Gunsmithing Really dumb Brake question

[renegadelizard]

Hey all,
First let me qualify what you are about to read..

First: I am by no means a gunsmith...i've done quite a bit of work on my own guns, mostly pistols and ar's, but that's about where it ends. I've been to a few armorer schools, but as most of you know, these arent really in depth..

Second: I dont intend to do this to my stick, im just contemplating how it would work.

Three: If i ever did attempt to do this to my gun, i would have my friend do it for me..he is an accomplished machinist.

So, here it goes...what would happen if you were to counterbore the barrel of say a 30 cal barrel, say to .500 and then drill holes say 11 degrees rearward from the bore axis, evenly spaced around the circumference of the muzzle? Is this essentially magna-porting? Would it be effective as a brake or would it just make more noise? What would it do to accuracy?

Please note that im asking this because i just read a thread from a guy on here that was going to try to thread his own barrel...clearly a dangerous undertaking for a shadetree smith, so i figured something like this might be a better option for guys out there who have that DIY itch.

Lastly, where would a person buy a barrel that is already threaded for a break for a reasonable price? I saw that a few have recently sold on the for sale forum, but they seem to be pretty scarce and go fast on here?

Thanks for reading and dont blast me too bad...im pretty thick skinned but i have wittle feelwings too...lol...

 

[Hateca]

Re: Really dumb Brake question

Yes it's possible and has been done before. Remington doses something along these lines with their funky factory rifle with a triangle barrel.

Will it act like a brake? Yes if the ports are done correctly.

Will it make more noise? Yes.

Will it screw accuracy? It can but if done correctly it shouldn't

Barrels already threaded for a brake is most likely someone’s used take off barrel that had been threaded when it was installed on their rifle.

Better option is just have your barrel threaded for a thread on brake and get a thread protector so you can have the best of both worlds. You also live in a free state so the best brake is a suppressor.

 

[colchester]

Re: Really dumb Brake question

I did something similar on a TC barrel in 444 marlin. Ill try to explain. Lets say the barrel od was .750 I bored in from the muzzle about 1.25" deep and .500 id leaving the .250" closest to the muzzle the proper dia. for a 1/2 x 28 tpi thread. I crowned the rifling inside the hole with a boring bar,similar to the way I would finish any barrel crown. Next I made a plug the same od as the barrel and threaded it to fit the thread in the barrel. Lastly I drilled a hole in the plug and bored it true for the bullet to pass through, .030" over bullet dia IIRC. Now you have a barrel with an expansion chamber installed take it to the mill and drill holes to create the brake. I hope this makes sense BTW it worked very well.

 

[renegadelizard]

Re: Really dumb Brake question

at what angle did you drill the holes in the brake?...I was taking a guess at 11 degrees, seeing as how it promises the best accuracy on a crown, but would that be sufficient to act as a brake, or would you have to go to say 30 degrees?

 

[renegadelizard]

Re: Really dumb Brake question

i have debated long and hard on putting a can on the end, but i just cant convince myself that its worth the money...there are still too many other guns out that im trying to buy up..lol..

 

[kingjoey]

Re: Really dumb Brake question

The biggest problem you're going to have is that your new muzzlecrown is most likely going to be 22.5 or 45 degree because most drill bits and reamers don't leave an 11 or 12 degree chamfer. Also, the crown won't be cut cleanly because it is being reamed/drilled rather than turned with a cutting bit. A good example of this is the milsurp M38 Mosin-Nagants out there, most had been "counterbored" by the arsenal when the guns were rebuilt. They basically take a drill bit around 3/8" diameter, set the barrel up in the lathe, and drill the worn/chewed rifling out of the last 1-2" of the barrel to restore passable accuracy. This poor muzzlecrown will also result in poor initial stabilization of the bullet (wobbles) and may result in the bullet hitting the inside of your brake.

If you were to do this 'brake' mod, you would need to ream the bore out to .030-.035 larger than the bullet diameter (it will help the brake's efficiency). As far as angling the ports, don't worry about it, between the relatively small diameter of the 'brake', and the slight angle (you mentioned 11 degrees), the brake will actually run worse because more propellant will flow back into the bore path and continue moving forward rather than going out the ports. Anything more than a 90 degree turn and your propellant isn't going to redirect as efficiently. A lot of angleport brakes will have a bit of expansion room to allow the propellant to move outward away from the bore so that it is less prone to flowing back into the bore. You aren't going to have enough room for that when making it out of the barrel.

Also, angleporting generally is inefficient, but the additional reduction made by reversing the propellant direction usually outweighs the lower efficiency. We build a few angleport brakes such as the KA-0430 and KA-0450, but they have a 'gas trap' in them to specifically prevent flowback and increase efficiency dramatically, but they are also 1" to 1.5" in width depending on the caliber. In all honesty, you'll probably have a hard time doing this job and getting the desired results. It would take a lot of specialty cutting tools to do it 'right' and even then it would take a bit of work.

Our KA-1830 brake is probably similar to what you're trying to achieve, but we do a special threading/profiling on the barrel end and then add that brake and profile it to match the barrel. Same general concept but it is being added to the barrel so we can do a true 11 degree (or even recessed target crown) on the muzzle then add the brake portion in a separate operation. Short of getting custom bits made to do the boring and crowning correctly, I think you're going to end up with less accuracy out of your gun when you're done

 

[renegadelizard]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body"> A lot of angleport brakes will have a bit of expansion room to allow the propellant to move outward away from the bore so that it is less prone to flowing back into the bore. You aren't going to have enough room for that when making it out of the barrel. </div></div>

Is this why brakes such as the Vias have holes bored perpendicular to the bore through the ported holes?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body">'gas trap' </div></div>

I really must let my ignorance shine here, but what exactly is a gas trap? If they had an idiot smiley, i would use it right about now...I really understand very little on this subject, thats why i appreciate all you guys out here who know what's what...

 

[chpprguy]

Re: Really dumb Brake question

I "thought" that as the inner diameter of the brake exceeded the bullet diameter by more than .020" you began to see a dramatic loss in brake efficiency?

 

[kingjoey]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body">I "thought" that as the inner diameter of the brake exceeded the bullet diameter by more than .020" you began to see a dramatic loss in brake efficiency? </div></div>

.020" is much smaller than most brakes run. When the bullet leaves the barrel, it 'wobbles' slightly until it achieves gyroscopic stability. Obviously the bore of the brake needs to be slightly larger than the bullet diameter to prevent the bullet from touching the inside of the brake while passing through. As a rule of thumb we go .020-.030" over on standard threaded brakes, and go down to .014" on some of our KA-1830 versions. Generally speaking, .030" is a pretty efficient yet safe clearance.

 

[kingjoey]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: renegadelizard</div><div class="ubbcode-body">
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body">'gas trap' </div></div>

I really must let my ignorance shine here, but what exactly is a gas trap? If they had an idiot smiley, i would use it right about now...I really understand very little on this subject, thats why i appreciate all you guys out here who know what's what...
</div></div>

Our angleport brakes incorporate a wedge in each port that mechanically does the first redirection of the propellant and prevents the propellant from flowing back into the bore when it does its second redirection. It basically increases the percentage of propellant that gets redirected by the brake and increases the efficiency that it is done with.

 

[renegadelizard]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: renegadelizard</div><div class="ubbcode-body">
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body">'gas trap' </div></div>

I really must let my ignorance shine here, but what exactly is a gas trap? If they had an idiot smiley, i would use it right about now...I really understand very little on this subject, thats why i appreciate all you guys out here who know what's what...
</div></div>

Our angleport brakes incorporate a wedge in each port that mechanically does the first redirection of the propellant and prevents the propellant from flowing back into the bore when it does its second redirection. It basically increases the percentage of propellant that gets redirected by the brake and increases the efficiency that it is done with. </div></div>

Okay...i think i understand that but i couldnt draw a picture of to save my life..you guys are way over my head..which is an admittedely easy place to be..lol..so basically, this is not something that the average guy could do, or for that matter even one with the rudimentary knowlegde of tools and machining...one must have a pretty in depth knowledge of ballistics and or physics as well as a ton of experience...thank for all of your responces guys, i have learned that there is quite a bit left to learn...on a side note...can anyone install one of your angleport brakes or is there a lot of tuning to be done on it?

 

[kingjoey]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: renegadelizard</div><div class="ubbcode-body">
Okay...i think i understand that but i couldnt draw a picture of to save my life..you guys are way over my head..which is an admittedely easy place to be..lol..so basically, this is not something that the average guy could do, or for that matter even one with the rudimentary knowlegde of tools and machining...one must have a pretty in depth knowledge of ballistics and or physics as well as a ton of experience...thank for all of your responces guys, i have learned that there is quite a bit left to learn...on a side note...can anyone install one of your angleport brakes or is there a lot of tuning to be done on it? </div></div>

You're going to have a hard time getting the results that you want unless you invest in a lot of specialized tooling. I could do what you're talking about with just a lathe and mill and some basic bits and make it look really good, but the accuracy and performance would be crap compared to leaving your factory crown intact and putting on a dedicated muzzlebrake. To answer your second question, our .30 and .33 cal brakes use crush washers to index, pretty simple install.

I would recommend having a smith thread your barrel and install a dedicated brake to it rather than trying to machine the barrel into a brake.

 

[chpprguy]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chpprguy</div><div class="ubbcode-body">I "thought" that as the inner diameter of the brake exceeded the bullet diameter by more than .020" you began to see a dramatic loss in brake efficiency? </div></div>

.020" is much smaller than most brakes run. When the bullet leaves the barrel, it 'wobbles' slightly until it achieves gyroscopic stability. Obviously the bore of the brake needs to be slightly larger than the bullet diameter to prevent the bullet from touching the inside of the brake while passing through. As a rule of thumb we go .020-.030" over on standard threaded brakes, and go down to .014" on some of our KA-1830 versions. Generally speaking, .030" is a pretty efficient yet safe clearance. </div></div>

Thank you for the explanation....

 

[renegadelizard]

Re: Really dumb Brake question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kingarmory</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: renegadelizard</div><div class="ubbcode-body">
Okay...i think i understand that but i couldnt draw a picture of to save my life..you guys are way over my head..which is an admittedely easy place to be..lol..so basically, this is not something that the average guy could do, or for that matter even one with the rudimentary knowlegde of tools and machining...one must have a pretty in depth knowledge of ballistics and or physics as well as a ton of experience...thank for all of your responces guys, i have learned that there is quite a bit left to learn...on a side note...can anyone install one of your angleport brakes or is there a lot of tuning to be done on it? </div></div>

You're going to have a hard time getting the results that you want unless you invest in a lot of specialized tooling. I could do what you're talking about with just a lathe and mill and some basic bits and make it look really good, but the accuracy and performance would be crap compared to leaving your factory crown intact and putting on a dedicated muzzlebrake. To answer your second question, our .30 and .33 cal brakes use crush washers to index, pretty simple install.

I would recommend having a smith thread your barrel and install a dedicated brake to it rather than trying to machine the barrel into a brake. </div></div>


A buddy of mine is a pretty accomplished machinist..im thinking of taking it to hime and lettng him cut about 6 inches off the barrel and thread it for me...he has access to some high dollar equipement and he knows his way around guns...thanks again for the help..