I was also interested in this conversion for my own Browning HP in .40. I read somewhere that Bar-Sto barrels made a .357 SIG barrel for the HP. but when I checked, it wasn't listed on the Bar-Sto web site. So I e-mailed Bar-Sto, asking whether they made the barrels. I got a return e-mail from Irv Stone, telling me that Bar-Sto did indeed make the .357 SIG barrels for the HP for a brief while, but that they discontinued them because of problems making the .357 SIG work in the HP. Maybe others have had better luck, but I decided if Bar-Sto couldn't get it to work right, it probably wasn't worth pressing the issue. I got a Glock 31 instead. As always, YMMV.