No one is making conversion barrels for the M&P 2.0 Compact (4") Conversion barrels so I had mine custom made.
SOLD A S&W factory barrel in 357 Sig turned down by my gun smith to 4" and an 11 degree crown installed $175 Shipped.
AVAILABLE: A Storm Lake stainless steel 40 S&W to 9mm conversion barrel. Same thing; gunsmith turn it down and installed an 11 degree crown. $200 Shipped.
Both barrels are drop in and have been tested for reliability.
Sorry, no Pay Pal, prefer a postal MO for immediate shipping or a personal check that I will wait until it fully clears before I ship.