6.5 Grendel Build Questions

[Bret]

This is my first post on this forum, so please be gentle.
I decided to put together a light weight 16" 6.5 Grendel AR15 and purchased the following parts from Alexander Arms.

I've since gathered most of the remaining parts that I need including an Adams Arms piston system. I don't want to make any assumptions when it comes to this build. Is the barrel nut the same size as it would be for a regular 5.56x45 AR15 build? What's a good source for an inexpensive 9/16-24RH flash hider or muzzle brake? What's a good source for the crush washer?

[tommag]

I don't know if it's a good source price wise, but cncwarrior makes 9/16 24 stuff.
https://www.cncwarrior.com/SearchResults.asp?Cat=2015

[just_john]

I get most of my crush washers straight from ebay. The upper receiver threading for the barrel nut is the same, regardless of chambering. The receiver is the common denominator, not the chambering.

[85_Ranger4x4]

Alexander Arms has an A2 for like $15 with the crush washer.

Did your barrel come painted? I didn't think they did.

[LRRPF52]

Welcome aboard.

I wouldn't use an external op rod system personally.

The guns work fine with Stoner Internal Expansion operating system, for a lot less money and headache.

[Bret]

The upper receiver threading for the barrel nut is the same, regardless of chambering. The receiver is the common denominator, not the chambering.

I'm kind of feeling dumb for asking now that you've pointed out the obvious. I guess it's better to be safe than sorry.

Alexander Arms has an A2 for like $15 with the crush washer.

I looked again. When I purchased my other parts, it wasn't listed under the 6.5 Grendel parts section, so I didn't buy it. It still isn't. I found it today by going to their general parts and accessories and then muzzle devices. Now it would cost me another $12.26 for shipping. I might just get one off ebay.

Did your barrel come painted? I didn't think they did.

It came just like you see it in the picture.

Welcome aboard.
I wouldn't use an external op rod system personally.
The guns work fine with Stoner Internal Expansion operating system, for a lot less money and headache.

No doubt you're correct. I just want to do something different with this build. I already have several DI AR15's.

[85_Ranger4x4]

I looked again. When I purchased my other parts, it wasn't listed under the 6.5 Grendel parts section, so I didn't buy it. It still isn't. I found it today by going to their general parts and accessories and then muzzle devices. Now it would cost me another $12.26 for shipping. I might just get one off ebay.

If LRRPF52 hadn't pointed it out it did exist I probably wouldn't have seen it either. I figured freight would kill it.

It came just like you see it in the picture.

Interesting. I emailed them last week and they said they only painted the barrels for their production guns, they said the DIY barrels were left natural for the user to finish how they like. I was asking about the 18" barrels though, maybe they are different.

[Drillboss]

AA stopped painting the barrels about a year ago.

[Bret]

I have had these AA parts for over a year.

[85_Ranger4x4]

And now it all makes sense.

Thanks.

[Bret]

Believe it or not, after taking over three years I finally built this rifle. It did take more time than a typical AR15 build due to the Adam Arms piston system, but it all came together nicely.

The fluted barrel and light weight Adams Arms piston system help make for a pretty light rifle. I expected it to be somewhat front heavy, but it's really not.

I took it out today and put 180rds of Wolf 100gr FMJ through it. I started with an RZE Unimag (runs 7.62x39 100%). Unfortunately, I had a double feed during the second magazine, so I changed over to using an ELander magazine. It ran 100% after that. I put a total of 80rds through it in semiautomatic. Ejection was only about 6' away in to an area with a 2' diameter and I was using a regular carbine buffer, so this rifle is definitely not overgassed.

I then put the upper half on my M16A1 lower half. The M16A1 has an H2 buffer installed. Because of this, I figured that it might short stroke. Sure enough, this happened about five times. Ejection was only about 4'. I then replaced the H2 buffer with the regular carbine buffer. The ejection distance did increase. Unfortunately, a few cartridges failed to fire due to carrier bounce. To be fair, the Adams Arms installation instructions warned about this happening in full auto if using a regular carbine buffer. Their solution was to use an H2 buffer. Next time I'll try an H1 buffer to see if it will work. Perhaps it will work in the gap between a regular carbine buffer and an H2 buffer.

[sarky]

Nice build, I'm going the Adams arms build as well. I just don't like all that crap being blown into the receiver. The one issue I had was with the hand guard, hand to make sure I had enough clearance for the piston system. Found a hand guard that worked but had to modify the barrel nut slightly. I'm also running a JP enterprises captured spring buffer. Haven't taken it out yet, but am scheduled to do so the end of the month. I need to take photos too. Once I have it running to my satisfaction, it's getting a paint job.

[Bret]

Thanks. I took it out again yesterday and ran 17rds of Wolf 100gr FMJ through it with the Alexander Arms semi lower using an E-Lander 17rd magazine. It ran 100%. I then put the upper on the M16A1 lower and gave it another try with the H2 buffer installed. It ran two full 24rd mags 100% in full auto. The temperature was about 10deg more than last time and I was in direct sunlight. That was apparently all the difference needed to make it cycle reliably. I tried to find an H1 buffer, but have apparently misplaced it. I'll give the H1 buffer a try when I find it.