I have 3 of the center fire tuners. I have had great success with them on 6 different barrels.We use the Gene Beggs tuners, which Gene no longer makes but we do now. They add four ounces to the muzzle minus the weight of the thread you take off. They work for us on rimfire, air, and centerfire very well. The rimfire and air rifle tuners can be purchased in clamp configuration due to the small diameter of those barrels.
I have 2 tuners, on different rifles [1 on a 30 br the other a 6bra]. one the expansion chamber is in the rear. The other is in the front.
I don't know how else to describe it.
They both seem to work. My question is - is one design better than the other?
ty Don