6mm in an AR-15?

dusticles

dusticles

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With all of the recent non restricted receiver talk, I got to thinking that it would be fun to run a 6mm semi auto.

Initially, I thought of necking down the Grendel. Simple, right? Brass should be easy, then buy a set of 6.5 Grendel bushing dies and a smaller bushing and you're all set.

Of course, as a reloader, I have to ask if it's worth adding a 40 degree shoulder? I mean it looks damn cool. And there has to be some sort of tactical advantage ;)

So, this leads me to the 6mmAR Turbo and the non-proprietary 6mm FAT RAT. Sweet ass names too!

Either round should send a 105/108 grain bullet close to or above 2700 fps from a 22" barrel.

Now the hard part. Where does a guy find a smith with a reamer? Or, how much am I willing to spend to get one across the border? Ideally, I could just buy one and have Mr. Jury spin me up a nice little number.

Anything else about these little 6mm's a guy should consider?

The 6mm Grendel is still on the table too, btw
 
This build wil be from scratch so anything goes. As long as it fits in an AR-15.

The goal will be to get a heavy bullet out of the 22" barrel at around 2700

Also, I really like the idea of using the Lapua brass
 
How about a 6x45? (223 with neck widened)

Have no experience with this but been reading about it.
223 brass is plentiful and cheap and it does not seem hard to convert the brass.
 
Why not just buy an NEA/BCL 102 and install a 243 barrel?
Not exactly what you're asking for but would stomp all the other options and be easy to find brass and dies. Once you change everything the 102 sounds like a really nice rifle. :p
 
6-223 would be the logical choice for 55-90gr bullets, but with a 105gr I'd imagine to work in an AR mag would require it to be seated too deep, ogive would be below the case mouth. Even if it did work, the speeds with a 105 class bullet would be in the 2450 fps range from a 20" AR

6mm-22 Nosler would be a bigger furnace, not sure about ogive friendly use in an AR with the heavy bullets

6mm Grendel would be best bet, or better yet the 6.5 version :popCorn:
 
Custom made 6mm Grendel carbon barrels for AR

dusticles said:
With all of the recent non restricted receiver talk, I got to thinking that it would be fun to run a 6mm semi auto.
Initially, I thought of necking down the Grendel. Simple, right? Brass should be easy, then buy a set of 6.5 Grendel bushing dies and a smaller bushing and you're all set.
Send a 105/108 grain bullet close to or above 2700 fps from a 22" barrel.
Now the hard part. Where does a guy find a smith with a reamer? Or, how much am I willing to spend to get one across the border? Ideally, I could just buy one and have Mr. Jury spin me up a nice little number.
Anything else about these little 6mm's a guy should consider?
The 6mm Grendel is still on the table too, btw
Click to expand...

Dusticles, I could not agree with you more.
With the forthcoming of NR ARs in the near future, I'm also very interested in a caliber that would push a 6mm 100-105 grs @ ~27-2800 fps out of a lightweight, non restricted, accurate, affordable AR.
That's a 10% velocity gain with bullets with 10% better BCs. Yes, I know, numbers aren't absolute
Still, me think a ~ 20% gain becomes very interesting !!

I've started discussing with the owner of BSF Barrels the opportunity of having them make a run of custom 6mm Grendel, 20", 1/8" twist, .934 journal, 5/8-24 threaded muzzle.
I think his approach of carbon shrouding instead of wrapping is better and more affordable.
If we got a decent quantity order together, they could conceivably land here in the 550-600 $ ea. price range.

Anybody else interested ?
email me at pratique50@gmail.com to discuss it.
Pierre
 
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