6.5 Grendel Piston AR


March 3, 2012, 08:31 PM
Today was the test fire for the first AR-15 build. What makes this build unique is in the title, it's a 6.5 Grendel piston gun. Only put 20 rounds through it, mainly for function check, but there's 480 more where those came from. I'm pretty impressed, after a few rounds to break it in it went without a hitch, pretty good for the first time building I think. Accuracy was pretty good, but since it was mainly for testing today, there wasn't much accuracy testing done. Ammo was Wolf 120 gr MPT.

The plan is to build and sell these rifles as soon as possible, of course the legal things take a bit of time.

Of course, the obligatory gun pics...





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March 3, 2012, 10:23 PM
Very nice, good luck on the legal stuff, it can take a while sometimes.

March 3, 2012, 10:53 PM
Looks good, any thoughts about using that convenient little space on the underside of the gas block for another short rail?

March 3, 2012, 11:22 PM
That's a good idea. It looks as if some type of mini rail is already there, but I'm not sure what it is, but if it's a rail it's definitely not picatinny.

March 4, 2012, 01:09 AM
Its a bayonet lug. Looks like you are still new to the AR world but none the less good luck making a living selling them. Just make sure you do a good job and you should be fine.

March 4, 2012, 01:23 AM
Good to know, thanks. Bayonet lug on an AR never crossed my mind, I thought they were fitted over the barrel on ARs. I wouldn't call myself new, just hadn't heard of such a thing on an AR-15.

March 4, 2012, 08:42 AM
The Grendel is normally a long range rifle and a piston would be counter productive in that roll. What piston kit did you use?

When Wolf ever releases the 6.5G steel case plinking ammo then a 6.5 carbine or two well be added to my stable.


March 4, 2012, 10:19 AM
I read the title too quickly and thought it said "6.5 Grendel PISTOL". I was thinking, "who the hell would build an AR pistol using 6.5 Grendel???" But, then I realized. . . :o

I hope grendel uppers AND ammo start becoming more prevailant and lower in price because it is the long range rig that I want to eventually build.

March 4, 2012, 01:39 PM
I would rather the 30RAR take off so I could get a 6.5 or 7mm wildcat based on it, but to each his own I guess.

March 4, 2012, 02:12 PM
The piston accuracy is something we want to test and it will probably get posted here when we can take it out farther. It's a CMMG and has a special bolt carrier to reduce carrier tilt.

March 4, 2012, 07:12 PM
I really like CMMG.

March 4, 2012, 07:14 PM
The thing that makes pistons less inherently accurate as a system is the reciprocating mass attached to the barrel, which is a part of the whole "piston" package that can't be helped.

The direct impingement guns use a piston as well, it's just behind the barrel and is called the bolt carrier. They can be more accurate, all else equal, because there is no movement going on with the barrel, just gas flowing down the little pipe.

March 4, 2012, 10:46 PM
Right. I've been studying both systems for a while now and weighing the pros and cons of each, and our goal (or at least mine) for this one is to hit minute of bad guy at least 300 yds away. AK's can do that, and I'm hoping this can do better.

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