I own the SX 4 and shoot it quite well after some work on the synthetic stock. It shot low and left from the factory and its a breeze to alter impact with most semi autos. The gas system is identical to the Browning Gold and Silver as they share the same parent company. It is a simple effective gas system that runs fine with most loads. I shoot mostly 7/8 oz. loads in mine at clays and doves with no jamming.
The SX4 has the backbored barrel with an ID of .742 and a longer forcing cone with decent tubes from the factory though I shoot Trulock tubes which have .005 increments in constriction.
When cleaning be sure to lube the gas piston after using a very aggressive degreaser, it needs a little lube to move freely.
