Muzzle brake issue?

[6.5grendel]

I bought a new Criterion prefit for a savage from NSS about a year ago. I wanted to get the barrel threaded for a muzzle brake but I wanted to make sure it shot decent before spending the money to get it threaded. I went ahead and put the barrel on and with a little load work up I had two different loads that shot .5 moa. I then took the barrel off and gave it to my gunsmith along with the brake that I bought. The muzzle brake was already bored out for 6.5 caliber. When I got the barrel back I put it back on and did load work up again and could hardly get it to shoot better than .75 moa and that wasn't even consistant after loading more to verify accuracy. This week I finally took the brake off and loaded 10 of a load that it shot .5 moa before the brake. I shot them at 100 yds and the 10 shot group measured .52 inch and was 4.25 inches lower than the poi with the brake on. Has anyone else had this happen? What would be the best way to determine if the issue is with the muzzle threads or the brake itself? Or is it possible that nothing is wrong?

 

[Dusty Stevens]

Its a muzzle weight. Work up a load

 

[swd]

Nothing is wrong, you just changed the barrel harmonics by adding weight to the muzzle. Group and POI can be greatly affected. Like Dusty said, work up a load again.

 

[6.5grendel]

I did load work up again with 2 different powders after I got the muzzle brake put on and the best groups I could get were around .75 moa. Most groups were over 1 moa. They weren't consistent .75 moa groups either when I went back out to verify those loads and get velocitys. The groups would vary between each 4 shot group of those best loads. It's a 260 rem and I tried h4350 and h4831sc with 142smk. When I did load workup before the muzzle brake with h4831sc there wasn't a single group over 1 moa. That was 4 shot groups and testing from 44gr to 47gr and the groups were very consistant after initial load workup. Is it possible that I just need to switch to a different bullet? I've tried different powders and primers but have stuck with the same bullet.

 

[Bill K]

As mentioned, you will have to work up another load or two, and that can mean different powder, primer and bullet/s, to see what the rifle with the brake on likes. ( almost forgot, did you try different setting depths, with that same bullet ?)

 

[Dusty Stevens]

You could have a faulty new muzzle brake and or installation. If the barrel isnt dialed in like a chamber and the brake bored after installation it will cause all kinds of issues as well

 

[6.5grendel]

I did not try different seating depths yet or different bullets. I'll try that and see if I can get it to come together. What really had me thinking something was wrong is that there is over 4 inches difference in point of impact at 100 yds between the brake and no brake. Is that normal? I have other barrels with brakes on them and the most they have is about 1.5 inches difference in poi with the brake removed. I looked for any indication of the bullet striking the muzzle brake but didn't visually see anything obvious. I didn't know if it would be possible to send the barrel to a smith to have the bore of the brake checked in relation to the barrel bore. And if it wasn't true with the barrel bore would it be possible to bore the brake out a little oversized just enough to get it trued with the barrel bore?

 

[coldboreshot]

I hate to bring up this point but I would have the muzzle inspected at the bore. If anything altered the fine edge that is expected of the muzzle/bore, it could definitely alter the accuracy. This is in no way a belittlement of your gunsmith but accidents/incidents do happen from time to time.

 

[coldboreshot]

Worst case, a minor re-crowning would resolve the issue, if that were the case.

 

[carlsbad]

The muzzle brake threads must be coaxial with the bore. I'm guessing your smith didn't do this alignment and the brake is deflecting the bullet.

I like to buy brakes small, thread them on coaxial with the bore, then bore the muzzle brake in place to ensure it does not deflect the bullet.

Just to be clear, I"m not saying it is hitting the bullet. It is deflecting it with unbalanced pressures as the bullet passes through the brake.

 

[Dusty Stevens]

^ thats what i was getting at.

 

[tobnpr]

Usually a brake will affect poi, but not accuracy provided no defect in the brake or installation.

You should ask the smith how he set up to cut the threads. It can be correctly done both through the spindle or between centers but it cannot be done by simply cutting the OD, the bore is often not concentric to the outside of the barrel.

Could also be a poor brake design. Is it a quality, name rand brake? Doesn't need to be expensive, but beware of fleabay...

Could also be your barrel doesn't like the change in harmonics it's causing.