Building the rifle Larue won’t sell you – Part 2


Part 1 Here.

Previously I established how there is the demand for a heavier barreled Larue PredatAR rifle. For someone starting new, the Larue Ultimate Upper would probably be the better choice as they could buy it what ever barrel they want. But that isn’t what I want.

I took inventory of what I had on hand:

16 Inch Larue Barrel with matching bolt carrier group (from the UU upper I had)
Magpul CTR stock
New A2 grip
Surefire Flash hider, and Surefire Muzzle Break. At the time I took this photo, I was unsure what I would use.
Geissele SSA trigger. My favorite trigger out there.

So, I needed a PredatAR upper. I had been looking for one for a while, but people tended to want to see the upper for about the same price you could pick up an entire rifle. After some time, I found a great deal on a donor rifle.

Came with all the accessories
The PredatAR is a great rifle as is, but we can make it better.

Let us start with the simple tweaks.

The PredatAR comes with these little proprietary grippy hand guard covers. I will start by removing all of them as I prefer them off.

With them off, you can see how there is a raised rib on the PredatAR handguard. This rib is what, to me, gives it a better profile for handling. Note how the threaded holes have helicoil style inserts. I am glad I am not the guy who has to install all those inserts.

Just how I like it.

Now to focus on the lower. I pulled off most of the parts. I was going to clean the inside of the trigger pocket but I found the previous owner had already done so.

I installed the SSA trigger (Later I decided I’d run a MBT in this Larue lower. I switched that out the following day).

I have this Arms Unlimited knockoff of a Norgon ambi-catch. Not only is the finish and exterior profile inferior to the Norgon, it also binds in a lower. I had thought that maybe the previous lower I had it in was out of spec, but when I found it was binding in the Larue lower, I also tried a Colt and it did not want to play nice with any of them. I think it might be because of how much cant there is in the body of the catch. Note how it tilts inwards instead of being perpendicular to the threaded shaft.

I was also disappointed to find the receiver extension was crooked. Sometime down the road, if I keep the Larue lower, I’ll replace that end plate with one with a QD socket and straighten the tube.

Throwing on the A2 grip and CTR gives the rifle ergonomics that better fit me.

The PredatAR has a chromed bolt carrier. I will use that carrier with the matching bolt for the barrel I am using. I’m going to sell off the old PredatAR barrel and parts. I’ll including the matching bolt with that barrel.

The handguard is held on to the upper by 4 bolts, with Torx heads.

This barrel nut is taken on and off by a 1 1/4 inch wrench. The barrel nut was very lightly torqued. Felt like I could have taken it off with out a wrench.

I decided I would use the newer PredatOBR/UU barrel nut when I reassembled this upper. The wrench for that style barrel nut is pictured on the right. I would end up regretting this choice.

Damnit Mark Larue!
Turns out the newer style barrel nut is longer than a PredatAR nut.
I had to pull the barrel nut off the PredatAR barrel.
I used my torque wrench when reinstalling the set screws on my barrel.
Surefire muzzle devices need to be timed. It can be an annoying process.
Despite needing to be timed, installing the Surefire Muzzle Break was pretty quick and easy.

I ended up installing the Surefire MB556K muzzle break. This has a history of use in both competition and combat. It has been tested and shown to reduce recoil up to 58%, and it double as a mount for the Surefire silencers I have.

I end up with a little heavier rifle, but not one unwieldy or awkward. This would be just as functional with a red dot for rapid fire up close as it would high magnification for shooting tight groups.

I look forward to putting it to good use.


  1. You do know that all AR upper and lower receivers are practically identical no matter the name on it. 90% of them come for 6 major Forge Companies of AR 80% lowers and uppers and are finished by the gun maker to MilSpec. Their are another dozen or so small er Forge Companies. The name and cosmetic finishes are the only difference. Colt is the exception, they forge and finish all their uppers and lowers.
    Anderson Manufacturing uses Cerro Forge lowers. All my homebuilt ARs use Cerro Forge 80% lowers except for my AR10 which has a 80% Polymer80 lower.
    LaRue lowers are made from a SMOS Billet. I see no advantage to paying a premium for the name on the lower receiver since they all must meet the specifications for the part.

    • A couple of notes.
      Larue hasn’t used SMOS lowers for some years now. You can find pictures of Larue Tactical making them in house.
      For years now, I, like many others, repeated the saying, “A lower is a lower is a lower.” Unfortunately that isn’t true. I’ve had lowers that wouldn’t drop mags free. I had a lower with the mag well had sharp edges. That same lower was out of spec in the take down pin location. There are far too many lowers out there that are inferior products.
      Still I agree with you, Larue lowers command a premium that I don’t think they deserve. I sold the previous Larue lowers I had for $500 each(far more than I paid), and people didn’t hesitate to pay that price for them. I may hold on to this one as I got a pretty good deal on it.
      I had to buy the entire rifle as Larue won’t tell a PredatAR upper by it self.


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