It is my understanding that the threads for WinChoke and Standard (short) Invector are the same. The early WinChokes had a knurled extension and a couple of dimples in the outer circumference to engage the wrench, rather than the slots on Invectors. I have a very nice Smith & Wesson (Howa?) 20 ga pump that came with WinChokes but I don't think I ever bothered to install Invectors in it. Briley could confirm interchangeability.