Can anyone point me toward a gunsmith in the Allen/Mc Kinney area that would be able to check/and or correct the headspace on a 6.5 Grendel AR?

I inherited the AR which I believe has an Alexander Arms barrel. Can't be sure since I don't see any markings of such with it installed. Mated up with a Spikes Tactical lower.

The rifle will function properly with the PPU ammunition that was with it, but locks up when I try to load Hornady 123 gr factory ammo.

When I say it locks up, I mean it will strip a round from the magazine, but it will not fire and it jams in the chamber, requiring significant pressure on the charging handle to remove the cartridge. Several times it jammed so badly that I had to "mortar" the rifle to get it unloaded. The Hornady bullets do show what I assume are rifling marks after jamming.

I'm thinking either I have a "short chamber" that wasn't reamed to proper specs originally, or the barrel wasn't installed properly. Either way with my limited expertise I'm only guessing . However if I am correct, can it be corrected?

Are there any marks on the bullets from the rifling?

In McKinney you have 1911 Academy on Hwy 380 past Custer going west. Then there is Allegiant Rifleworks on Industrial Blvd.

Yes, there are. Unfortunately I didn't think to take pictures to post.


Thanks, I'll check with them.

Sounds like a short throat. You could try seating them a little more to chamber the longer rounds. Just enough to see if it will chamber.

I think there is a discussion on the 65grendel forum about some Hornady ammo that others were having the same problem, bullets hitting the lands and not allowing the bolt to lockup.

The same has happened with 6mm ARC ammo.

Friend of mine had to seat the bullets deeper, from what the factory loaded them.

I guess I also need to compare COAL for the Hornady vs. PPU. I can't imagine there would be a significant difference ASSUMING they're both to SAAMI specs.

The COAL should all be about the same, but the ogive is what might be causing the problem. It would be the ogive measurement on where the ogive hits the rifling. Certain bullets have a shorter ogive to tip length, and when loaded at the standard 2.250" COAL, the ogive would be jamming into the lands. Without knowing what bullet you are shooting and the seating depth, it's hard to know that's the problem. But sounds like it.

Thanks for that input, Chad. The functioning ammo is what came with the gun and it's PPU stuff. I have no idea what bullet weight, etc., since it was already in magazines and there were no factory original boxes. However, the Hornady is the American Gunner bulk 123 gr BTHP.




Thanks to McKinneyHusker for the 1911 Academy info. While he doesn't have a range or go/no go gauges, he does have a water tank to conduct tests in and better quality calipers than mine to check dimensions. I'll report back here on findings.

UPDATE

The good guys at 1911 Academy in McKinney checked it out for me. In a nutshell, it failed BOTH go-no go headspace gauges. Definitely looks like it's one of the early non-SAAMI conforming chambers on this one. And it's a Type 1 bolt also.

Seems that I now have to decide on a replacement barrel/bolt, not that there seem to be any available anywhere at this time.

Hmmm...you would think that they could ream the chamber.

Glad I’m not the only one that has had to mortar a round out of the 6.5Grendel using Hornady 123 ammo. Hornady swears there is no problem yet other manufacturers work just fine.

Uncle Bubba - I did ask about reaming the chamber. Those folks don't have the reamers and said that it would likely be more cost effective to replace the barrel and the bolt with a Type 2.

Big Pig - In desperation I also tried some steel-cased Wolf ammo and had the same issue. Of the three ammo brands I tried, only the PPU functioned properly.

It may be just the wrong bolt face. If it truly is an Alexander Arms barrel, it should have a .136 depth bolt. If someone stuck a .125 bolt in it - you would have a short chamber.

It does have the shorter Type one bolt. I was originally told it was an Alexander Arms barrel, but that turned out to be incorrect. No markings at all on it so it’s a total unknown. I might try a Type 2 bolt but haven’t found one yet.

Bummer.

I know Scott Weichel at https://www.liveoakaccuracy.com has a reamer. He did a custom boltaction for me a few years back. He is in Wylie so not far from your location

Thanks, Kmon. I sent him a message tonight!

Group buy on the Grendel forum for bolts. Bolt link

The owner of that forum does group buys on mostly barrels and bolts to help offset the forum costs. It is still a small speciality forum for the Grendel that dates back to well before the SAAMI specks.

Thanks for the leads, guys.

I do have a question about just changing to a Type 2 bolt. Since I don't know what the barrel is headspaced for, I'm leery of just throwing a different bolt on. Then I also see this on the 6.5 forum:

Mk136 (also called Type 2) boltface depth, which is 0.136″. Fits barrels chambered to headspace with a 0.136″ boltface depth. VERIFY your barrel’s headspace with your barrel manufacturer.[i][/i]

I certainly don't want to risk an out of battery discharge or anything else.

What say you more knowledgeable Grendel folks?

Kmon1 you were correct. Scott Weichel at https://www.liveoakaccuracy.com had the reamer and was able to correct the short chamber for a reasonable price. Said he went in an additional .013! Test fired/functioned fine. Many thanks for the recommendation. Now I'm looking forward to getting it sighted in, FINALLY!

Good deal. My Grendel is one of my favorite toys.