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4887 Views 7 Replies 5 Participants Last post by  Camp Cook
I read a nice article on another caliber conversion at http://www.6mmbr.com/gunweek068.html. It is possible to go 6mmAR (basicly a 6mmx39) with good results by using either 6.5 Grendle or 7.62x39 brass by simply FL resizing using redding dies for this caliber. A perfect 100/10x MR 31 Highpower target was shot with this caliber at 100 yards. All that is needed is a barrel and AK sized bolt. Good article which compares it with the .223 80gr, the 6mmAR using a 105gr Berger VLD, a 6mm BR Norma with a 105gr Berger, and the 6.5 Grendle with the 123gr Lapua Scenar. Good 600 yard caliber. There is also info at www.6mmAR.com. Soooo many nice calibers to think of.....
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Just shoot 6.5 G (6.5x39) it's good from 100-1200 yards from a 18-20 inch barrel.
With regard to optimum barrel length....


In general, in terms of MV, each inch of barrel is worth about 2 grains of weight, and longer barrels help
lighter rounds more than heavier rounds. I assume this is due to the speed with which lighter rounds are exiting the barrel AND energy is the square of velocity so at any barrel length a heavy round cannot be accelerated to the same speed as a lighter round with the same available energy.

The sweetest spot for the Grendel is 120gr. The 120 Norma harvests more KE from the Grendel case than any other round.
I just found this 6mmAR article on the Internet and then did a search here... so sorry for bumping this old thread after such a long time... its just that I want this cartridge in a conversion kit for my XCR-L Standard so much...

It would be an awesome deer/predator cartridge...

Has anyone here shot this cartridge?

Does anyone have updated info on it?

Terra I know your probably getting sick of me asking for a 6mm just bear with me for just a little longer I'm wanting to help RA make more money and would buy this in a heart beat... :blah:
I think we would ALL enjoy a 6.5 (WTF) for a nice deer rifle. I got tired of waiting so I went ahead and built three ARs in this caliber. I think the Grendel is fantastic, like it better than my 6.8 SPC. ;D
It's no secret here, I'm a big fan of the 6mm bore in many variations. The 6x45/6mm-223 Rem is a nice option for heavier slugs with good velocity. 80gr feeding from the mag, can't be too bad methinks! A wildcat based on a necked 6.8 to make it 6mm SPC, for all intents and purposes, would gain the short barrel benefits of the 6.8 but benefit in itself with lighter slugs (80-90gr nominal weight), more velocity and increased effective range over its parent 6.8 case.

I read up on the 6mm AR awhile back, even talked to its inventor on the phone about it and mentioned the XCR. To really take advantage of what the cartridge offers you'd have to use long ogive bullets and for 6mm that means 107gr typically. The lighter round would gain a touch more case capacity over the 120+gr 6.5 tips. You could probably use some lighter slugs (87-90gr) with more standard ogives and get impressive velocities but the shortened OAL would worry me in terms of reliable feeding and chambering as the rounds would have more room to get jostled around in the mag.

In the end however, I fully realize these rounds are for more limited and specific uses and that's about as far as they'd ever go. As long as 5.56 is the pill of choice (with the prices to match) it'll just be simple economics that it'll remain king for some years to come, even if a new military cartridge is announced tomorrow, it'd take a long time for surplused cases to make it into the commercial realm for the reloaders and for the market to want the next best thing to have any impact on pricing. Even the "SHTF" crowd that worries about such things realizes that they may be better rounds but I guarantee that if it came to that 223 would be easier to scrounge than 6.5G, 6.8 SPC or any of that other stuff.
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I agree the SHTF caliber will have to be a "common" caliber, like it or not.
I couldn't care less about a SHTF 6mm cartridge I already have an XCR in 223... I want a 6mm for hunting deer/bear/wolves etc with my XCR... 8)

but seeing as it is not likely to happen I'm now thinking that I am going to bite the bullet and get a 6.8SPC...
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