Over the years, I've slowly learned to like this cartridge more and more, and they are replicating like Gremlins now.  I'm even thinking my retros need to be Grendel's.

I like that the recoil is basically like an SKS, but the impact is much closer to a .308, especially when compared to .223 Rem, no matter what target bullet you try in the mouse guns.

Punching Steel

17.6" Lilja Barrel



16" AA Barrel-Target is just above the red dot in the picture getting smacked, with dust kick-up from the spall.


18" Midway Fluted Barrel

Curious what the extension looks like. That double dent looks like it is happening in the star chamber.  Perhaps entering the chamber at an extreme angle and denting on the top side.

Almost looks like the results of an M4 cut barrel in a non-cut upper?

Ok, I have been following this thread for awhile and finally succumbed. My first 6.5 Grendel:

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Assembled last night, will function test tonight and sight it in this weekend. I need to find a 200+ yard range near me. I have a big mountain in the backyard so this is going to be my (soon to be suppressed) hunting gun for everything except elk.

Aero M4E1 lower
Aero upper without forward assist
Odin Works 12” barrel
Odin Works BCG
Odin Works adjustable gas block
ALG V3 10” rail (with Big Igloo privilege)
Generic thread protector to save weight and length
Magpul K2 MOE+ pistol grip
SBA3 brace
CMMG lower parts kit
Geissele SSA-E trigger (with CW West privilege)
Geissele Maritime Bolt Catch
Burris 1.5-6x MTAC in a LaRue mount I had laying around

I’ve never named a weapon before but Purple Rain somehow feels appropriate.

I’m probably too late but on that Vltor receiver , check the pin groove in the threads, I just did a Grendel build with a vltor and mine ran off center causing the lugs to not line up. Took about .020 off one side with a file, and used green loctite retaining compound to counter rotation

No factory ones that I know of, but it's a good length to cut for a P&W with certain QD brakes like the Dead Air and LaRue Tranquilo.

My 18" Grendel should be here in 3 days. Super stoked to finally get one.
As far as glass, how much is too much in your opinion? Is that even a real issue?
Goal would be target and steel shooting as far as possible and hunting to 400 yards.

Saw the new Vortes Strike Eagle 5-25x56 that just came out. I really like it but I dont want a rifle that will flop over on me every time I set it down on the bipod or is too top heavy to hold correctly.

Think you will be happiest around 15-16X as your maximum magnification.  Once you get up into the magnification you are looking at, the size and weight start to be too much.  I regularly shoot 800 with my G and 15x is my max.

well my PSA barrel wasn't cutting it for me (just shy of 2MOA with Hornady Black) so I threw one of the group buy barrels on it instead.

Now for our POS gun-grabbing cunt in Annapolis to knock off the stay at home bullshit so i can go to the range....

What magazines?

Best I've been able to eek out of my two different 12" barrels is about 2MOA which, while not terrible, isn't gonna cut it for me.  So I guess it's time for Wilson Combat.  Should have known better at first but....oh well.

Which manufactures?

Why would you want a 6.5 Grendel with a short barrel?

Both my 12" Grendels are lasers with 90gr TNT hand loads.

As for why, they are much lighter and more handy than my 18'' G. And still have plenty of knockdown power for hogs or deer. They are my favorite AR's.

Compact package that can reach out several hundred yards if needed.

Why would you want an enormous bulky unweildy lodgepole of a gun?

Unless you only shoot from a bench, I suppose it would work okay in that instance.  I prefer adventure.

One is one of the "monster" ones which used to be GB on the 65grendel forum, but the guy has his own website now selling them. Did plenty of seasoning rounds with wolf cause everyone says the barrel needs to "settle" (though mine weren't exactly mexican jumping beans so idk wtf that's supposed to mean).  after about 200 rounds i'd put black ELDs, alexander arms 123 scenars, and 120 ELD, 123 ELD, Monster Match 123, 107 SMK, 120TTSX over Tac, 8208, and ar-comp.

2" at 100 and nearly 5" at 200 was the best *ANY* of the above would do, for myself and another shooter, both of us dropping 10-round sub-moa groups from other rifles the same day.  Barrel nut was torqued to the letter according to published instructions, all attachment points (scope/mounts etc) were torqued and loctited and verified to not be loose during shooting (i always take tools to the range just in case).  Scope was swapped out, the rifle it went to continued shooting very well and the grendel still shot "un-good" with a different scope.

Other uppers utilized on the same lower shot great.

One gets what one pays for of course, so it is what it is, i'll just get a wilson combat barrel cause i know they work.

Very capable medium game pistol.

I also have a blackout SBR and wanted to play with other non-5.56 calibers with it.  In the long run a 16-18" grendel can transit a lot less painfully if I want to, say, take it to Wyoming if I'm lucky enough to draw this year for pronghorn.  

The blackout's getting a wilson combat barrel too but that's just cause the tube has a *LOT* of rounds through it and it's not *AS* accurate as it used to be originally--it's still great and I may keep it around on another upper or just give to a buddy who wants a blackout and isn't as picky as I can be when it comes to killin rigs.

Come to think of it maybe I'll keep one of these 12" barrels around for him to play with too.  He's done a lot for other people so maybe I'll build him a 500-yard steel plinkin rig with it (range by us has like a 20" gong at 500 so it's not exactly a massive challenge to hit )

Been lurking here for a while but I can finally post some good news!

I am 300 rounds into my Grendel adventure. Started off with the PSA 18" stainless. A Bushnell Nitro 4-16x44 sits on top with their FFP reticle.
Immediately removed the barrel, trued the receiver and bedded the barrel back into it.

With American Gunner I really couldnt get below 1.25". Not that bad to be honest. I was able to shoot better at distance though. Averaging 1.75 groups at 300 and 2.5 at 400. I was really happy about that so I took it out last week and shot at 600, 800, 900, 950, 1100, and 1200 steel. After judging wind I was hitting at all distances.

Fast forward to yesterday... Reloads of 123 ELD-M and 123 SMK under 8208 XBR. 28 grains with the ELD gave me a .7" group despite a flopping target in 20 mph winds. Then 28.6 gave me a 0.55" group in the same conditions. Have not repeated them yet but I now have somewhere to start.

I need to get this dialed in soon because I am waiting on a 6 ARC barrel now....

Do you find that "True the Receiver" helps in a noticeable way? I have the same upper set waiting to be mounted.
I have the tool but never tried it. Do you blacken or coat the ground surface when done? What do you use?
Thanks.

Yes, squaring the receiver face works to find the most mechanically-true arrangement of the barrel to the upper, and even lug engagement of the bolt to the barrel extension.

It's even called for in the TDP.

Some companies have questioned it saying it can't be real, because when AR15 uppers are machined, the boring and final facing of the upper in the thread boss is done with a rotating tool that cuts it square, no way to make it not square since the boring tool and facing tool are done in the same operation.

This is true regarding how the upper receiver is machined.

What they failed to mention is that there is an anodizing process after all that, and that anodizing is not perfectly uniform, especially with how the parts are held to dry.

I've had this conversation with manufacturers where they have always had to be on top of their anodizers due to surface thickness variation, which not only affects dimensions on the outside of the part, but on the inside.  If the bolt carrier raceway is too tight, for example, and you get a bolt carrier that is on the larger end of the spec like some companies have purposely made, you will get sluggish cycling and failures.  These parts would be rejected in the Military TDP chain of custody and not allowed into weapons delivered to the DoD in most cases.

Anyway, when the face of the upper has uneven anodizing on it, the barrel extension flange will push against that uneven face with torque from the barrel nut, and offset the barrel slightly in the receiver.  When you go to zero the rifle, you will notice some mechanical deviation from mechanical true in the scope erectors.

On a squared upper, you will notice that your scope is already mechanically true and in alignment with the bore out-of-the gate.

If you lap the bolt lugs, you will also see uniform engagement, provided you have a quality barrel extension.

Most barrel extensions on the market don't even pass some of the basic TDP dimensional call-outs, so asking for them to be particularly uniform for accuracy purposes is already expecting too much.  One hopes to just get the bolt lugs to articulate through the extension teeth gaps without smashing into them or binding up, which is common on the cheap parts-bash companies and DIY builds.

Thank you very much LRRPF52.

Because I can't stop tinkering...

12" Grendel SBR with adjustable gas block. Anyone think it'd be worth my while to grab a lightweight BCG for the hell of it? Recoil isn't bad at all, I just like screwing around and seeing how nice I can make it.

Girlfriend has a 16" 5.56 with adjustable gas and a faxon lightweight BCG and Surefire SOCOM. Smoothest AR I've ever shot, I'm thrilled with how it turned out. Wondering if it'd be as nice of a change on the short Grendel.

It's basically necked down 6.5 Grendel. It is freaking awesome! It's the first one to get SAMMI. Hopefully it takes off as it gives us another option.

I wonder the differences between the 6mm ARC and the 6mmAR which has been around for years and is also based on the Grendel case.
I suspect the shoulder angle may have been changed, but what else?

The marketing. That's what else has changed.  

I found the answer on Accurate Shooter http://bulletin.accurateshooter.com/?s=6mm+arc&submit=Search:

NOTE: The rim diameter (0.441) and thickness of the 6mm ARC appear to be identical to the 6.5 Grendel as illustrated on page 40 of the SAAMI Industry Standards. From all we can tell, in other dimensions as well, this is a very close copy of Robert Whitley’s 6mmAR, a 6-6.5 Grendel wildcat. For example, 6mm ARC case length is 1.49″ vs. 1.51″ for 6mmAR. The Guns&Ammo report on the 6mm ARC states: “The 6mm ARC is based on the 6.5 Grendel. Hornady started by necking down the cartridge to 6mm and then pulled the shoulder back closer to the case head .030-inch. … Hornady also set maximum chamber pressure low at 52,000 pounds PSI. This slows extraction and makes it much less violent, prolonging the bolt’s life.”

So, just like the Grendel, don't read the primers and brass to determine if your reloads are hot.  If you get those pressure signs you are over the top for the cartridge.  Bolt versions can be loaded much hotter than gas guns so factory ammo will be light because of the intended firearms being ARs.  

I am sure it will have some high BC bullets but I doubt it will bite hard.  No matter what folks may say here and I always stand by it, the Grendel is popular because the 6.5 bullets make a great deer round and most folks who dive into the alternative cartridge world of ARs do it for hunting or to be quiet with subs out of a 300BO.

In your experience are any uppers more or less trued "from the factory" than any others?  

Multiple threads on it.

There are several guys I know who have 6mm ARs and have had them almost as long as 6.5 Grendel has been around.

I've always wanted a 6mm AR, but didn't want to mess with forming the brass.

I guess it's not as big of a deal since it's a pretty simply sizing operation, load and shoot.

6mm ARC just brings factory ammo to the table for the first time, with SAAMI approval and factory brass.

Shoulder angle is the same, but shoulder location is .030" shorter, so a little less case capacity but not enough.

I think a longer shoulder location would make feeding more reliable, but Hornady would have to cover down on what the reasons were for locating the shoulder back a little.

Could have been driven more by optimum placement for VLD-shaped bullets with regard to shank placement in relation to the shoulder-neck junction (SNJ).

Theoretically, the 6mm AR Turbo should feed better from magazines since their shoulders are moved more forward, but they also have a 40˚ shoulder.

6mm AR Left, 6mm Turbo 40 Right


6mm ARC would be hard to visually distinguish from the 6mm AR unless your acuity can discriminate 30 thousandths.

My sample sizes in the hundreds probably isn't enough to make any a conclusion, but within the hundreds of uppers I've seen come through my hands, I have seen trends, many of which were driven by the particular time in the market, not just the retail source.

Colt SP-1 uppers that I've checked were dead-on.

BCM are normally square, and also tend to have tighter extension tunnels.

Most forged uppers are hit and miss, with more "miss" the lower the price goes.

I don't really care, since I have the lapping tool and square them all up anyway.

If I have a rather loose extension tunnel, I'll mask off the BCG raceway and Cerakote the tunnel to bring the ID in for a tighter fit to the barrel extension, then bed it with Loc-tite as well.

You can shim, thermo-fit ones that will not fit together at room temperature, or use thick adhesive or temp insensitive filler compounds.

AMU figured this out when they saw barrel flex and oil seeping through and around the barrel extension on an old A1 upper way back in the day.

It was a well-guarded "secret" within the armorers for the AMU for a long time that passed over to the "A2" look-alike target rifles, with concealed free-float tubes and sling swivel studs welded to the handfuard caps, which were welded to the concealed float tube.

The sights were all different with aperture inserts based on shooter preference, and really tiny sets of front sight posts as well.

They were very selective about the A2 forgings they used, with tight machining tolerances adhered to with square faces.

They double-sprung the A2 rear sight protective leaf housing as well so it wouldn't bias cock-eyed like they normally do, giving the shooter a square rear aperture to look through versus a twisted one.  If you look top-down onto an A2 upper, you'll notice the rear sight is slightly twisted and mis-aligned with the "carry handle".

No replies, said fuck it, ordered a lightweight carrier and another Superlative Arms adjustable gas block, I'll play around with the lightweight BCG in my 12" SBR first

With a lightweight carrier and CLGS, you're going to have to dial-in the system carefully.

I'm using Bootleg carriers as my go-to lately since they have adjustable gas through the ejection port with a flat head.

Yeah I've got a couple of bootlegs, just trying to see how far I can take it. I'm about to be laid off and have the rest of the summer off, need something 'productive' to do

How does the Bootleg carrier manage the gas it receives - lets it bleed out somewhere to lower the pressure? I has just 4 adjustment positions right?
I lile Bootlegs CamLok handguards...

I have always wondered the same thing. As well as how does the RCA adjustable gas key work.

Thanks for that.  I've been using the VLTOR MUR uppers for my precision-y builds...

It drops more in the carrier and upper

There's a rotational gas "valve" with descending port sizes in-between the carrier key and the Stoner expansion chamber.

The fully suppressed setting has the smallest gas port inside the valve shaft.

There are detent recesses in a track on the shaft, so that the valve maintains the position the user selects.

It's the easiest adjustable gas system I've used on the AR15, though I haven't played with all of them.

It's definitely easy, I really like em. I'm just go adjustable gas block and lightweight carrier to see how light I can get the recoil with my reloads, the Bootlegs are the way to go for most shooters for sure

I still can’t get my Criterion Grendel to feed. I’ve tried various mags but have not taken it out to polish the feed ramps because it’s bedded.

Does Grendel use the same feed ramps and barrel extension as 5.56? I’m wondering if that’s the cause.

So, ultimately all the constricted gases go through the receiver as opposed to the barrel with an adjustable (or venting) gas block.

By the way, I just received your two 6.5 Grendel Reloading Handbooks - very nice books and great information!

ASC and Elander

give your feed lips a bit of a tweak.  

Already have. I'm pointing at the feed ramps. They have a horrible surface roughness and I'm not sure correct geometry.

Like this.

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This 17rnd E-Lander runs well like this.  It allows the the round to feed more directly toward the chamber.

Don’t do to much.