12" 6.5 Grendel Suppressed, 6-year Update

[Rocketvapor]

LRRPF52, I like your build, and logic in your selection process.
Really shows why my 5.56 pistol was just a "see, I can do it" effort
Don't want to spare the dollars for some of the features you opted for but that is one well thought out build.

+1

 

[snarkscarbine]

You’ve got me inspired. Parts should have all trickled in by Monday for my 12.5” pistol. ??

 

[Srikaleak]

Here's my first AR build. It's a 12in 6.5 Grendel using mostly JP parts, Green Mountain barrel, LMT PDW stock. Will be putting it through its paces but on first outing it shot one-hole 5 shot groups at 25yds.

 

[LRRPF52]

View attachment 6999155Here's my first AR build. It's a 12in 6.5 Grendel using mostly JP parts, Green Mountain barrel, LMT PDW stock. Will be putting it through its paces but on first outing it shot one-hole 5 shot groups at 25yds.

Dude, that's sick. That thing is tiny with the LMT PDW stock.

I've since acquired a Precision Firearms 10.5" Criterion 6.5 Grendel barrel for an even more compact build, just to see what it will do also.

The numbers with the 130gr Nosler RDF are unbelievable even using G7 drag model (which is what you should be using).

At 6600ft elevation, it looks like supersonic reach to 1300yds at 2230fps muzzle velocity.

Right now the Federal 120gr AE is clocking 2400fps from the 12" Suppressed, so I'm thinking the 130gr RDF will easily get to 2300fps, with nodes in the 2250-2300fpr range. There's a guy getting some pretty impressive speeds using Power Pro Varmint under the 130gr RDF, and bughole groups from a Wilson Combat 20" Grendel barreled AR15. A lot of people who tried to get the 130gr RDF to shoot had trouble getting it to group well, but I suspect many of them were using conventional freebore chambers vs a SAAMI compound throat true Grendel chamber.

I have an ADM ambi UIC lower receiver waiting to be completed. Gotta build my new armory first.

 

[Bully]

Dude, that's sick. That thing is tiny with the LMT PDW stock.

I've since acquired a Precision Firearms 10.5" Criterion 6.5 Grendel barrel for an even more compact build, just to see what it will do also.

The numbers with the 130gr Nosler RDF are unbelievable even using G7 drag model (which is what you should be using).

At 6600ft elevation, it looks like supersonic reach to 1300yds at 2230fps muzzle velocity.

Right now the Federal 120gr AE is clocking 2400fps from the 12" Suppressed, so I'm thinking the 130gr RDF will easily get to 2300fps, with nodes in the 2250-2300fpr range. There's a guy getting some pretty impressive speeds using Power Pro Varmint under the 130gr RDF, and bughole groups from a Wilson Combat 20" Grendel barreled AR15. A lot of people who tried to get the 130gr RDF to shoot had trouble getting it to group well, but I suspect many of them were using conventional freebore chambers vs a SAAMI compound throat true Grendel chamber.

I have an ADM ambi UIC lower receiver waiting to be completed. Gotta build my new armory first.

Any further movement or development on this? I have a 12.5" barrel on the way and will start trying to uncover my components to see what I have to load.
I'm in Texas and I believe much lower than you so I will for sure be taking that in to account as well.
Thanks for any help.

 

[LRRPF52]

I still have not hand-loaded for the 12” Grendel yet, nor have I even started the 10.5” build. I have enough parts for multiple options for each major sub assembly area for the 10.5”, so it has just been a matter of time. I’m thinking blast can/linear comp before I decide on what suppressor will go on the 10.5”.

I’ve shot only factory ammo through my 12” and the other 12” I built. The other one has been run with a 107gr SMK/8208XBR load at 2440fps.

I’ve shot 123gr Hornady American Gunner (came in 200rd ammo plastic boxes from Sportsman’s), 123gr ELD-M, 90gr TNT, 120gr Federal AE OTM. I tried the Amend2 10rd polymer mags the last 2 outings, with no malfs of any kind. Left them loaded in the rifle case for months fully compressed just to see what would happen.

My build process has about 50 extra steps compared to a parts bash build approach, so I set myself up for success for reliable feeding and maximum mechanical accuracy potential from the blaster as possible.

 

[LRRPF52]

So this is a 6-year update to the 12” Grendel, which has been shot fairly-regularly since I started the thread in 2018.

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.

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.

Yesterday, 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 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 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.

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. 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 RDFs.

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

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.

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. 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.

 

[HotRod68Camaro]

EDIT: I should have just put 5 minutes in google. i actually found a post by you on another forum that answered my question.

 

[LRRPF52]

One thing that has changed my mind over the past 2 events shooting the 110gr PPU is regarding 6mm AR.

I have always had a plan to build a 6mm AR or AR Turbo, which would be easier to do now with a 6mm ARC with factory ammo support. I have also spent many years spotting or RO’ing for people shooting 6 Dasher/6 XC/6x47/.243, etc., so I know what 6mm sounds like when it hits steel (not impressive as you get out to 650-700yds and beyond). It’s very easy to connect on steel with 6mm, but you don’t get that loud “whack” that you do from 123gr 6.5mm and above. I noticed this when I went through Canyon West at Steel Safari after the first day of RO’ing. Most competitive guys (ones who had a chance at placing) were shooting 6 Dasher, 6x47, .243 AI, some type of hot 6mm, so I had it fresh in my mind what 6mm sounded like on the steel. They were all running 25-26” barrels too, pushing the speed as much as possible.

I took my little 17.6” Grendel through the canyon from position-to-position since I knew where all the targets were, and just worked the targets for fun. I noticed that the 123gr A-MAX sounded like it was hitting harder, and it was easy for me to connect. I can show you the numbers where the 6mms are all better on paper, but they sound anemic at distance.

Shooting 107gr and 110gr 6.5mm, even at 400yds, it isn’t that loud on the steel, and only gets quieter of course with distance. 123gr ELD-M, A-MAX, Scenar, and SMK hit the steel with more authority, almost sounding like a 168gr SMK .308”.

Basically, if I want 6mm on-target experience, I can get that already with 6.5 Grendel with 107gr SMK, 108gr Scenar, and 110gr PPU (“cheap”). The BC isn’t there, but I just made a bunch of 1st-round hits at the maximum distances at one of the coolest ranges I shoot, including 900yds, with a freaking 12” AR. The lower weight bullets just don’t do it for me on steel, which means .224 Valkyrie and anything 6mm are going to sound weak no matter what we do to them. Hit probability is higher due to BC, but the audible metrics just aren’t there.

The 130gr RDF is going to impact even louder than any 123gr or 129gr. The 130gr Sierra Game King with its huge meplat hits really hard and loud, but its BC is way too low.