I have the SA 459 with the win, inv, Mossberg thread pattern. I have a Down-N-Dirty Haymaker( was made by Indian Creek) .560 and an IC BDS in .555. Both have hot cores and are very tight at 40 with the Federal TSS 9's. I also tried a Carlson Long Beard choke(.568 I believe) with the pattern opening up to a more forgiving spread marginally. I hunted with the IC.