I was wondering if anyone else ran a Surefire warcomp on their precision ARs? I recently installed one on mine in preparation for my suppressor, and immediately noticed a loss in accuracy. The rifle had been shooting .4-.6 MOA before and now started shooting .8-1.0 MOA. I took it out twice with it mounted and got the same results. Today, I took it off and went to the range to shoot with a bare muzzle. Only brought 10 rounds and both groups were .4 and .5 again.

Looking at the warcomp, there appears to be a chamber where the holes are drilled. My guess is that one side of the chamber has a different pressure than the other due to the holes, potentially unbalancing the bullet slightly. That's just my guess though. I have had this issue with a similar comp in the past on another rifle, although open brakes and flash suppressors (AAC blackout) did not exhibit any accuracy loss.

I have no personal experience, but I know someone who had a bad experience with one of the Surefire "legacy" muzzle brakes, (but who later used them successfully) and I know of someone else that has suggested that the OPS-Inc style brakes (a very open design) can also affect accuracy at the very "precise" end of the spectrum.

I personally probably wouldn't be able to tell between 0.4 and 0.8, but at that (pretty darn good) level of accuracy I absolutely understand how a doubling of group size would be a problem.

I would think it has much more to do with harmonics than gas but thats just my opinion. anything you add to your barrel can change the harmonics, even the amount of torque you apply to tighten it can
make a difference.

That's possible. Harmonics are changing for sure since POI is changing. I just know the accuracy difference is noticeable.

Handloads or factory? How did you install it, to what torque value? Wes at MSTN has built a ton of hammers with the Warcomp, as well as EraThr3. My guess is a sensitive handload or slightly off installation.

Personally, I wouldn't use on a gun that's going to be shot prone for groups, as the compensating feature is asymmetric about port/starboard and if you're not loading the bipod properly (assuming you're shooting off one) then I could see the potential for a little shift in gun, either during firing or shifting your position in between shots. I'm less inclined to believe that, but I seem to always blame voodoo when shooting a gas gun.

Handloads. You may be on to something with the lateral compensation and the bipod. If it's pushing the rifle in a direction that it doesn't want to give due to the bipod, it could mess with things. I did verify with factory Black hills 77 and it was no better.

Here are targets from my last two trips. Left target was with the warcomp installed. Right target was with bare muzzle except at end of day, I screwed the warcomp on hand tight for the top left group. While the rifle isn't "inaccurate" with the warcomp, it's clearly more accurate without.

Hmm, so those are with BH 77gr, or the handloads? When you say the BH was no better did you shoot it with the Warcomp on and bare muzzle, or just with the Warcomp on?

I see you had it on at 15 ft*lbs, crank it up to 20-30, whatever times it. I know the standard is 15, but Surefire says 20-30 so maybe that will do something. I wouldn't really expect it, but it's worth trying.

It's been a minute since I opened the package for a Surefire muzzle device; does it come with chamfered washer and a bunch of thin washers to time it? For a used barrel I usually take a brass brush with solvent over the threads, wipe with solvent til clean, maybe degrease if I'm paranoid with acetone then IPA or just IPA, then apply anti-seize, work the device on and off the threads to coat both male and female then standard timing and torquing.

I will say your groups look like mine for a gas gun when I don't have a good position and I end up slightly muscling the rifle, so that could support the control difference effect theory with the Warcomp. And I mean a lot like mine because I use those same dots.

All hand loads. I shot the BH on a different day. I don't have the target but groups slightly worse than hand loads.

The warcomp did come with the chamfered washer and smaller ones.

I have since mounted a PA M4-72 and have been seeing good accuracy again. I can't mount the suppressor to it but I wasn't planning on shooting this rifle suppressed that often anyways.

Eta: Obligatory picture of rifle

Did you try the Black Hills with just the Warcomp or also with any other muzzle configuration so that you could determine a baseline for how your rifle shoots it? Black Hill commercial can be a little picky I've found with gas guns, compared to the actual brown box issue MK262, which has hammered in every AR I've shot it through, which is a statistically decent number.

I also lost my train of thought in my last response, this has been a particularly shitty week. When you installed the Warcomp you just used the flat skinny washers, right? You only use that chamfered spacer if the muzzle threads don't have a relief between the threads and the shoulder.

Have you seen any other reports of the Warcomp degrading accuracy?  I'm about a RCH away from pulling the SF3P off my 14.5" Noveske and twisting on a Warcomp.  If that went well I was going to do the same for the LPR, and then also stick one on the 16” Stealth.  Your results made me tap the brakes, so to speak.  



What adapter is that between the URX and the ball head?   Magpul?

I've been looking at the Manfrotto pistol grip with a Hejnar adapter so I can use the RRS Arca plates that mount to picatinny, Keymod, or Mlok forearms.

I have not. And it also depends on the level of accuracy of the rifle. I took the same warcomp and put it on a 18" Douglas barrel and it seems fine. The rifle pictured is one where I'm trying to keep the highest level of accuracy possible.

The adapter I'm using is the magpul. The Manfrotto ball head seems to be holding the rifle fine, although the 190proL tripod isn't quite stable enough.

What torque?

High torque can build up stress on the muzzle, causing loss of accuracy.

I prefer no torque when installing muzzle devices, and time them accordingly.

15 ft-lb and hand tight (less than 5).

Surefire recommends between 20 and 30. I agree that too much can cause accuracy loss.

My current muzzle device (M4-72) is tightened to 10 ft-lb and I'm getting excellent accuracy. I don't think the issue was the torque.