This gun is chambered in .40 S&W. The gun is set up with a minimum spec chamber so that it can be fit to a specific magazine type. This allows the rear of the case to be fully supported beyond the normal full support barrels. The slide is 4oz heavier than a 22 slide. The recoil spring is a stiff 24lbs. What all of this means is the gun is intentionally set up to shoot +P all the time. The slide/ barrel lockup is hand fit and is much tighter than a Glock. Many factory loads will barely cycle this gun or not cycle it at all. This adds up to 700+ ftlbs of muzzle energy. This is a better all around set up than the 22/24 hybrid system. The gun is a tack driver. At 25 yards from a rest it will put all shots touching even with my bad eyes. It actually feels more like a 1911 than a Glock even though it is based on a Glock. I would say don't try this at home but anyone willing to put in the hours of hand fitting required to get the accuracy and performance from one of these is probably already aware of the time and money it takes to do it. I love it. Its not a 44 magnum flat top but it is fun and comfortable to shoot.