Not factory... they were produced by BarSto. I do know that a member of 10mmTalk has a 9x25mm Dillon barrel, which I believe was also made by them.

Most of the past attempts to get a .40 or .357 SIG barrel made has been through them, but they want a minimum of fifty barrels to be purchased (not for all types, like a total of both .40 and .357, but fifty of each type). When you try to get that together on the internet, it is impossible to get fifty people. You may get some that say yes, but not respond when you are ready... which would screw your run if you were just around fifty.