Why ream muzzlebrakes.

O

ossi

Guest
Hi.
I have reamer´s for muzzlebrakes in 6mm ,22 etc.
How do I use them when fitting a brake, and why?
Thanks in advance.
 
ossi

Before reaming the exit hole to final diameter it would be a good idea to take a light boring cut to make sure the hole is in perfect alignment with the bore. If it's crooked to start with, the reamer will simply make a bigger crooked hole.

We assume you have a lathe.

Ray
 
Installing brakes -- I thread the barrel to match the bore, install the brake and bore it to insure concentricity and ream to be about .020 over bullet diameter. I use reamers because I have at least 150 chucking reamers, frac, number, alph, and many more.
THEN, I indicate the o.d. of the barrel and finish the brake for a nice looking job.
 
Yes I have a lathe and I have installed brakes on rimfires. But I was wondering how to use those special muzzle brake reamers wich I bought from Brownells two years ago. (Don´t know why:confused:)

I mean, do you install the brake and then ream it while on the barrel in the lathe?
If memory serves, there was a guide on the reamer.?
 
Ossi,

The purpose of the Brownells reamers are to help finish the hole to what is thought to be optimal size over bore diameter - aproximately .012 inch over nominal bullet diameter.

Also, some riflesmiths order muzzle brakes with a small bore diameter and then bore and ream it to the size needed. The idea being one can always open up a 22 bore to 308, but it is harder to put metal back :eek:

I don't remember if the Brownells reamers had guides or not.

Good luck,
 
Where are you guys getting those numbers for the I.D. of the brake?? .012 over? .020 over??

All the ones I have done were .006 over. The tighter they are, the better they work- this is just physics.

Dennis
 
dennisinaz said:
Where are you guys getting those numbers for the I.D. of the brake?? .012 over? .020 over??

All the ones I have done were .006 over. The tighter they are, the better they work- this is just physics.

Dennis
Click to expand...

I think that there was an article in PS or maybe on the 'net from some fellow that did a lot of research on brakes. IIRC, .020 was slightly better than tighter or looser. If you consider that the gas speed is something like 5k or 6k feet per second and zooming past the bullet, you may believe that it affects the bullet. But it evidently does not from what I have read. Sure makes 'em seem louder, though.
 
Dennis,

You need to read my posting carefully.

He did ask about Brownells reamers.

It stated:

[The purpose of the Brownells reamers are to help finish the hole to what is thought to be optimal size over bore diameter - aproximately .012 inch over nominal bullet diameter.]

I was clearly stating what Brownells designed their reamers to do. It is on their web page and the instructions that came with the reamers.

Sorry if you read more into what I stated. Did not intend to confuse folks.
 
dennisinaz said:
Where are you guys getting those numbers for the I.D. of the brake?? .012 over? .020 over??

All the ones I have done were .006 over. The tighter they are, the better they work- this is just physics.

Dennis
Click to expand...

Dennis

In my case, the numbers come from the brake designers and manufacturers, guys like George Vais and Ron Bartlett.

Where did you learn that .006" was best? Sure, it would probably make the brake more effective but wouldn't it be better to allow more clearance and go to a better designed brake instead.?

JMHO

Ray
 
This is getting interresting.
But how do you use the reamer?
Do you ream while the brake is on the barrel?
 
dennisinaz said:
Where are you guys getting those numbers for the I.D. of the brake?? .012 over? .020 over??

All the ones I have done were .006 over. The tighter they are, the better they work- this is just physics.

Dennis
Click to expand...

Dennis

I certainly think that you have not looked deeply enough into how brakes work and how the bullets fly once they leave the muzzle. Too tight a clearance will allow for bullet contact with the inside of the brake. The bullet leaves the muzzle on the helix angle of the rifling. As you use longer and longer bullets with faster twist rates-the slight angle of departure can lead to problems with accuracy if the bullet touches the inside of the brake.

The comments about gas blow by are also appropriate.

Jim
 
Dennis,
I asked you where you got the info about Tony getting better barrels than you and now I will ask where you got the .006 info.
Butch
 
Butch, you have me mixed up with someone else!!! I don't even buy BR barrels.

I don't believe I have ever made a comment about Tony Boyer. If I have, please direct me there and I would be glad to comment. I always thought that Tony used Shilen barrels. I have made a comment about the ONE Shilen barrel that I had which I stated was their el cheapo "Lone Star." Other than that, I can't imagine what you are getting at.

As for the muzzle brakes- my comment about where you guys get the ID sizes was based on the fact that two posters gave two different oversizes. I was just wondering if there was some magic "Hatcher's Notebook" out there that specified that .020 is better than .012 or whatever number you want to use.

I designed some muzzle brakes bases on what Dana Campbell from Mountain Rifles (Gunworks?) used to put on his rifles (before he was killed in a car wreck) and what McDonnel Douglas/Boeing uses on the Apache helicopter gunship. At the time I lived right close to the Apache factory and knew several engineers that worked there. After careful scaling and consulting with with these guys as well as two guys at an Aerospace shop in Mesa, I came up with design and .006 as the MINIMUM safe oversize. I had some friends in this Aerospace shop who could make personal stuff during their down time. As these brakes had to be timed, they were out of my league in terms of machining skill required. They made them for me and used a chucking reamer to make the final cut. Most of the Boeing/Apache stuff is classified or proprietary, but verbal details were easy enough to get. They tested hundreds of brakes!!!

ALL of these brakes went on 300 WBYS and .006 oversize did indeed provide the most reduction in recoil of any we tested. Most of the brakes were originally made with 440 C stainless but it didn't take metal finishes well and we switched to 416 obtained from barrel drops from Derrek Martin.

If the rifles didn't shoot 150 grain bullets into .5 MOA, they were rebarreled. Careful inspection of the brakes showed no evidence of bullet contact. Maybe we just got lucky or maybe the Army knows what they are talking about. The muzzle brake thing was a fad for me and after I nearly deafened a guy during a deer hunt in Mexico, I no longer use them-at least on hunting rifles. I could be talked into using them on prairie dogs or 1000 Yd BR.

Sorry for all the confusion. I will try and find a photo of one of the brakes.

Dennis
 
ossi said:
This is getting interresting.
But how do you use the reamer?
Do you ream while the brake is on the barrel?
Click to expand...

You use the reamer like a chamber reamer slow rpm and feed.
You dont want to ream the brake when it is on the barrel, you ream it in the chuck!
 
Dennis:
I hope the link below is of some help. I personaly just finished installing a Harrells brake on my .338 yesterday and used this link as a guide line....As far as when to ream/ bore/ drill/ cut etc., I will not elaborate just use good machining practices and think it out....I will mention that a good frend has had 2 brakes installed, one from MagnaPort and a Vias and both were .338's...One was .020 over and the other was .021 over bullet dia....Good luck...Rick

http://www.rvbprecision.com/articles/10/adventures-with-muzzle-brakes
 
I have always used .020" over bullet diameter. Many times I have seen the hot gases and pressure actually push metal into the I.D. of the brake forming somewhat of a burr which reduces the clearance. I wonder if the .020" was reduced if that would reduce the effect I have witnessed.
 
Rick, that was an interesting read. I agree with most everything he said but I didn't do nearly as much testing as he did!!! I am going to have to measure one of the brakes as now I am not sure if I had .006 TOTAL oversize or .006 all the way around (.012 total).

I did find and so did Dana that with a 300 WBY and even more with a 30-378, I could use three 1/2" holes rather than just two. I prefer the two hold design as it doesn't require a dividing head and it works better when shooting prone as the dust that is kicked up is far enough away that it doesn't get you.

The most effective brake i have ever seen was made by a guy in Tempe AZ- I think his name was Charley Newman but I could be wrong- it's been a few years. He made his brakes in two pieces and actually bored the vent holes on an angle facing back to the shooter. A friend of mine had a bad ATC accident in Mexico and broke his back. He couldn't shoot his rifle (7mm Rem mag) for the pain. I heard about this Newman guy's brakes.

We went and had one put on and I was amazed at how good it was. The downside was that it was horribly loud!!!

The worst brake I ever saw/used was the Browning BOSS!
 
If you have an undercut at the bottom of the thread you probably have room to ream the brake when on the barrel. I do it that way, no problems.
 
dennis sir

i have seen the same effect as joel stated in his post .if you shoot that rifle much you might want to remeasure brake on the inside . with those tolerances you listed if your brake has a chamber cut inside the brake what will happen any where 100-800 rds your hole will close up to be about .001 on each side.i would say with the carbon build up on top of that it could get bad. the metal will get pressure peened and make the hole close up on the inside edge of the exit hole,that is the only time the piloted reamer will get used in my case,it will recut the hole to dia all the way through.now if your internal design has no chamber but has the hole all the way through the brake at .006 over bullet dia then the trailing edge of the side exit holes and the flare area at the crown get peened inwards and close up the dia and both ways your brake will close up,your at least safe with .010 on each side if any peening has taken place.i have a 308 baer that kicks like a 243 with a hole at .012 on each side and i reem it every 200 rds. if you lose braking by opening up the hole you just have to make it up somewhere else within the brake.hope this helps sir . tim in tx
 
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