Installed Muzzle Brake Decreasing Accuracy...

[Boss334OP]

I recently installed a RWS Muzzle Brake on my Rem 700 AAC-SD and my groupings opened up. Without brake, accuracy was about .5 to .75 MOA. With brake, it has opened up to around 1.5 MOA. The brake has been shimmed to allow proper timing. Could this be the issue or is there something else I should be concerned with? I like the reduced recoil and look but I am much more interested in increasing accuracy. Any input is appreciated.
Thanks,
Nate

 

[jason bourne]

Re: Installed Muzzle Brake Decreasing Accuracy...

Are you using factory loads or hand loads?
The brake changes the harmonics of the barrel, and in some cases the muzzle velocity. this can cause a group to open or close up depending on the rifle and load. this is especially true if a load was worked up in a rifle without a brake on.

 

[gunshinestate]

Re: Installed Muzzle Brake Decreasing Accuracy...

Interested to know more. I have same setup and just had the brake installed/timed by AO here in town. Would like to know what loads you're using.

 

[roggom]

Re: Installed Muzzle Brake Decreasing Accuracy...

Try shooting from a sled, with the brake on and off. I run a RWS and it does reduce recoil rather effectively, but it can sure blast you in the face (especially at indoor ranges). Not saying to shoot from a sled all the time, just for troubleshooting purposes.

 

[Gray]

Re: Installed Muzzle Brake Decreasing Accuracy...

Every muzzle brake I have has changed the point of impact, but not opened up the groups.

 

[Field]

Re: Installed Muzzle Brake Decreasing Accuracy...

Try shooting with it off. That will tell you if it's something with the brake or if its something with the machine work/crown.

 

[Topstrap]

Re: Installed Muzzle Brake Decreasing Accuracy...

We can switch between a Ross and Harrells brake and have also put screwed a Compensator on and the group sizes are always the same. Between the two brakes and the Comp we tried all three shot to the same POI on my 260 rifle and LR pistol. I've not shot either one without a brake but do imagine it will affect POI but should not affect groups if installed correctly. Like roggom mentioned, sometimes there is quite a blast from the brake and even though you don't think it bothers you some shooters have to get used to it. The blast is quite noticable on my 15" LR pistol and takes some by surprise, usually their next shot isn't even close unless they are quite a seasoned shooter.

Topstrap

 

[MJY65]

Re: Installed Muzzle Brake Decreasing Accuracy...

A friend of mine just had a similar problem. A previously accurate rifle started throwing fliers. It turned out that the gunsmith had threaded the barrel a bit off and he was getting bullet strikes on the inside of the brake every 3-5 rounds. Barrel cut and re-crowned. Accuracy restored.

 

[hdbiker1]

Re: Installed Muzzle Brake Decreasing Accuracy...

I had an AAC-SD that I put an Ops Inc brake on and the groups opened up considerably. Replaced with the AAC Blackout and groups shrank by 30% on average.

 

[Boss334OP]

Re: Installed Muzzle Brake Decreasing Accuracy...

Factory loads only: FGMM 175's and 168's. Both had proven to be quite accurate out of this rifle.
Accuracy returned after removing brake. Looked for any signs of misalignment and didn't find any. There was a decent amount of carbon build up on the crown though. <Problem???
I find the rifle is more pleasurable to shoot with brake on so I am sure I am not flinching or jerking etc. Also, the rifle was sandbagged and all other fundamentals of marksmanship were followed so I am 99% certain the accuracy drop is not due to operator error.
Maybe I should try some different loads and see what happens?
All input appreciated.

 

[Straight Shooter]

Re: Installed Muzzle Brake Decreasing Accuracy...

Was you barrel threaded for this brake or did you put a brake on existing threads? We have run into a bit of runout with Ross's brakes. They are still a value but we just order them as blanks and bore them once mounted to get them lined up right.

The other thing is how tight did it take to get it to clock? If the brake is too tight it will constrict the bore and will cause point of impact changes and can affect accuracy.

 

[Boss334OP]

Re: Installed Muzzle Brake Decreasing Accuracy...

The brake was put onto pre-existing threads. But I did let Ross know that it was for a Rem 700 AAC-SD model prior to ordering.
I do have the brake locked down really tight... Most likely tighter than it should be. How likely is it that re-shimming my timing and loosening will improve accuracy? Or is this something that I might have to actually have smithed? Thanks.

 

[Straight Shooter]

Re: Installed Muzzle Brake Decreasing Accuracy...

Reshimming and loosening may help. Alignment needs checked too.

For future reference I prefer to dial in the bore and cut my own threads for brake installations. Then bore the brake clearance perfectly concentric with the bore.

Buying or having a barrel prethreaded is a bad deal unless it's a close quarters battle accuracy application where you are switching things on the end of the barrel for mission specific accessories. For precision accuracy the tollerances are much tighter than just buying premade bolt on stuff.

 

[culater]

Re: Installed Muzzle Brake Decreasing Accuracy...

Its time to learn to reload your own

 

[Furyataurus]

Re: Installed Muzzle Brake Decreasing Accuracy...

Try another brand of brake.

 

[Mike0341]

Re: Installed Muzzle Brake Decreasing Accuracy...

i never shot my rifle without the brake so i cant be of much help. my cousin however has the same rifle and when he installed his JP enterprise brake he only noticed a change in poi.

 

[BillyGoatMachine]

Re: Installed Muzzle Brake Decreasing Accuracy...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MJY65</div><div class="ubbcode-body">A friend of mine just had a similar problem. A previously accurate rifle started throwing fliers. It turned out that the gunsmith had threaded the barrel a bit off and he was getting bullet strikes on the inside of the brake every 3-5 rounds. Barrel cut and re-crowned. Accuracy restored. </div></div>

This happened to me as well.

 

[ballistic1]

Re: Installed Muzzle Brake Decreasing Accuracy...

You owe it to yourself to try a few other brakes and post results.

As you have stated, accuracy was good before the brake installation, and
accuracy is good again once the brake is removed.

Perhaps your rifle will shoot great accuracy when trying another brand.

It could be that the mass of the brake alters your bbls harmonics, thus
affecting how it shoots the ammo that you normally group well.

I know of a 243 that shot everything well, then a brake was added, and it
only liked 55 gr afterward. Fickle nature of the beast.

Please post your follow up results on this matter.. thanks

 

[ml4x4]

You're not alone, I had exact same issue with exact same rifle.
700 AACSD set in a manners T2A stock, action trued, factory barrel threads, etc.
.5 minute groups prior to AAC Blackout install, opened up to about 1.5 after. Removed brake, shot 4 5-Shot groups that closed back up to .5. Results measured with both hand loads as well as factory FED GMM and Black Hills 175/178 Gr.
No sign of rounds marking the brake what so ever.
Will probably go with SF and see what happens next.

 

[vtb]

1. how your brake was installed? via crush washer? if so - change it to shims.
2. Try change a brake to SF, 762-211C.

 

[Frank Green]

You can install/tighten a muzzle brake to tight onto the barrel. When this happens you deform/distort the bore right at the muzzle end/crown of the barrel. Upsetting the bore right here will take your accuracy and throw it out the window. I install brakes with loctite. You don't have to pretend your a German weight lifter and putting a torque wrench onto the brake. Just snug it up and let the loctite set up. The loctite will keep the brake from vibrating loose during shooting which leads me to the next point.

If the brake is loose at all it will vibrate and cause harmonic issues with the barrel. Make sure it is not loose.

Another thing to check is the bore of the brake opened up for proper clearance? If not the bullet could be hitting the brake on the way out and this will cause accuracy issues as well.

Also check the muzzle threads and or brake for to much run out. This will cause alignment issues with the brake/barrel assembly.

Yes a muzzle brake can possibly cause harmonic issues and effect accuracy but in my opinion more often than not if the barrel shoots fine with out the brake it's not with the barrel. It's with the brake set up/installation somewhere that is giving you grief.

This is very common with AR15 match service rifles and M14 match rifles where the flashider and the castle nut on the M14 is put on to tight and it distorts the bore. It throws the accuracy right out the window.

Later, Frank
Bartlein Barrels

 

[JByrd]

Straight from the man ^^^^

Ps as a side note, on a timed brake i like to have mine clocked to a snug hand tight.jered at apa timed all my brakes this way and i never ever ever had one back off. It also works well if you run suppressors. No tools necessary. Simply take brake off, supp. goes on.

Also, i only clean barrels every 500 rds or so"im not saying you do that,do what ya want" the kreigers and bartlein barrels are super slick and havent required it. >>>BUT<<< your brake/crown will. I soak brake in highly concentrated lemishine/water concentration for 24 hrs and crud rinses off. I will mix lemi shine and water on greenscrub side of kitchen sponge overnite and leave gun resting crown down on the sponge in a bowl. In the morn i will give the gun a spin on the sponge and crown is sparkly clean GTG. and ocassionally ive had to hone the bore of brake to remove gas etch burs using brass rod split partially with fine grit sand paper spun by cordless. But thats only been one brake and it totally restored it back to as new drillin again"centershot four port" awesome brakes,very effective.

Ok book over these have been my expierences with brakes/accuracy

 

[ml4x4]

I installed mine myself with the supplied shim kit. I wanted it as close to flush with the barrel as possible so I used the best shim/torque ratio I could without over tightening to accomplish this goal. I tightened it to snug with the right shim combo to allow it's proper verticle alignment. Groups opened up.
Took it to the shop, brake re-installed by them with shims but further out this time because of the advice that the threads appeared that they ran out possibly causing a slight shift in alignment. Still not shooting .5 moa like before. I really need another trip to carefully shoot on the bench as I've only run about 5-10 rounds prone not under ideal conditions but even at that I wasn't very happy with the groups. I'll report back after I get a solid range trip in.

 

[JByrd]

Another thing to remember " i see you live in ga" , if your shooting groups or zeroing rifle. Do it at or before sun up or right at sunset. Mirage of summer will have you chaseing your tail.

 

[agbm]

Rem 700 AAC SD with JP recoil elininator with nut , It 1/4 MOA with Fed 175 GMM ammo if i do my part.

 

[ml4x4]

Just ran back across this and I haven't had a chance to get back out with it to test the grouping with the AAC brake. Procovert45, thanks for the heads up, I've been out in the GA mirage and it certainly can make things really difficult. Just for seeing how the gun groups with the brake installed, I was shooting under 300. This gun has shot .25 moa out to 600 before so I know it's capable. Another solid member here has helped me all the way through this build so next time we're out I'll try to remember to report back how it went.

 

[Toddmonty]

I had the same setup & installed a CORE break & it reduced group size & recoil, but it was sure louder!!!!

It wasn't cheap by any means, but it works great!!!