Hello y'all and happy new year!I'm looking for a 4 inch 357 sig barrel for my m&p 40.S&W only has it in 4.25 or 5.I know someone here will have the answer.Thank you.
S&W discontinued .357Sig a few years ago. You can still find barrels for the fullsize and Compacts (1.0s) OEM and aftermarket.
A quick check of the usual aftermarket brands didn't show a 4" barrel. Your best bet would be to contact them directly to see if they have any plans for one.
Perhaps someone else will have better info for you.