For IDPA what would be a good suggestion for my 3906, research does not provide a wide selection of choices. It seems that there are three choices Bianchi Black Widow or a ShadowII and two by Safariland or an Uncle Mikes (not crazy about that for competition)

I have a 3904 and use the Safariland holster that you can adjust to the pistol. I forget the exact model number, but it REALLY works great. I wholeheartedly recommend it. You will not be disappointed.

Any holster made for a 39-59 series gun will work for your gun. You need to decide on OWB or IWB. I use my Kramer #3 in IDPA with my M39-2.

There are plenty of holsters made by all makers and can be found easily in local gun shops, pawn shops, gun shows, eBay, etc.

Do a search on eBay using S&W 39 or 59 holster and you will have MANY to choose from.

I seldom pay more than $20.00 for a holster.

Randy

It will also depend on if yours is a round or square trigger guard. I find that most Sig 220/226 holsters will work with either.

How about a Don Hume J.I.T for IDPA?