GTA
Airguns by Make and Model => AirForce Airguns => Topic started by: rifle50 on February 09, 2018, 07:45:45 PM
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Hi All,
I had been asked by a contributor a question about my brake on Texan. It actually is another chance to impart some information about how well my Texan shoots. Another part of MY SYSTEM that didn't happen by chance..Will give info on what it took .......
For the less informed on Brakes, they are used to do just that, brake the recoil pulse, or LESSEN IT.
Getting the Texan upon firing with a stronger spring and 3500 psi, and 383 gr slugs during the recoil pulse, a target FRAME I use is 24" wide, and recoil would have scope jump completely off that frame and I have 1" pasters as targets all over it....Have to basically move bipod a lot to even find frame again. The point of all this is that the TEXAN just didn't happen to work well. Every part is thought out and assembled and no one mod made it great?
Not knowing the volume of gas expelled upon firing, and that increased as I shot heavier slugs at higher pressures, I ordered 3 different brakes and with ascending sizes. Will list at bottom with pics. YES, ALL 3 brakes have ports on top to help push muzzle down.
Following is what it takes just to fit them. I had slugged the barrel and knew the exact size of slug exiting to 4 decimals. My gunsmith did the boring of each......They were all 3 bored the minimum of .040" larger than slug passing through. Don't want slug to touch sides and don't want it TO LARGE of bore hole to waste gases going around slug as these gasses are directed into port baffles to help slow recoil. The manufacturer of last 2 brakes (pics) build custom tactical and long range rifles and they specify this. "Best efficiency is achieved by allowing the muzzle to be recessed back into threaded barrel nut of compensator by 1/4". This has the effect of forming a "cup," which directs the expanding gas forward into the baffles." From Powder Rifles. The Texan barrel was threaded 5/8" by 24 tpe to match compensators. Don't want muzzle end extending into the baffle port opening, or 1/4" short.
Ok, 3 brakes all bored and fitted to Texan....How do i test which is best.. When I shot 50 BMG competitively a manufacturer of BIG Clamshell Brakes, hung a gun in a pendulum device and measured recoil .......I did it a tad different but told me which was best... My bipod and rear rest achieve a gun on rails effect and with teflon tape on sliding surfaces moving with hands back and forth like it is mounted on ball bearings.
When I did these tests back in Dec of 2016 I had a partially modified valve. 382 gr at 855 fps giving 620 fpe....Eventually with fully modified and 430 gr achieved 908 fpe at max psi. The more gas pushed the better efficiency achieved in brake.
I have the solid rest......I just used a SHARPIE and marked a line on tank and on rear bag....ALL BRAKES made for Powder guns........
Fired with NO BRAKE.....Recoil slammed all way back and stopped with AR GRIP... So don't know how far it WOULD RECOIL but hit with authority. I stand away from gun, lightly touch trigger with index finger and thumb on guard and squeeze slowly and let recoil fully.The recoil length was ONLY 6" but hit very hard.
Brake #1 was for a large caliber pistol and smallest gas port volume. It would slide back 6" but came to all it would go 6"
Brake #2 was for a smaller caliber rifle......It recoiled rearward average 5 1/2"
Brake #3 was for a large caliber rifle. With the large ports i didn't think enough gas would be as effective as the previous smaller ports? It was the best, as recoil was down to 4 1/2" rearward travel.
If i had set up a little different and measured the FULL RECOIL with no brake, could calculate the efficiency of #3. But since it was the best of the 3, I didn't care, it worked.
I can now shooting off bench and at 3500 psi with heavy bullets and fully modified valve achieve 700+ fpe and looking thru scope at 30 power at 100 yds on a 1" paster, the scope crosshairs pretty much stay on that spot during recoil. Or it is real close, but I do back tank up with just a little shoulder behind, not a lot of pressure. I had some AirForce Frame weights since .257 days and threw them on too. Where it would completely jump up the muzzle and move all over , it is now tamed.
For those that don't watch my threads, I will attach a video put up shooting and watch muzzle at 800+ fpe....Tamed VIDEO https://www.youtube.com/watch?v=444ZPBPUmnU&t=3s (https://www.youtube.com/watch?v=444ZPBPUmnU&t=3s)
Pics are of the 3 brakes.......in ascending size of gas passing size#1, then #2, then #3 and is the one on the Texan...
Comments? ...........................Carl
Clicking pics get bigger
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Thank you for the detailed information on this aspect of your long range shooting. I LOVE you videos and applaud your amazing shooting achievements!
I am curious and have questions because I am working up a muzzle brake for my Texan.
You say that you used 5/8x24? I had looked at that thread size and thought the barrel wall thickness under the minor diameter of the threads would be too thin and if bumped or banged the barrel might bend or shear at the thread relief.
.625 major dia. with thread root minor dia. of .5781 to .5656 so figuring the worst case lowest min thread root of .5656 - .457 = 0.1086 / 2 = .0543 barrel thickness between thread root n bore.
I'm asking why you did not choose to go with the next standard brake size up which is M18x1.0 which has a min dia of .654 so .654 -.457 = .197 / 2 = .0985 barrel thickness under the thread, which is what mine is going to be machined to (when he finally gets around to it... a case of gunsmith disease, they promise what they can't deliver)?
And very interesting that the two large chamber design was more efficient than the four chambered one.
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Thank you for the detailed information on this aspect of your long range shooting. I LOVE you videos and applaud your amazing shooting achievements!
I am curious and have questions because I am working up a muzzle brake for my Texan.
You say that you used 5/8x24? I had looked at that thread size and thought the barrel wall thickness under the minor diameter of the threads would be too thin and if bumped or banged the barrel might bend or shear at the thread relief.
.625 major dia. with thread root minor dia. of .5781 to .5656 so figuring the worst case lowest min thread root of .5656 - .457 = 0.1086 / 2 = .0543 barrel thickness between thread root n bore.
I'm asking why you did not choose to go with the next standard brake size up which is M18x1.0 which has a min dia of .654 so .654 -.457 = .197 / 2 = .0985 barrel thickness under the thread, which is what mine is going to be machined to (when he finally gets around to it... a case of gunsmith disease, they promise what they can't deliver)?
And very interesting that the two large chamber design was more efficient than the four chambered one.
Thanks for Kudo's.....
The #2 and #3 brakes CAME with .625" x 24 tpi, and the .45 Pistol #1 brake came .578" x 28 tpi, and was bored and tapped to .625" x 24 tpi. Since my barrel is 1.100 " and ONLY threaded portion was the cut down to go into the thread 1/4" short of ports, and it is Tightened to the barrel shoulder with a wrench, no problem of blowing it off/breaking etc. I can't speak to your stock bbl thin dimensions?
I was surprised too the largest of ports was the most efficient..........In the 900 fpe video , at the extreme pressures the muzzle does rise just a little bit but is fine as don't shoot that way. That was just to see what valve could do........700+ fpe is accurate, powerful and extreme long range..............Thanks..............
Carl
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Jeez Carl, the brake you finally settled on looks like a big old 4 door sedan, with the doors ripped off!
So I guess it dumps all the gases out the side ports so that almost nothing is following the bullet out of the far end. Doesn't look like much would go out the holes in the top, but I guess it is properly balanced to also control any muzzle rise. To be honest, I don't have a single gun that I would be willing to just put a finger on the trigger and fire it. You really have tamed the recoil. Seems like a big part of your "system" is that the gun WANTS to stay on target. It also seems like more effort has gone into getting the gun to stay on target than has been necessary to get sufficient power out of the gun. Would you tend to agree?
Thanks again very much for all the solid information.
Lloyd
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Jeez Carl, the brake you finally settled on looks like a big old 4 door sedan, with the doors ripped off!
So I guess it dumps all the gases out the side ports so that almost nothing is following the bullet out of the far end. Doesn't look like much would go out the holes in the top, but I guess it is properly balanced to also control any muzzle rise. To be honest, I don't have a single gun that I would be willing to just put a finger on the trigger and fire it. You really have tamed the recoil. Seems like a big part of your "system" is that the gun WANTS to stay on target. It also seems like more effort has gone into getting the gun to stay on target than has been necessary to get sufficient power out of the gun. Would you tend to agree?
Thanks again very much for all the solid information.
Lloyd
I really don't know how much gas goes vertical? A lot of gas comes out and want the baffle plates to arrest the rearward momentum and it helps a LOT and the LARGE PORTS were best.
Actually worked on both power and control during building and testing. With Doug doing several modifications on the valve over time. I was applying ideas to help ACCURATELY and CONSISTENTLY shoot it ...........For best and consistent accuracy, you want to if possible, have gun TRACK straight back......This is for bench shooting. If hunting and carrying rifle, then this isn't necessary.
Thanks for the questions................Carl