TargetTalk

I am interested in learning and experimenting with compensators design, but I couldn't find a technical (meaning, with numbers and equations) article discussing how to design one from scratch. The ones I see advertised in various places look bogus and snake-oil.

Not sure if anybody here can answer a few questions:
1) for a .22, what should be the diameter of the exit hole? I assume anything touching the bullet after the crown would make precision worse.
2) What's the criteria to size and space the holes to reduce muzzle rise?

I plan to start experimenting with a Ruger precision rimfire, a blank such as this https://www.ebay.com/itm/Steel-Muzzle-B ... 2188427314, and a precision accelerometer to take the readings at the end of the barrel.

Any suggestion is appreciated, thanks

I can't help you much, but I can tell you that the famed "TurboComp" was designed and sold by World Champion and engineer Don Nygord.

> Nygord's Turbo-Comp fits 12mm/.471" airgun barrels. It is exit-bored 5mm for 4.5mm pellets.

Thanks Rover, that answers my first question :-)

My guess is that no information is widely available, and that existent designs are at least in part (if not mostly), based on gut feelings and a little testing. If there were a real science to it there would be a lot more similarity among designs. Should you want to be science-based you would need to look into fluid dynamics, and my guess is that there would be a difference between sub- and supersonic muzzle velocities. On the other hand, it seems like a fun project to get into; using an accelerometer is a nice idea.

It just popped into my head that the NRA did some research and developed the 11 degree dish crown for muzzles. It might be a place to start.

I would think that an exit hole large enough to allow the projectile to exit without touching, could be theoretically made smaller as recoil is reduced by the enlarging or addition of ports.
My Nelson conversion has a compensator on it that is bored for the 45acp. Does it work?? Not so sure it works as a comp but the muzzle weight is what I was really looking for..

I built a compensator for a 1022 clone about 25 years ago that still works pretty well. It was actually an AMT Small Game Hunter rifle that I bought back when the Chevy Truck Sportsman's Team Challenge first started. I worked for a big pharma company in the development area, and we had a well equipped machine shop, and the german guy that ran it kinda liked me, so he let me do some stuff myself in there for my lab projects. He was a shooter too, so that led to me drilling and tapping my 41 barrel for a dot sight, and making swinger targets from the scrap bins he had in there. I decided to try making a muzzle weight for my rifle, which turned into a compensator fairly early in the construction. I turned down and threaded the barrel, which wasn't hard since it had a parallel section near the muzzle. Then I took a 5" long piece of 1" stainless bar stock and drilled that out to ½" most of the way through it, and threaded that to match the muzzle threads. I had the same dilema you mention about how big must the exit hole be to insure that the bullet doesn't hit it going through. He started talking to me about line-boring to insure that everything was perfectly aligned but I wasn't fully sold on the redirection of gas part yet, and wanted to just make it as a weight, but it seemed like it might be too heavy. Then we started cutting slots in the top half to remove weight, and it morphed into a compensator. Eventually I settled on a ¼" exit hole, and figured that having the bullet pass through about ¾" of a ¼" hole would give enough time for the gasses to expand and move up and out the slots we cut to lighten the whole thing. I figured that if a .22RF is .223", then .250" would leave a space of .0135" around the bullet for clearance. Bullets don't touch, so I guess it could be tighter, but alignment would then be more critical.
Some things I learned in that process: The closer to projectile size you make the exit hole, the more gas (or air) is blocked and redirected up through whatever ports you have as vents. That hole is only blocked for however many milliseconds it takes for the cylindrical projectile to pass through it, so a longer (deeper?) hole at that smaller diameter gives more time for the propelling gas/air to be redirected. The longer your compensator is, the more critical alignment is, since that exit hole is farther away from the end of the rifling, and there is always movement involved when you're shooting. Projectile velocity also factors in here. I never put any kind of baffle plates inside my comp, and I notice that only the slots farthest from the barrel get dirty, so even though mine is long, the slots nearer the threads probably don't see much gas. Baffle plates would change that, but they need alignment too. Buddies have told me that it's really only the far end of the comp that has smoke puffing out of it when I shoot.
You could probably do a lot of advanced engineering calculations and look into fluid dynamics for making flow paths more efficient, or you could just go with whatever picture you have in your mind's eye and make modifications as you go along. I enjoyed doing this, and I think Werner, the machinist that helped me, enjoyed teaching me how to use a lathe and the mills, and letting me figure stuff out.
I say go for it!

gimgim wrote: ↑Tue Apr 09, 2019 12:08 pm I am interested in learning and experimenting with compensators design, but I couldn't find a technical (meaning, with numbers and equations) article discussing how to design one from scratch. The ones I see advertised in various places look bogus and snake-oil.

Not sure if anybody here can answer a few questions:
1) for a .22, what should be the diameter of the exit hole? I assume anything touching the bullet after the crown would make precision worse.
2) What's the criteria to size and space the holes to reduce muzzle rise?

I plan to start experimenting with a Ruger precision rimfire, a blank such as this https://www.ebay.com/itm/Steel-Muzzle-B ... 2188427314, and a precision accelerometer to take the readings at the end of the barrel.

Any suggestion is appreciated, thanks

Have you seen this site for formulae-based design?
https://www.sciencedirect.com/science/a ... 4718300758
Regards
John

Wow, no, this is fantastic! Thanks jliston48