Problem with big bores is they're difficult to regulate. It requires a HUGE plenum, and a HUGE valve to dump the air in the plenum without getting "valve dump". An expert in regulating big bores is Mr Doug Noble. He's fabricated his own regulators for his bench rest competition big bores. The guy is next level in his thinking and his product. But his regulators are an anomaly. The only "regulated" big bore is the hammer, but it's HUGELY wasteful on air. Just sighting the thing in will kill your fill tank. But if you bought the .50 Texan from AF, and you got yourself the African Air Ordinance upgrade kit, you can go from a 200 BAR fill on the bottle to a 300 BAR fill. This will get you at least 6 or 7 more shots (if not more) than the stock model, which will get you exponentially more shots than the Umarex Hammer will. There's the "bell curve" you experience from shooting a non regulated PCP. But you can predict the shot placement from one shot to the next when you sight in your rifle if it's an unregulated big bore. You just need to keep track of shot placement in a notebook when sighting it in, and you will see that by and large the shot placement will be pretty consistent with your notes..