Shotgunjones, thanks for the info. I fairly recently bought an SX4 for vermin at work and it only came with three choke tubes. I already had some Browning Invector Plus choke tubes that I bought in a box of bits at an auction. The SX4 lacks a full choke tube in the package so now I can tighten up when needed. It looked to fit and I couldn't see any join so suspected that would be the case. Thanks again and apologies to Wootang for coming in on his similar topic. Lagopus…..