12" 6.5 Grendel Update 5 month Review

AR/M4 Beyond 5.56/.223
1

I’ve had a 12" Grendel project in the works for a while. Finally got it together earlier this year, took it out to 800yds at one of my LR courses in May.

Even with a little 1-4x GRSC discontinued Korean scope, it was almost boring hitting a mini buffalo silhouette at 800yds.

Here’s the particular canyon range I’m talking about with the 800yd buffalo indicated with a red dot:

All the closer targets from 150-500yds were boring to shoot as well. I field-zero’d it on one of the steel bowling-pin like targets, then proceeded to use the stadia lines to engage further 18" steel plates. Thing was smokin’ steel right out of the gate, with a lot of audible impact on the steel to the shooter and spotters.

Muzzle climb is noticeably more than an 18" Grendel, but I was shooting with improvised support, no bipod, off the bench. I would say the recoil unsuppressed is halfway between an AK and a 16" or 18" Grendel, but definitely a little more muzzle climb than 5.56 when shooting 123gr from the Grendel.

I shot it another time after that at distance. All ammo up to that time has been 123gr Hornady American Gunner ($139.99 at Sportsman’s Warehouse for 200), and has run 100% like a champ. I expected to have problems with this set-up since I was testing 2 new major component systems at the same time with the Maxim Defense PDW, and a group buy 12" Faxon barrel. Instead, it ran like a raped ape, perfect 4 o’clock ejection, always locked on last round, just really nice cyclic rate behavior out of the gate with 123gr Hornady AG.

While I was at Scout camp last month, as soon as we got to the lake and put the boat in the water, I get a call from my NFA dealer, letting me know my TBAC can was free from jail. Had to wait a week, but what’s another week when you’ve waited for 10 months. This past Friday, I finally got to chronograph the little blaster with and without the suppressor to get some baseline numbers.

12" Unsuppressed 90gr TNT Federal AE, 91˚F:

2702
2681 FTFeed (The Maxim Defense PDW brace action spring is much stiffer than a standard carbine spring, so 90gr TNT wouldn’t fully cycle the action.)
2670
2642 FTFeed
2654 FTLock on last round

Avg: 2670fps

Suppressed 90gr TNT
2675
2658
2660
2671
2685

2723
2700
2690
2682

Avg: 2683fps

120gr American Eagle Suppressed, 12" Grendel

2360 2411 2384
2375 2398
2374 2397
2387 2349
2384 2406

Avg: 2384 fps

I’m using a Bootleg Adjustable Gas Bolt Carrier, and ended up turning it all the way to the Suppressed position. It’s a very easy system to use by simply turning the regulator with a small flat head, which is accessible through the ejection port-no need to disassembly anything.

So far, this little blaster is genuinely exceeding my expectations, and everything ballistics programs said it should do, it has so far at distance. I’ll be testing some better target bullets for distance, and hunting bullets for 200-400yds. Those include:

130gr Nosler RDF
107gr SMK
110gr Lehigh Controlled Chaos (1500fps expansion threshold)
95gr Controlled Chaos
95gr VMAX

2

Awesome range report!!

It’s funny because I was just takling to my buddy about starting a Grendel upper, and remarked that faxon made a 12" barrel. I just installed their 14.5" match gunner in 556, and want to get it out with my 77gr ammo and see what it will do.

For a hunting/SPR rifle I was thinking of building a 18" match gunner in 6.5 Grendel. What kind of velocity are you getting from your 18?

3

You and I think along the same lines. I’ve been experimenting with 129 gr. Accubond LR’s in this build. With IMR 8208 XBR, I’m getting just under 2100 FPS into one m.o.a with the Ballistic Advantage barrel. With the minimum expansion velocity of this bullet (1300 FPS), this load should theoretically be good out ~650 yards where I hunt

Sent from my iPhone using Tapatalk

4

Really like the build, LRRPF52. Can you get good cheek weld with that PDW stock?

5

I was expecting the Maxim PDW brace to feel like some kind of face grinder.

Honestly, it feels like a SOPMOD almost to me, to the extent that I never gave it a second thought after using it. It’s far more comfortable than an MP5A3, for example, and just not a detrimental factor in ergonomics as I feared it might be. Great little set-up for compactness.

Now that I’ve had the thing out for another 5 months, I have more updates.

Reliability has been 100% with 120gr Federal OTMs and Hornady 123gr American Gunner, which I buy locally at Sportsman’s Warehouse for 70cpr.

What I do now when I go to that particular range at the North Springs Range Complex is immediately take it out of the case, get into a hasty magazine monopod position, and shoot first on the 800yd buffalo with a best guess for wind. On at least 2 occasions, that has resulted in just off the edge, followed by emptying the mag on the buffalo, with the satisfaction of hearing the dings.

450yd steel is 10/10 even with loosened up fundamentals and the same 1-4x scope using holds from the 5.56 NATO M855 trajectory band, with about a 150yd zero maybe.

Looking at the difference in my brass with the Bootleg carrier, before I dialed it down to suppressed, the cases were coming out as one would expect, pretty dirty. After dialing to “S”, they come out much cleaner, indistinguishable from unsuppressed brass. At least with the Federal 120gr Match.

I’ve shot both the 120gr Match and Hornady 123gr AG at that range with no huge differences in results, which are more dependent on conditions (temperature). Barometric pressure is much lower up there at anywhere from 6400-6600ft ASL, depending on which part of the range you’re at.

I made a little graphic to show some comparisons between an AKM and a 12" Grendel shooting 123gr Scenar.

6

What a cool concept. Glad to see it’s working out well.

7

LRRPF, if you did not plan to run suppressed, would you still stick with the 12" or go up to 14.5 to get a bit more steam yet stay in your general length envelope?

8

Interesting and well explained. My re-interest in 6.5G just got ratcheted up a little.

9

PS, that 1" grid surface the guns are laying on-- where can I get that? I’ve been using giftwrap paper that has 1" squares on the back sometimes on a target backer to facilitate knowing where to dial things. Works fine but if that stuff you have might work better so I’d like to know about it.

10

No. It handles really well as a 12" and isn’t anywhere near as loud as a 10.3" 5.56, for example. I shot it that way while I was waiting for my can to get out of jail, and it’s quite pleasant. Velocity gains from 12" to 14.5" would be anywhere from 50-100fps, barrel and load dependent. A 14.5" with FH is still pretty compact with velocity not too far off of a 16" though. I’m looking at converting at least one of my 18" Grendels to 13.7" with a P&W brake, namely the Tranquilo. That brings it to 16" so I can leave the rest of the rifle as-is.

Impact on steel is pretty loud, since it starts out with more muzzle energy than a 20" 5.56 rifle, with BCs that are substantially higher than anything you could hope to load in 5.56 NATO.

In practical terms, it’s like taking a Colt Commando profile gun that hits with more energy than an AK in CQM (without AK recoil), then has hit probability like an SR25 at distance. I wish I would have done a short barrel long ago, but the stupid SBR garbage with ATF turned me off to that route, since I cross State lines a lot throughout the year for different shooting events. (I now know you can file your paperwork to include travel dates from 01JAN-31DEC.)

The evolution and refinement of pistol braces got rid of that excuse for me, and I can treat it like any other handgun in the eyes of the law now as a result.

As far as making hits on steel plates goes, the only main difference I see between this and an 18" for example, is it’s a little jumpier, but I haven’t shot it with a bipod yet. I normally shoot the 18" Grendels with bipods or tripods.

In all honesty, I don’t have enough scope on this little blaster, so I’ve been looking at March Optics 1-8x24 Mini, which is so small, only one scope ring with fit on it.

I’m building some more 12" guns as we speak. If I could have done this one over had it been available at the time, I would have used the LaRue Stealth 2.0 upper/handguard for it and gone with the Ultra 7 TBAC can, not the Ultra 5. There is a bit of a pop with the Ultra 5 .30 cal on such a short barrel, which TBAC told me there would be, but I really like the Ultra 5 and how quiet it is on 18" and 20" Grendels (Hollywood). I’ve got to listen to Ultra 5s at various matches ever since it came out when RO’ing, so I know how quiet it is, plus mine weighs 7.4 ounces.

What you get with an SBR/Pistol Grendel is:

  • More energy at the muzzle than 20" 5.56 NATO
  • Unexpected supersonic reach and transonic stability for such a small package (900yds supersonic at sea level/STD with 123gr Scenar or SMK)
  • More retained energy at 400yds than a 20" .30-30 Win. 150gr has at 200yds
  • Excellent barrier defeat on vehicles and cinder blocks
  • Excellent soft tissue terminal performance with controlled expansion projectiles (deep penetration and double caliber expansion)
  • Kills medium game like other center fire rifles that have more recoil and muzzle blast
  • AR15 compact platform and parts availability
  • 25rd magazine capacity

It’s a little do-all combination really.

11

I make my own clothing and gear, so those are cutting table self-healing mats commonly found at fabric stores.

12

The March would be quite an upgrade. I wonder if someone (maybe March) is making a set of rinds where the front one is larger? I’d find that more comforting than a single ring, even one that was say 40mm long.

I’m testing a March 1-10 and it’s top-notch.

13

OP, can share the overall length? Both with and without suppressor. Thanks.

14

30" with the can and the PDW Brace collapsed.

26.75" without the can, collapsed.

Will be shooting a bunch of 123gr ELD-M through it shortly, in freezing temps.

15

OP, I have been looking at building something similar having been inspired by this build.

I’m curious, since your build is running well, what buffer setup did you choose with the maxim defense brace?

16

Hmmmm.

I have been planning a 6.5 Grendel build.
But was planning a 18-20".

Now I am having second thoughts…

Nice build.

Sent from my SM-G930V using Tapatalk

17

The short spring and tiny buffer than came with the Maxim. The buffer is 2.9 ounces like a carbine buffer, but it is really short.

The spring is short, but very stiff and provides very positive return to battery.

I’m doing another one with the SBA3 brace on a standard carbine RET.

18

Just ordered a 12.5 Atheris Rifle 6.5 Grendel Upper to swap with my 19.5" 300 Blk upper on my suppressed SBR. Posted in the wrong forum, but incredibly excited for this to arrive and getting out to the range to try it out based on your experiences.

19

LRRPF52, you talked me into it. I’ve started collecting parts from EE to build a 12.5” Grendel pistol. Currently I have a lower with a pistol A5 tube, a BA barrel, SLR handguard. I’ll be ordering a Dead Air Nomad for it shortly. I think I’ll put my Leupold 2-7x on it as a placeholder, but in the long run, I’m going to have to score something with a proper BDC reticle. Any recommendations for a SFP ~8x variable for a short, field carried Grendel?

https://imgur.com/a/GNCNKlP

20

Not LRRPF52, but I’m planning on picking up the Razor HD 1.5-8 since they’re so cheap right now (discontinued, I believe) and seeing how close the BDC reticle is to my load. I’m shooting 129 gr. Accubond’s at 2100 FPS out of my 12.5”