I'll try to make this short. I added a clamp-on muzzle brake to my RRA heavy bbl varmint gun. Before muzzle brake, rifle shot consistent 1/2 MOA groups. I noticed a gradual reduction in accuracy over the next 500 rounds to where I thought my bbl was wearing out. Bbl cleanliness good through life of bbl. Total 1500 rounds through 223 Wylde bbl. Bore scope indicated nothing wrong with lands and grooves to indicate wear using the Teslong 45 degree mirror (90 degree view angle). However, when the Teslong passed through the crown, I noticed a fuzziness at the crown. I changed to the 25 degree mirror on the Teslong, As I approached the crown, I could see very deep channels leading to the crown. Those channels were not visible with the 90 view. My bbl had a recessed crown. The brake fit tightly and squarely to the muzzle. I have come to the conclusion that the addition of the brake was causing gas-cutting on the crown. I pulled the brake off and re-crowned the muzzle with a target crown. The gun is now back to shooting 1/2 MOA. I highly recommend anyone using a clamp-on muzzle brake examine your crown with a borescope using an angle other than 90 degree view. Sorry, no pics.
Gunsmithing Muzzle brake ruins muzzle crown
- Thread starter Old Fart 2
- Start date
I'm not so sure it's whatever you were seeing on the crown is related to the accuracy issue; I've never heard of "gas cutting" from a brake or any muzzle device and don't see how it is even possible- please educate me with documentation?
That said, brakes absolutely affect barrel harmonics and the heavier weight of a clamp-on may have made it more of an issue. Barrel harmonics are still the great unknown, impossible to predict whether changes will be beneficial or detrimental and to what extent.
Brakes and suppressors will commonly shift POI and usually will not affect accuracy, but it does happen. It's also possible that the brake itself is of poor design or defective and was improperly venting the gases pushing the base of the bullet off-center (obviously not much or you'd have had a baffle strike).
I've had a Witt clamp-on on one of the first rifles I built about 15 years ago (7-08) and it's an absolute tack driver.
That said, brakes absolutely affect barrel harmonics and the heavier weight of a clamp-on may have made it more of an issue. Barrel harmonics are still the great unknown, impossible to predict whether changes will be beneficial or detrimental and to what extent.
Brakes and suppressors will commonly shift POI and usually will not affect accuracy, but it does happen. It's also possible that the brake itself is of poor design or defective and was improperly venting the gases pushing the base of the bullet off-center (obviously not much or you'd have had a baffle strike).
I've had a Witt clamp-on on one of the first rifles I built about 15 years ago (7-08) and it's an absolute tack driver.
I'll say it, I'm skeptical. I've seen barrels with a muzzle device that'd have a crown get caked up with carbon, I've seen corrosion too, but I can't say that I've seen, experienced, or heard of a muzzle device causing any kind of gas cutting at the crown in so few rounds. You said that you removed the brake, re-crowned the muzzle and now it's back to its old self again shooting 1/2 MOA. Does that mean you shot the second 1/2 MOA group without the brake after the crown job? If that's the case, isn't it possible that the muzzle just had some carbon fouling on it and it didn't like having a clamp on device at the end?
I'm not saying that you didn't see a UFO but without pictures this largely becomes conjecture. It is a cautionary tale in muzzle devices though.
I'm not saying that you didn't see a UFO but without pictures this largely becomes conjecture. It is a cautionary tale in muzzle devices though.
There is a well respected barrel maker that cut a barrel blank with a hacksaw to evaluate velocity changes. No crown at all. Cuts were left "as is". Groups were still very good.
I believe @Frank Green can fill in some blanks here.
Get it...blanks! Barrel blanks!! Get it?
I believe @Frank Green can fill in some blanks here.
Get it...blanks! Barrel blanks!! Get it?
I'm sorry I don't have pics nor proof that poor accuracy was caused by gas cutting. What I do know is the gun was very accurate before and after installing my brake. So it wasn't a quick drop off in accuracy but gradual. To bring accuracy back took re-crowning the bbl. That is more than enough evidence for me that my crown got messed up within 500 rounds. I purposely didn't mention the manufacturer of my brake ... it is a Witt. I emailed them and they got back to me saying they had never heard of this. However, they told me they would talk to their engineer and get back to me which they never did.
I don't think all clamp-on Witts do this and that it might be just a unique combination of the crown design on my gun (recessed) and the Witt. It definitely creates a chamber just forward of the crown as the Witt is also recessed from the mounting surface.
I do know what gas cutting looks like. The cuts were spiraled at an angle matching the rifling. This was not crown damage due cleaning brushes. Again, I could only see the cutting with the Teslong mirror that was angled a little forward rather than at right angle.
I posted this solely to find out if anyone else had seen this. It's just a heads up to check your crown carefully before replacing a barrel that only needs to be re-crowned. Witt is a good reputable company. I'm not asking for a refund but I would have loved to have hear back from them.
I don't think all clamp-on Witts do this and that it might be just a unique combination of the crown design on my gun (recessed) and the Witt. It definitely creates a chamber just forward of the crown as the Witt is also recessed from the mounting surface.
I do know what gas cutting looks like. The cuts were spiraled at an angle matching the rifling. This was not crown damage due cleaning brushes. Again, I could only see the cutting with the Teslong mirror that was angled a little forward rather than at right angle.
I posted this solely to find out if anyone else had seen this. It's just a heads up to check your crown carefully before replacing a barrel that only needs to be re-crowned. Witt is a good reputable company. I'm not asking for a refund but I would have loved to have hear back from them.
I'm skeptical too. That's why I started this thread. If nobody else has experienced this, I'm happy. I just don't want to go through and continue on to proof because I would need to re-crown my bbl with the factory recess crown, reattach the muzzle brake and shoot another 500 rounds. I'm just not willing to do that.
My guess is the clamping reduced the bore diameter and created a tight spot at the crown, or just messed with harmonics.
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