I got a PWS muzzle brake and put it on my remington 700 5r 308 with 20" barrel. Usually I can shoot a 5 shot group at 100 yards with my CAN on it (no brake) and I can cover the group with a dime. I installed the PWS brake and it opened my group to about 1 to 1-1/4 inches at 100 yards. Anyone know why it might do that? I used my same reloads as I always do. Thanks in advance.
- Thread starter Bullseyelr
- Start date
Change in harmonics of the barrel do to change in weight at muzzle.
Your best bet is to get a thread protector that is the same weight . Re zero and it should stay close to the same .
Other wise i would think the diff in gas exspultion from barrel do to break .
My thoughts i may be wrong .
Sent from my SM-T310 using Tapatalk 2
Your best bet is to get a thread protector that is the same weight . Re zero and it should stay close to the same .
Other wise i would think the diff in gas exspultion from barrel do to break .
My thoughts i may be wrong .
Sent from my SM-T310 using Tapatalk 2
Unless there is something mechanical, I would surmise that the brake has changed the harmonics of the barrel.
Paul
Going from a 3/8" (assuming both with and without the can) gun to a 1-1/4" gun with the brake, I'm betting the brake bore is not concentric and you are rubbing it. That big of an accuracy decline is more than harmonics, in my opinion.
Center line of the brake has to match center line of the bore, if not groups open up. I am no machinist but have built my own brake for my 300wm, POA/POI does not change with the brake on or off. The brake is 1.45" in diameter and 2.5" long, with a 0.318 exit hole, on a 26" #7 taper. Cans are the same way, everything in alinement and all that changes is up, for droop if any.
I had a vias break installed on my custom build by my smith and had no POI or grouping change either with the break or with thread protector on. I may just be lucky but my smith told me that it shouldn't change anything unless I chopped the barrel length down.
You may try another ladder test and see if in fact it's just barrel harmonics. If that doesn't help, take it to a smith a let him take look and see if it's a center line issue with the break.
You may try another ladder test and see if in fact it's just barrel harmonics. If that doesn't help, take it to a smith a let him take look and see if it's a center line issue with the break.
I've seen the same thing with a lot of factory barrels, with the can on they would shoot like a custom barrel with about any load. But if you took the can off they would become sensitive to what load they would shoot well.
Time to check the brake for concentricity with the bore, not the OD of the bbl. I like to have my brakes on my guns cut such that the first hole in the brake is flush with the OD of the barrel or slightly behind. Mostly that requires shims behind the brake unless your smith installed the brake and threaded the barrel. Second thing I like to do is to bore the brake and, if necessary, the baffles, 0.030 over the bore of the bbl, so, for 308, I drill the hole 0.338 diameter or as close a drill as I can find. Too lazy at this time to check drill sizes. I then cut a light chamfer, 0.030" at 11 degrees on the end of the hole. I don't know that it helps at all but just looks right to me.
In my experience, limited though it is, a muzzle brake has tended to tighten groups rather than open them up. My LWRC REPR was a 1" gun till I put a brake on it and tamed recoil. Now I am under 0.75 with a best group so far of 0.47. Even my 6.5 Creedmoor now wears a brake and I am just learning how to really shoot that rifle and playing with different factory loads. Best so far is in the 0.37 range c-c for 5 shots with an average of around 0.625. It ain't the gun, cest moi.
In my experience, limited though it is, a muzzle brake has tended to tighten groups rather than open them up. My LWRC REPR was a 1" gun till I put a brake on it and tamed recoil. Now I am under 0.75 with a best group so far of 0.47. Even my 6.5 Creedmoor now wears a brake and I am just learning how to really shoot that rifle and playing with different factory loads. Best so far is in the 0.37 range c-c for 5 shots with an average of around 0.625. It ain't the gun, cest moi.
here is an experience that may be relevant.
A close buddy of mind got a GAP gun in 300 WM. He took it to another "gunsmith" who installed a YHM brake/adapter for a YHM titanium suppressor with a crush washer. As a side note, the GAP guys are not fans of the YHM suppressors. In any case, we could not get that gun to shoot for shit with any load after that YHM brake was affixed, and we tried a dozen loads/bullets, etc. In the process, over 50-100 rounds of different handloads varying bullets, powders and charges, we did discover that GAP had installed the wrong rings (weaver rings on a Picatinny base), one was loose, (we tightened it, then later swapped out to Badger picatinny rings) and the base also came lose (jeez!) and we tightened that. Even after we fixed the problems, this brand new GAP gun was still like a 1-1.5 MOA gun with handloads, match bullets, multiple experienced shooters.
After sending it back to GAP, and THEN to YHM, eventually it was rectified (now it's a 1/2 MOA gun as guaranteed), but the lesson for this particular gun was clear. The YHM brake screwed the accuracy all to hell.
Your brake could certainly be the problem. We wish we had unscrewed that damned brake much earlier in our troubleshooting. That would have saved us hundreds of dollars in ammo and countless hours in changing scopes and loads (heck, we took a scope off my .25MOA 40-X and put it on this gun during our troubleshooting!), and all the other tribulations we went through to get the gun back to shooting how it should have (and did) when it left GAP.
A close buddy of mind got a GAP gun in 300 WM. He took it to another "gunsmith" who installed a YHM brake/adapter for a YHM titanium suppressor with a crush washer. As a side note, the GAP guys are not fans of the YHM suppressors. In any case, we could not get that gun to shoot for shit with any load after that YHM brake was affixed, and we tried a dozen loads/bullets, etc. In the process, over 50-100 rounds of different handloads varying bullets, powders and charges, we did discover that GAP had installed the wrong rings (weaver rings on a Picatinny base), one was loose, (we tightened it, then later swapped out to Badger picatinny rings) and the base also came lose (jeez!) and we tightened that. Even after we fixed the problems, this brand new GAP gun was still like a 1-1.5 MOA gun with handloads, match bullets, multiple experienced shooters.
After sending it back to GAP, and THEN to YHM, eventually it was rectified (now it's a 1/2 MOA gun as guaranteed), but the lesson for this particular gun was clear. The YHM brake screwed the accuracy all to hell.
Your brake could certainly be the problem. We wish we had unscrewed that damned brake much earlier in our troubleshooting. That would have saved us hundreds of dollars in ammo and countless hours in changing scopes and loads (heck, we took a scope off my .25MOA 40-X and put it on this gun during our troubleshooting!), and all the other tribulations we went through to get the gun back to shooting how it should have (and did) when it left GAP.
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fpni start over with your reloads until you find the sweet spot again. 22lr benchrest shooters put a "tuner" on their barrels to change the harmonics. it is about changing the way the barrel vibrates just as the bullet leaves the barrel.
Nothing weird about a small POI shift.
Adding a brake changes harmonics.
If after load development the rifle still will not shoot well with the brake on, then tell your smith to try again with the brake install.
Adding a brake changes harmonics.
If after load development the rifle still will not shoot well with the brake on, then tell your smith to try again with the brake install.
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