I got the one with a 1/2-20 unf thread,
removed the thread protector on the barrel and it fit right on,
That centre cone you can move in and out for it's adjustment...
All I know so far is;
-I've seen similar ones on the 10m air rifles,
-when I posted about buying it on another forum a knowledgeable member told me that when they used one they found that they adjusted it to a certain point and it improved the groups but when they continued adjusting it the groups got worse so put it back to the optimal setting.
- in theory they work by diverting the unstable air when the projectile leaves the barrel away from the barrel.
-in my impact m4 only been able to experiment with it at 10m, and I'm still new with it...
It definitely has an effect. Much more positive when I am at a point in the tune where I have not tuned the efficiency part (just at reg and hammer) and not done the front Valve fine tune to reduce wasted air.
When I get the rifle to that "sweet" spot in the tune and I have a 1 hole group at 10 meters, putting it back on does not make the hole any smaller (obviously) but if I adjust the cone in and out, I can make it a bigger shot group.
Nothing conclusive, eager to see what these do upto 100.
Once I can get some range or field time I will post a thread on it so I don't hijack this one.
http://i.ibb.co/NgqxYKND/Air-stripper.jpg