Muzzle Brake install

[D.Camilleri]

My Bartlein barrelled 338 rum had a muscle brake and I just got a Terminator T3 to replace it. It needs a little bit shaved off so it will be timed correctly, can I carefully Chuck the brake in the lathe and trim it to time it or do I have to remove material from the barrel?

 

[Buttermilk]

I took material off the brake when I did mine.

 

[J E Custom]

My Bartlein barrelled 338 rum had a muscle brake and I just got a Terminator T3 to replace it. It needs a little bit shaved off so it will be timed correctly, can I carefully Chuck the brake in the lathe and trim it to time it or do I have to remove material from the barrel?

You can take a little off the brake to time it. Just stop short and torque it to find out where it will end up. (Use the same torque after it is trimmed)Then you can calculate the degrees you have to go using the thread pitch.

J E CUSTOM

 

[D.Camilleri]

My thread pitch is 9/16x24, the brake needs to move approximately 90 degrees, which should be around .010, am I on the right track?

 

[D.Camilleri]

My thread pitch is 9/16x24, the brake needs to move approximately 90 degrees, which should be around .010, am I on the right track?

I also have to bore the brake to .368, as it is .338 now for 30 cal

 

[Roeder]

I also have to bore the brake to .368, as it is .338 now for 30 cal

You can do this while you have it chucked up, and most likely do a serviceable job, but it would be best to set up the barrel and trim the shoulder on the barrel to time the brake, then bore the brake in place on the barrel. This will give you concentricity so that you don't need to have any more clearance than necessary. I don't know how much affect on accuracy a slightly out of concentricity brake might make. Some believe it is very important. Boring it a bit larger can give you a safety margin but brake efficiency is reduced with more clearance. If you have a nice, blueprinted, custom rifle and access to a lathe, why not go for the best possible job?

 

[J E Custom]

My thread pitch is 9/16x24, the brake needs to move approximately 90 degrees, which should be around .010, am I on the right track?

Yes. The actual ammount of gain by moving the brake 90o would be
.0104. But stop and test with less removal. Tightening several times will seat the threads and close the gap sooner.

Measure twice and cut once

J E CUSTOM

 

[D.Camilleri]

Well, I succeeded on the muzzle brake install. I started by removing .010 from the end of the brake after dialing in the 4 jaw chuck. Then I bored the brake to .368. It took several more attempts to get the timing just right and several more attempts to get the taper close. Since my barrel is Cerra Coated, I left the brake just a hair larger than the OD of the barrel. You can barely feel the size difference, but can't hang a nail on it. All in all, a success. Now to wait for the stitches in my left shoulder to come out so I can test fire!

 

[J E Custom]

Well, I succeeded on the muzzle brake install. I started by removing .010 from the end of the brake after dialing in the 4 jaw chuck. Then I bored the brake to .368. It took several more attempts to get the timing just right and several more attempts to get the taper close. Since my barrel is Cerra Coated, I left the brake just a hair larger than the OD of the barrel. You can barely feel the size difference, but can't hang a nail on it. All in all, a success. Now to wait for the stitches in my left shoulder to come out so I can test fire!

Glad it worked out for you. Heal up and get back to shooting.

J E CUSTOM

 

[D.Camilleri]

Maybe by this weekend I can see how well the Teminator T3 tames the 338 rum with lots of powder!

 

[tobnpr]

I would have reamed, and not bored.
Unless you indicated the brake bore (like you would dial in a barrel), you bored based on the OD of the brake- which may not be concentric to the bore.

No different than a barrel, as I see it.

Correctly sized reamer in a floating holder would simply follow the original hole, enlarging it while maintaining concentricity.

Probably not enough error introduced to cause an issue, but in "theory"...

 

[D.Camilleri]

Reamers are on my list of tooling, but I don't have any now. Once I was finished boring the brake I did set up my indicator and check the run out and it was within .001. The boring process did leave a small burr where the hole goes through the baffles, should this be removed?

 

[IdahoCTD]

I would have reamed, and not bored.
Unless you indicated the brake bore (like you would dial in a barrel), you bored based on the OD of the brake- which may not be concentric to the bore.

No different than a barrel, as I see it.

Correctly sized reamer in a floating holder would simply follow the original hole, enlarging it while maintaining concentricity.

Probably not enough error introduced to cause an issue, but in "theory"...

Reamers don't always follow the original holes, even with a float reamer holder. There is a reason chamber reamers have pilots. Boring it is better IMO but he should of bored it on fresh cut threads, weather it was on the barrel or a piece of steel. Not all brakes come with the center hole concentric to the OD. Drilling something that deep, even with the best turning center, almost never results in a perfectly straight hole. So if measures aren't taken to make the exit hole concentric with the OD when it's crowned it can be off several thousandths. Reamers are nice if you bore the hole concentric to the threads first.

I will also add that timed brakes tend to move or over rotate as you take them on and off for the first little bit. Machining ridges lap themselves smooth and then they tend to stop rotating. I always leave a timed brake just under timed when I install them because of this.

 

[Timber338]

I'm interest in how you like the T3 on your rifle once you get a chance to shoot it. I also switched over to the T3 on my 338 rum and am very happy. My old brake worked good too, but was very heavy. The T3 saved me a good bit of weight on the end of my barrel.