6.5x280AI built which easily duplicates the 6.5 Brenneke ballistics and even slightly exceeds them with modern powders.
6.5 RWS is another option, but brass availability could be an issue. I know it is over here!

Best wishes with your project!

Ed