12" 6.5 Grendel Update 5 month Review

[RVTMaverick]

Hey Mark, As for Me and Mine, We'd love to see your results, of Your Playing<OOPS!> I mean having FUN!
Starting another Thread ofcourse...
Peace Jeff

All of this has me thinking of a project. Two shorties, 6.5G and 5.56 stainless match barrels, in the same toolbox. Furthest within one hour is 600, option is to take them with me up north at work and go to 1200. Just for fun, nothing more.

[LRRPF52]

Just got a 10.5" Criterion barrel from Precision Firearms last month.

Will build up an upper with it when I get a chance.

Been mega busy.

[maximus83]

@LRRPF52, nice! Just got my 6.5 upper from Mark at Precision Firearms this week, the one I told you about earlier. It was a long wait, 5 months from the date of order to the day I received it. I think his reputation for accuracy and quality is getting around and he's getting a pretty huge backlog.

Look forward to hear your range report on the Criterion, especially how it does beyond 500y.

[LRRPF52]

So here’s my 6 year update on the 12” Grendel after years of DM courses and range trips.

This compact blaster has just been a joy to shoot. My main use for it is going out and ringing steel from 150-900yds, as well as a lightweight go-to, all-round performer.

Practical Portability
It packs into a small weapon case that is easy to throw in the vehicle and go, vs the bulky, heavy, longer cases that still find a way to make life harder in the back of a larger SUV. When you’re loading tripods, spotting scopes, multiple range bags, medic bag, shooting mats, water, coolers, and other cases, it’s so much easier tossing a short bag in along with the rest of them.

I’ve had my youngest boy training on it now, learning fundamentals, and now shooting with it out to 780yds. It’s a great platform to train on since you can more easily see your sight picture and impacts on-target.

This past week, I made multiple consecutive hits on steel at 780yds without misses, then tried my hand on a 900yd 12” plate and connected 1st-round with witnesses. Even after shooting long range regularly since 1995, I was a bit tickled with that.

Here’s a pic through my Leupold binos with mil reticle where you can see the 400yd plate and 780yd buffalo sil. The 900yd plates are off the the right of this.



Suppressing 12” Grendel
The TBAC Ultra 5 (1st Gen) has never come loose on me, so that conical angle and threads seem to really work well with their brake-attach. At my last DM course a fews weeks ago, we saw some crazy fireballs coming out of it at night when shooting Wolf steel case, so I’m guessing Barnaul doesn’t use powder with flash suppressant. The TBAC Dominus wasn’t available back when I got the Ultra 5, so I would go with that can for the 12” if it had been an option I think.

The Faxon group buy Monster logo barrel has been great, holding accuracy well enough for me to make hits that are normally considered bolt gun territory at stupid distances. I normally don’t buy lower price point barrels, but wanted to see how these turned out. So far, so good. I also checked with my friend whose sister 12” Grendel I built with the same core components (Faxon Group Buy Monster Logo barrel, Bootleg Adj Gas Carrier, Monster logo bolt) and he hasn’t had any FTFeed, FTE, FTFire issues at all running 107gr SMK on 8208 XBR.

The Bootleg Adjustable Gas carrier has been performing as-advertised, set at fully-suppressed position. Ever since the stupid GATF stamp cleared, I’ve shot it exclusively suppressed (2018-forward). Runs very well-behaved even for small-framed shooters. Remember that the action spring is an extra power carbine spring, combined with a standard 2.9oz carbine buffer.

Ammunition has included:

Federal 90gr TNT
Wolf 100gr FMJ
PPU 110gr FMJBT
Federal 120gr OTM AE
Hornady American Gunner 123gr BTHP
Hornady Black 123gr ELD-M

The 120-123gr hit the steel targets much harder, at least from what you can hear. The 110gr PPU is surprisingly-flat shooting and I think their BC is either on or maybe even under-stated. I had to keep changing my data to get it to match yesterday as it was better than what the program kicked out. I had written the 110gr PPU off as good 300-400yd plinker ammo for steel, but after being so consistent with it at 780-900yds, I changed my mind about it. It still sounds like you’re hitting with a 6mm though, so impacts aren’t as audible.

I really need to load up the 130gr Nosler RDFs with their .615 G1/.307 G7 BCs. I like hearing hard impact on steel.



I’ve been using the LaRue MBT-2S trigger throughout, which is a great 2-stage trigger.

Optics
I originally had a discontinued GRSC 1-4x24 on it which I broke last fall shooting it at this same range. I replaced that with a 1-6x24 GRSC made in Japan at LOW, which is a tough scope that has held up on full-auto AR-10 testing. The 1-6x reticle has stadia down to 1200yds calibrated for 175gr 16” .308, which tracks well with 123gr 6.5 Grendel trajectory. Using the reticle BDC, you are easily able to hit plates from 100-400yds 1st-round.

I’ve been using the LaRue SPR 1.5 mount the whole time. Have not had any issues with looseness of the base or rings, (followed the distractions for install).

Mags
There are new ASC mags I’ve been using, along with Amend2, Elanders, and CPD, that have all been flawless. They seemed to have refined the design on the later ASC mags and it shows in the fit/feel/finish/function. I bought several 25rd ASCs to try out within the past few years. I de-edge, blend and polish my barrel extension feed ramps on AR builds, and make sure the ejector is radiused to prevent right side feed presentation hang-ups.

I’ve had one notable malfunction after the Wolf steel case was run through it at night, then the next day, had FTEx with brass case PPU. The Wolf really built-up a lot of soot in the chamber, especially running suppressed. This is the same problem I’ve had with numerous 5.56 blasters as well going from steel case to brass. Cleaned the chamber when I got home with a 6.5 Grendel-specific chamber brush and not a hiccup since. I prefer shooting brass-cased ammo, but a guy needed a loaner blaster since his POI was way high at 100yds and didn’t have any bottom left with the way his zero stop was set up, so he borrowed the 12” and ran steel through it.

Things I would have done differently, knowing what I know now:

* LaRue Stealth 2.0 Upper and Handguard combo in FDE (no problems with what I have, just that the Stealth 2.0 looks great and is truly free-floated with no contact between barrel nut and the handguard)

* I go back and forth on whether I should have gone with the TBAC Ultra 7 for being really quiet, vs the Ultra 5 for compactness. Had it been available then, I might have gone with the TBAC Dominus K-SR or the Gen II Ultra 5, which is even quieter and lighter than the Gen I that I have. I never complain about the Ultra 5’s compactness and lightweight, which delivers 100% of the time. From shooter’s perspective, it takes enough of the edge off of muzzle blast. The Ultra 7 used on the other 12” is noticeably quieter like what you would normally hear from a suppressor on a much longer barrel centerfire. The Ultra 5 I have is only 7.4oz, which doesn’t even feel like a suppressor on the end of the barrel, and more like a blank firing adaptor.

I have a Vortex Gen III 1-10x I haven’t even installed, which will likely make it easier to TGT-detect and shoot due to the generous FOV and clarity. I’m also looking at the March 1-10 Shorty Dual Plane FFP with DR-TR1 stadia tree reticle. A clip-on would be sick in conjunction with the tiny March.

Out of the roughly 2-dozen AR’s I have, this is now my first-grab. I don’t see myself going any longer than 12” in the future due to the downrange results I’m getting even with cheap PPU ammo, let alone Hornady 123gr ELD-M, AG, and Federal OTM 120gr SMK. There is a noticeable audible difference in how hard 120-123gr hits vs 110gr PPU FMJBT. 110gr sounds like 6mm hitting the plates, which has always been less-than-ideal. I’m the type of guy who likes the sound of 168gr or 175gr SMK .308 hitting steel, but also want to see my own hits without the sight picture yanking off-target on lightweight blasters. With 6.5 Grendel, you get the best of both worlds: minimum sight picture disturbance and sounds almost like 168gr SMK impacts.

[B Cart]

Awesome report, thank you. I've been running a 12" suppressed 6.5 Grendel now for a few years, but it's mainly for coyote hunting, running the 90gr TNT ammo. I hunt a lot with it at night under Thermal (and I run a Vortex Viper PST 2-10 on for daytime hunting), so most of the shots aren't too far, but nice to know you've had success at long range. I shoot a lot of long range here in Utah, and I typically use other guns/calibers for that, but now you have me wanting to stretch the legs on my 12" Grendel lol.

[LRRPF52]

Awesome report, thank you. I've been running a 12" suppressed 6.5 Grendel now for a few years, but it's mainly for coyote hunting, running the 90gr TNT ammo. I hunt a lot with it at night under Thermal (and I run a Vortex Viper PST 2-10 on for daytime hunting), so most of the shots aren't too far, but nice to know you've had success at long range. I shoot a lot of long range here in Utah, and I typically use other guns/calibers for that, but now you have me wanting to stretch the legs on my 12" Grendel lol.

A friend of mine brought his 12.5” Odin Works Grendel, suppressed, to one of my DM Courses last month and made a 1st-round hit on a 12” steel plate at 760yds shooting Hornady American Gunner while I was spotting for him. It was another cool moment.

That 780yd buffalo target is kind of boring to shoot even with the short Grendels with LPVOs. It’s 36”x24”. If you look down and to the right of it, you might be able to see the 12” plate. There’s another plate up and to the right of it at 805yds that very few precision rifle shooters are able to hit 1st-round even with magnums, 7mm, 6.5 PRC, 6.5CM, etc. This is in Central Utah at North Springs, the coolest range complex I’ve seen from all my travels around the world.

That 90gr TNT load is very fast for me even from the 12”, doing 2700fps. Does 2900fps from the 17.6”. I’m sure you’ve seen DNS’s hunting videos with 90gr TNT.

One thing that has changed my mind over these past few courses shooting that 110gr PPU FMJBT is that I don’t see a need to do a 6mm anymore. I’ve always planned to do a 6mm AR ever since shooting my buddy’s 20” 6mm AR, which was basically necked-down from Grendel with no need for any other processes. The 103-110gr bullets just don’t cut the mustard for me impacting steel at distance, whether 6mm or 6.5mm. Yeah, it’s easy to make hits with them, but the sound just doesn’t give me the dopamine hit I’m looking for.

If I want that experience, I can just shoot 107gr SMK really flat and get the same “think” on the target. I’ve spotted for 6mm Dasher, 6 XC, 6CM, 6x47 Lapua, .243, .243 AI at matches and events over the past 2 decades and while they hit hard within 300-400yds, they really start dropping off in audible impacts after that, especially once you get out to 650-700yds. There’s nothing you can really do to make it hit audibly harder either. They connect fine with almost no recoil, but just fall short in loudness.

123gr 6.5mm is just louder, sounds more like .308 Win, without the recoil/sight picture penalty.

[B Cart]

A friend of mine brought his 12.5” Odin Works Grendel, suppressed, to one of my DM Courses last month and made a 1st-round hit on a 12” steel plate at 760yds shooting Hornady American Gunner while I was spotting for him. It was another cool moment.

That 780yd buffalo target is kind of boring to shoot even with the short Grendels with LPVOs. It’s 36”x24”. If you look down and to the right of it, you might be able to see the 12” plate. There’s another plate up and to the right of it at 805yds that very few precision rifle shooters are able to hit 1st-round even with magnums, 7mm, 6.5 PRC, 6.5CM, etc. This is in Central Utah at North Springs, the coolest range complex I’ve seen from all my travels around the world.

That 90gr TNT load is very fast for me even from the 12”, doing 2700fps. Does 2900fps from the 17.6”. I’m sure you’ve seen DNS’s hunting videos with 90gr TNT.

One thing that has changed my mind over these past few courses shooting that 110gr PPU FMJBT is that I don’t see a need to do a 6mm anymore. I’ve always planned to do a 6mm AR ever since shooting my buddy’s 20” 6mm AR, which was basically necked-down from Grendel with no need for any other processes. The 103-110gr bullets just don’t cut the mustard for me impacting steel at distance, whether 6mm or 6.5mm. Yeah, it’s easy to make hits with them, but the sound just doesn’t give me the dopamine hit I’m looking for.

If I want that experience, I can just shoot 107gr SMK really flat and get the same “think” on the target. I’ve spotted for 6mm Dasher, 6 XC, 6CM, 6x47 Lapua, .243, .243 AI at matches and events over the past 2 decades and while they hit hard within 300-400yds, they really start dropping off in audible impacts after that, especially once you get out to 650-700yds. There’s nothing you can really do to make it hit audibly harder either. They connect fine with almost no recoil, but just fall short in loudness.

123gr 6.5mm is just louder, sounds more like .308 Win, without the recoil/sight picture penalty.

Definitely love North Springs, i've shot and competed there many times. It's a world class range for sure! Most of my long range shooting is done with my 6creed, 6x47 Lapua, etc., but I'll have to play around with the 107 and 110gr projectiles for the grendel. I still have a bunch of 120 OTMs that shoot really well out of my gun, but those just don't quite have the velocity.

[Disciple]

Awesome report, thank you.

Ditto.

[LRRPF52]

Somone asked about some of the build processes I use, which are based on the experiences of others who have paved the way back when negotiating through how to get larger cartridges to work in the AR-15 action.

One thing the guys who were building 6mm PPC, 6.5 Grendel, and 6mm AR AR-15s for High Power back in the day realized was that the rim of the brass could get stuck on the side of the ejector when feeding from the right side magazine presentation.

As the cartridge rises into presentation from right side, is stripped and fed into the chamber, the rim settles into the bolt face from the right side. They radiused the ejector so that a rounded surface would allow the case rim to slip over the ejector and into alignment, rather than binding up and causing a FTFeed. I do this on all my Grendel builds before even letting the bolt get assembled.

I just make it slightly rounded like the Dutch did with the AR-10. Alexander Arms approach was to just make sure the ejector wasn’t too long, which is easier to control and duplicate from a production standpoint.



This is what my extensions look like when I’m done de-edgeing, blending, and polishing. As part of the blending process, I constantly check with the upper that the feed ramps don’t hang over the feed ramps of the upper, because this creates a lip for the meplats of projectiles to catch on or shear. I want the cartridge to have the most smooth transition from the magazine, up the ramps, and into the chamber as possible.



There is a long list of things I do before I let a barrel/bolt combo move forward into being assembled with the upper. I don’t just slap parts together and hope for the best. I have at least 4 dummy cartridges with different projectiles and their ogives and COLs to check the chambers with before I call the chambers good, with known headspace set for those dummy cartridges. Gas ports have to be the correct diameter, and the carrier has to have correct tri-bore dimensions internally. Extractors get worked if they have the sharp corners on the lip, which can hang-up the ejection or thrash your case rims.

I also like tight-fit barrels, either interference fit, or tight fit with Loc-tite bedding after I have squared the receiver face with a lapping tool.

Gas blocks get bedded per recommendations from Bill Alexander after he fleet-tested his initial rifles. I also bed the gas tubes and ensure proper alignment with the tube and the carrier key. Then there are all the torque specs for muzzle devices ( I want as low of a torque value as possible at the muzzle per AMU lessons-learned), barrel nut torque (different for barrel weight), and scope rings.

[LRRPF52]

Regarding magazines. These are the magazines I have run through the 12” so far:

* Older CProducts Defense, including 5rd, 10rd, 17rd, 25rd
* Elander 17rd and 25rd
* Amend2 Polymer 10rd
* New ASC 25rd

The new ASC 25rd mags I have look like they have refined them and tightened-up their QC, so fit/finish/feel/function have improved. I dealt with some older ASC mags in 2010-2012 timeframe that had different feed lip angles, with one that needed to be modified to fit for a guy who sent it to me. I’m not seeing that on any of these new ones I have, and they have fed and locked back after last round so far through the 12” and 17.6” Grendels without a hitch.

All the other mags have fed and functioned flawlessly as well.

As a hand-loader, I personally like the CPD and ASC mags for the longer allowable Cartridge Overall Length (up to 2.285”), while the Elanders will only run 2.260” COL ammunition.

For shooting off a bench or prone where ground clearance is consideration, the 10-17rd mags are preferred. For everything else, I really like the 25rd mags.

A 25rd mag of 6.5 Grendel has more stowed connects in it than a 30rd 5.56 mag due to wind drift, once you start pushing past 400yds or even at 400yds once the wind pushes past 5-7mph full value, and the 5.56 hits with such a pathetic impact as to be very minimal juice for the squeeze.