I posted up an initial impression review back in February which I will leave a link to here. handguns is why manufacturers are able to produce conversion barrels that will allow your G21 or G22 to shoot 9mm instead of .45 ACP and .40 S&W, respectively. Compatible with ½-28 threaded barrels our compensator requires no modification to your 9mm Glock.. This RTB 9mm G19 Gen 3 Upper Slide is exactly what you need to complete your factory Glock lower or Poymer 80% compact frame. 00: 16h 7m: 14940609. Pick up a slide at a huge discount with free shipping! More ports and expansion chambers are even more effective at reducing recoil/muzzle rise, but they also reduce bullet velocity and slide speed more, respectively. It features a 2 chamber design (1 vertical port and 2 side venting ports. Advancements in several areas of gun design and practice have enabled carry pistols to allow the shooter to express their skills and the compensator is an additional item that can assist in that goal. All four points of the spider harness can pivot independently and are connected by our unique clover trademark.