Suppressors Ultra 5 on 12" 6.5 Grendel, Initial Results

[LRRPF52]

I finally got my Ultra 5 after a 10 month wait. Main reason I got it was after personally witnessing several Ultra 5s on 20" and 24" 6.5 Grendel AR15s, which is a wicked-quiet combo. Ray and Bill Alexander noticed that the Ultras in 6.5mm might be too efficient at suppression for the AR15 and its bolt carrier vents, causing more noise at shooter's ear from the supersonic venting, and that the 30 Cal was probably the way to go for the AR15.

Against normal recommendations, I wanted to push the limit with the Ultra 5 because of how impressive it is in terms of weight and compactness. I had a hunch I would be happy, and I have to say that I am more than pleased with the noise level suppression from a 12" 6.5 Grendel so far.

Shooter experience is very pleasant, very smooth, no bark-like effects like I've heard from Surefire Mini or the OSS cans. For my purposes, the suppressor is there to reduce muzzle blast and offensive noise first and foremost.

I've also grown weary of the heavy cans out there attached to the end of a lightweight AR15, drawing back to experiences with the KAC QD cans, my Ase Utra Jet CQB can that I had for a while in Europe, and other heavy alloy suppressors.

I went with brake attach. This suppressor is really doing exactly what I wanted.

To regulate back pressure, I'm using a Bootleg Adjustable Bolt Carrier, which has a 4-way position selector that is accessible through the ejection port when the bolt is in battery. There is no need to disassemble or field-strip the upper. Just use a small flat head driver, and rotate accordingly.

Testing 2 different factory loads so far suppressed, I got them both ejecting smoothly at 4 o'clock using the full suppressed position. This was with 90gr TNT and 120gr OTM, both loads from Federal in the American Eagle line.

To give an indication of back pressure, the gun has cycled 100% so far in low round counts with 123gr Hornady BTHP American Gunner. With the 90gr TNT unsuppressed, I think the Maxim PDW action spring is too stiff, so it short-stroked with that load.

As soon as I attached the suppressor, 90gr TNT ran like a raped ape on all 4 gas settings, as did 120gr OTM on position 4. I fully expect 120gr OTM to run unsuppressed as well since there is more back-pressure into the system with a longer 120gr bullet resisting being driven through the barrel, unlike the 90gr flat-based TNT which needs to be punted out with fast powder.

Unsuppressed, I'm getting an average mv of 2670fps with the 90 TNT (5rd sample).

Suppressed, I'm getting 2683fps (9rd sample).

With 120gr Federal OTM suppressed, I'm getting 2384fps (11rd sample).

Once I choked the gas selector to the fully suppressed position, I can no longer see telltale signs of brass soot coverage like when it was fully open.

For those looking to do SBR or pistol Grendel suppressed, hopefully this can save you some trouble.

 

[Srikaleak]

I'm planning on a 11.5" Grendel build paired with a 6.5 TBAC Ultra 9. Are the gas concerns so great I should get another can?

 

[LRRPF52]

I'm planning on a 11.5" Grendel build paired with a 6.5 TBAC Ultra 9. Are the gas concerns so great I should get another can?

It's just going to be really long mainly. I wouldn't go more than Ultra 7 for an 11.5" Grendel. Definitely make sure it's a 30 cal and not 6.5mm can for the gas gun. The Ultras are one of the best suppressors on the market for noise reduction, so you really get a lot of performance in a much shorter tube than you would expect.

As mine sits, the overall length measured from pivot pin to muzzle is shorter on this 12" Grendel/Ultra 5 than a 16" with A2 muzzle device. It's a very compact and handy package.

I basically wanted a do-all little blaster that could:

* Be maneuverable in the house for HD
* Handle well inside the cars and trucks
* Be effective at hunting medium game
* Be able to reach out at distance with high hit probability using high BC projectiles
* Have more energy at the muzzle than a 20" 5.56 NATO
* Have more energy at 400yds than a 24" .30-30 Win. has at 200yds
* Exceed AK and SKS external and terminal ballistics from a much shorter barrel
* AR15 frame and parts commonality
* Suppressed without excessive muzzle weight

This does all of that in droves. My first outing with it at 800yds resulted in repeated hits on a small buffalo sil at North Springs, with the lowest BC 123gr TGT bullet I know of. I haven't even played with 123gr Scenar or 130gr RDF yet.

 

[LRRPF52]

I expected to have problems with this even unsuppressed because I was bashing 4 major component systems together that haven't been tested before to my knowledge. Instead, it ran with very well-behaved cyclic rate out of the gate.

That component chain consists of:

Maxim PDW action spring and tiny buffer (2.9 oz) > Bootleg Adjustable BC > Group Buy Monster Bolt > Faxon Group Buy barrel

The Maxim Defense short action spring is actually much stronger than a standard carbine spring. You can feel it when you cycle the action. This seems to keep the bolt locked longer, while driving the return stroke of the cycle of operations with more positive force for feeding, chambering and locking.

This all worked very well with the CProducts 25rd mag, Elander 17rd mag, and Hornady 123gr BTHP AG (200rd cans at Sportsman's).

I was in uncharted territory personally with such a small RET, buffer, and action spring from the Maxim PDW, and had some concerns it wouldn't work, but it actually feels better than all the standard carbine RET/spring/buffer combinations I've built and tested in 6.5 Grendel, including 2.9 CAR, H1, and H2 buffer combos with 16" MLGS .076" ported barrels.

My initial 3 months with this set-up have exceeded my expectations, but the experiment will continue for about 3 years before I can really nail it all down and make definitive statements about it.

One area I wonder about is how the adjustable gas system will deal with carbon build-up over time, especially on a suppressed set-up. I don't really want to shoot this gun unsuppressed anymore because it is so pleasant to shoot with the Ultra 5 on there.

Unsuppressed, I didn't notice any real difference between it and a 16" Grendel as far as muzzle blast goes. Nothing like a 10.3" 5.56 NATO concussive blaster. It's just a very joyful shooting experience with the TBAC can on there.

 

[ccasanova]

Glad your wait is over. I’ve been waiting on your final report with your setup. Been shooting my 11.5 Grendel with my Omega and it’s much more enjoyable. Looks like the lightweight/short TBAC is a great match for the Grendel SBR. I have 3 of their rimfire cans which are incredibly light and quiet. I plan to use the Omega for 5.56AR duty, and get 5” and 9” TBACs to cover precision/distance and hunting.

 

[Strykervet]

I'm planning on a 11.5" Grendel build paired with a 6.5 TBAC Ultra 9. Are the gas concerns so great I should get another can?

The gas is coming from the fact it's a DI gas system --doesn't matter what you do, it's gonna get dirty. Pistons take care of that but I'm not a fan of 'em. A PRI gasbuster charging handle is a good idea though, I use 'em on all the rifles (it's just a good charging handle, period). Length like this around what, 18 inches? 19? I have a 5" too if I want it shorter and that'll make it more like 14". Without the can it's quite compact.

I've got KAC QDC, Saker, SDN6, 556SD, TBAC Ultras, etc., etc. and AR actions get dirty regardless of which one I use. Certain powders are worse than others, so finding a powder that performs and doesn't leave a ton of soot isn't a bad idea.

Here's mine, unfired, 11.5 Lilja bbl. and 9" Ultra:

 

[gedeon]

Supersonic crack aside, is it hearing safe with the 5 or 7? I try to double up my ear pro unsuppressed anything, but would like to be able to get to electronic in-ear only with a suppressor for shooter and anyone nearby. You can buy a lot of things, but not hearing once it is gone!

 

[Raffica762]

Man what a great build and write up ..love the Grendel

 

[LRRPF52]

Supersonic crack aside, is it hearing safe with the 5 or 7? I try to double up my ear pro unsuppressed anything, but would like to be able to get to electronic in-ear only with a suppressor for shooter and anyone nearby. You can buy a lot of things, but not hearing once it is gone!

I've only shot this one with Sordins on suppressed at a local range.

My first outings with it were unsuppressed at one of my Long Range courses for a private group.

I've shot the Ultra 5 on a .17 HMR before when on staff for Steel Safari in 2016, and it wasn't hearing safe with that combo. Felt like a lot of noise was coming from the ejection port since it's blowback.

At Steel Safari, someone was shooting a 20" Grendel with an Ultra 5 off to my right on the range by the main house when I didn't have ear pro on, and it was Hollywood quiet. I didn't feel anything, but I was a few lanes down.

 

[SLG]

Thats pretty sweet!

My grendel is a 16" full house custom from mstn, built a few years ago when there was not nearly as much choice. Had to source the lilja, source the bolt, etc...

What is the go to 12" upper setup today? Reliability being #1, and LR accuracy being very desirable.

 

[LRRPF52]

Thats pretty sweet!

My grendel is a 16" full house custom from mstn, built a few years ago when there was not nearly as much choice. Had to source the lilja, source the bolt, etc...

What is the go to 12" upper setup today? Reliability being #1, and LR accuracy being very desirable.

I only have a sample of 1 so I can't answer that exactly with the 12" guns, but I think we can apply a formula.

The barrel profile on this Faxon Group Buy barrel was spec'd with a really long, full OD shank.

It's .975" for 3" of length, then steps down to .700". It's heavier than most of the 18" barrels I have for sure...but it shoots.

Shorter barrels experience less whip for the same diameters compared to longer ones, so I think there is a good whip axis deflection advantage, with an obvious mv penalty.

I grabbed another group buy 12" barrel as soon as it was made known someone backed out on it. Based on what I'm seeing so far over the chrono and on-target at 800yds, I don't have any reservations about how precise this will be for shooting steel.

The reliability chain I've seen with this one sample includes the recoil system from Maxim, which is much more stout. I haven't heard of others experiencing issues with standard carbine buffers and springs though.

CLGS 12" Grendels that work well are using .068" gas ports and SAAMI chamber.

We did a more shallow rifling profile for the lands on these, so speed seems to be more like a 14.5" Grendel so far. Based on what I saw with the 120gr Federal OTM Match, I don't think I'll have any problems breaking 2400fps with 123gr target bullets from this 12" Grendel, maybe more.

I don't plan to try to push it into something it isn't though, and will focus more on how my cyclic rate is behaving. Since I already have better-than-expected performance at 800yds with the lowest BC 123gr TGT bullet I know of, it can only get better than that.

 

[SLG]

I worded my question poorly. I figured from your post that you went a route similar to the one you laid out above. It is clearly a very nice setup, but I am curious if anyone makes a complete upper that is good to go in th 11.5-12.5" range.

I would rather not build another one up, but if that is the only way to go, I think for my use, an Aero Precision upper with a BA barrel might be nice. Unless a lilja falls in my lap. I can't even find them on their site.

I would like it to be fairly light, given how i will use it.

 

[LRRPF52]

Barrel options right now for short pipes include:

AA 11" Lightweight (1.36lbs/21.76oz)
Ballistic Advantage 12.5" Hanson (22.3oz)
Faxon Gunner 12" (20.32oz)
Faxon Group Buy 12" 5REE (26.6oz)
LaRue SUURG 11.5" Complete Upper with muzzle brake core for slip-over TranQuilo suppressor
Palmetto State Armory 12" (Complete Uppers and pistol kits)
Precision Firearms 7.5"-14.5" Criterion, Lilja, Bartlein, Krieger

There are probably more that I'm just not thinking of off the top of my head.

 

[SLG]

Barrel options right now for short pipes include:

AA 11" Lightweight (1.36lbs/21.76oz)
Ballistic Advantage 12.5" Hanson (22.3oz)
Faxon Gunner 12" (20.32oz)
Faxon Group Buy 12" 5REE (26.6oz)
LaRue SUURG 11.5" Complete Upper with muzzle brake core for slip-over TranQuilo suppressor
Palmetto State Armory 12" (Complete Uppers and pistol kits)
Precision Firearms 7.5"-14.5" Criterion, Lilja, Bartlein, Krieger

There are probably more that I'm just not thinking of off the top of my head.

That compilation of weights is useful, thank you.

I was originally looking for a PF upper, as I have long been recommending them as a plug and play setup for precision 6.5G use. I have not found a shot 6.5G barreled upper though, or even a lone barrel. I should probably give them a call and see what can be done.

 

[TonyTheTiger]

McGowen will make you a short tube. $250 before options.