Gunsmithing Muzzle brake on small dia barrel

[ugsly]

I have a friend that wants to put a brake on his 7 mag. barrel is .506 at end muzzle and wants to put a 1/2-28 tpi brake on. Im pretty iffy about it being to thin but thought I'd ask and see what you guys thought.

Thanks guys,
Casey

 

[wareagle700]

Would it be possible to port the barrel or machine an integral muzzle brake?

 

[el gordo2]

I am far from a expert but here are my thoughts without a lot of thinking this morning...........

It's best to have a shoulder for the brake to mate with which actually aligns it. Since the barrel is .506" that would rule out 1/2x28tpi. The next somewhat standard size would be 7/16x28tpi. Major thread diameter being .437". That would leave appx. .034" to the side for the shoulder. That's as far as I am going since the type/style of brake wasn't mentioned.

 

[mallrat]

Ought to work if the barrel is concentric around the bore, or close enough to true it up. Thread enough for a jam nut since there won't be much of a shoulder. And make sure he understands that it may not be pretty. Get it in writing.

 

[Unknown]

I think this is a job for Mag-na-port.

 

[lancetkenyon]

My .270 Win has a muzzle diameter of .565 with a KDF brake. About .060 larger outside dimension, with a bore of .007 smaller (.277 vs. .284). With the difference of .506 - .284 = .222 ÷ 2 (two sides of barrel) = .111" of barrel to mill & thread. That is going to be really thin. I would look at either Magnaport as others have suggested, or a brake to fit over end of barrel and clamp on. I would then bet he will have to do some more load development, as the barrel harmonics are probably going to change.

 

[Straight Shooter]

A lot of the .750" diameter brakes only come with 1/2-28 and we put those on 30 cal weekly. 7mm no sweat. The .506 for a shoulder is the biggest concern here. The tapered end of that brake will be pretty sharp meaning it won't stand much torque tightening it up. A dab of Blue will hold it secure.

 

[GH41]

A 7 mag with a 1/2 profile at the muzzle??? I'd like to see a slow mo of the whip that thing has! I'll bet it flops around like a cooked noodle. Mag-na-port isn't going to tame it. I'd tell the guy no.

 

[Skunce]

Harrell's sells a 7/16-32, 5/8 OD radial port brake that I've used on small diameter barrels.

 

[el gordo2]

There is no doubt that it can be done. Lex Webernick of RiflesInc builds some very lightweight rifles up to and including .375 cal. with pencil thin barrels that have MB's installed. There is more than one way to skin a cat.

Sounds as if the Harrells is a good option being it's readily available.

 

[DALE '45]

Talk to the guy at Harrells, followed his advice on a light 300 Winchester. Worked out very well with no problems. Dale

 

[300sniper]

Who says the mating shoulders need to be at the rear of the brake and not the muzzle face?

 

[AKA-Spook]

Who says the mating shoulders need to be at the rear of the brake and not the muzzle face?

This

1/2 x 28 will be fine.

 

[McLarenross]

Who says the mating shoulders need to be at the rear of the brake and not the muzzle face?

Another +1 for this option. For a barrel that thin Id index the brake on the muzzle not a shoulder. 0.035" of shoulder is not adequate in my eyes plus that makes the steel around the muzzle only .076" thick with a 7/16" OD thread. Thread it 1/2x28 and index the brake against the muzzle.

 

[biffj]

I don't make a lot of brakes but I do a goodly number of suppressors. 1/2-28 should be just fine for the 7mm as there is plenty of meat left to handle the loading from the gas. As the others noted here at the end you don't need a shoulder at the rear as you can square up a bit of the muzzle face and use it for seating the brake. Even that isn't all that necessary as the brake isn't going to need as tight of a seat as a suppressor would. Unless you're making a 10 inch long brake there is little chance you'll hit it with a bullet. As long as your design is decent you shouldn't have any issues with gas upsetting the bullet and screwing with accuracy. On a suppressor you need to insure concentricity out to the end of the can and with a brake this is much simpler as its normally much much shorter. I like to have a good shoulder but its not absolutely necessary and red loctite will hold the thing on just fine.

Frank

 

[wittyhunter]

I would think you have enough room with the 1/2-28 threads. Most muzzle brakes will leave a little room for the bullet to travel freely. The muzzle brakes that leave too much room will allow the gases to follow the bullet out the muzzle and that basically defeats the purpose of a muzzle brake. I think the 1/2-28 is fine if you get a well made brake.

 

[MikeeBooshay]

There is no doubt that it can be done. Lex Webernick of RiflesInc builds some very lightweight rifles up to and including .375 cal. with pencil thin barrels that have MB's installed. There is more than one way to skin a cat.

I have several of Lex's rifles, they all shoot good, most are equipped with brakes, his brake is a design he came up with after much testing. I'll say this, they work. Other than being loud, I have a 300 WM, with a "pencil thin" floppy barrel, that is a hammer, you just aren't going to send a string of 10-20 rounds down range, it's not made for that. The recoil is not bad at all, even the "lighter than air" nephews have shot it well.

I'll put a caliper on one tonight when I get home, get you a good dimension.

 

[ugsly]

Thanks guys

Casey

 

[kortik]

Who says the mating shoulders need to be at the rear of the brake and not the muzzle face?

Exactly.