muzzle brake thread dia...?

M

mike in co

Guest
300 win mag, truck axle bbl.....0.9 at muzzle( 30 in long installed).
1000 yd br light gun..weight is not an issue i am under 17 with the brake before turning down for threads.

the threads on the brake are 5/8"

i was thinking of boring out and doing 3/4"

any reason to leave it at 5/8"s ???

any reason to go out to 3/4"???

will turning the muzzle end down to either od cause an internal dia issue ?

just do one and move on ??

thanks
mike in co
 
Last edited by a moderator:
Mike

I don't think the thread diameter or TPI will make any difference. It's the relationship between the muzzle face and the ports, and the "straightness" of the exit hole that matter. I have made my own brakes and some have some weird threads, like .527 x 28 TPI. Why? Because that's the way they came out. I wish I could be around in 50 years when someone sees some of my brakes and wonders where the hell those dimensions came from. ;)

Ray
 
In theory you want the threads as large as possible over the bore diameter... but I think 5/8" with a finer rather than coarser thread will work okay.

Lots of theory on turning and threading a muzzle...

This should bring up lots of responses...
 
I bore them out to a custom thread that's just under barrel diameter. To all who think it doesn't matter please tell us you've slugged a bore or two.

:)

al
 
Mike, since it is a custom installation, there is no reason preventing you from boring and threading the Brake for the largest size that your barrel will accomadate, or the OD of the Brake will handle. You probably know this, but just be sure you get the center hole dead true when you chuck it up.

If it is a cut rifled barrel, the general consesus is it does not make much difference if you turn the barrel to a smaller diameter, but buttonned barrels, (which are lapped after the contour), are rumored to change ever so slightly if you turn it any appreciable amount. I would consider .900 to .625 an appreciable amount. Internal stresses that are a product of the button proccess are supposed to be the culprit.

Why even go to 3/4. Chuck the barrel up, see what the largest straight diameter that can be established on the end, and make it that, if the OD of the Brake isn't too thin........jackie
 
BROUGHTON BBL.....

this issue was the reason i asked.
and while i had planned on 3/4",,looks like turning to .800 and cutting 28tpi, and making the brake match.....

thanks guys
mike in co
 
Mike

Never underestimate the looks of the finished product. A good looking brake, the same diameter as the barrel, simply has to be more accurate. Those with a big knob on the end, look like somebody's dingus and may be OK on TV or in movies, but not on the line. :rolleyes:;);)

Ray
 
Last edited by a moderator:
its close to a match now...when it moves up the bbl for the thread length....well it will be real close....may have to do a litltle blending...
same finish....
 
The less material you remove from the muzzle of the barrel, the better. Therefore, I would use 3/4" diameter on a .90" "Truck Axle" barrel..........
 
... and I will still bet you can not see any difference in accuracy between the 5/8 inch thread and larger thread diameters if all else is equal... :D
 
Mike

One thing that hasn't been mentioned - some of the more complex brakes are designed to work best with a certain tenon diameter and length. The maker will include a diagram of the tenon along with the brake. Before boring out the inside of the brake you should call the maker and ask if what you plan to do will affect the function of the brake. Better safe than sorry.

Ray
 
Dennis Sorensen said:
... and I will still bet you can not see any difference in accuracy between the 5/8 inch thread and larger thread diameters if all else is equal... :D
Click to expand...

I agree, I have done about 75 brakes over the last couple of years with varying thread/barrel diameters and could tell no difference in accuracy. Mind you we don't shoot Benchrest out here though. I have a 6.5-06 with a 1.210 diameter Shilen barrel that shot in the low .3's, and after cutting a .750 thread diameter 32 pitch and installing a Harrell's brake, it now shoots in the mid .2's. Probably a coincidence, but who knows.

Med.
 
Last edited:
A few years back I had Shilen HV barrel that would not make weight for LV on my daughters old sleeved XP. I put it between centers on my old south bend ,set the taper attachment,and took a lot of material off. That summer at an NBRSA match down in Kane,Pa. she shot a .186 agg. with that barrel. I have also turned down more than a few Douglas and Shilen tubes with no ill effect, so I seriously doubt the difference in diameter on the last half inch of a barrel would be a tie breaker.
 
I seriously LOVE the fact that most people can't see a difference :) it gives me a job. Shucks..... maybe there's a market for universally threaded tuners? Someone could make up tuners on a 5/8 thread and just screw 'em onto ANY competition rifle, mix and match from light Palma to heavy varmint....

And then there's the hunting or varmint rifles,

I simply can't understand those people who say "It's a HUNTING gun, what's the difference?? 1/4moa, 1/2moa or 1moa the animal won't know the difference!"

differ'nt strokes

al
 
A little more "food for thought" on muzzle brakes. If I remember correctly button barrels are stress relieved AFTER they are rifled, then contoured. During the profiling process the chips change color even while being flushed with a coolant. The finish roughed barrel looks like a fine thread. If the barrel is not lapped "Douglas" it is then air gauged and then if found with in tolerance stamped accordingly. The point I'm trying to make is this! Am I to believe that after that kind of abuse, putting a muzzle brake on will release internal stresses detrimental to accuracy? Like a tuner it will change point of imact but that is another story. I usually don't get this involved in these matters but its been a LONG winter.
 
You must log in or register to reply here.
Back
Top