Decent fitment - TRYBE Defense Smith & Wesson M&P 9mm 4.25in M2.0 Match Grade Threaded Pistol Barrel

It's not perfect but the lock-up is slightly better than the stock S&W barrel. The slide can travel a little further before the barrel begins to tilt. I did not have to alter the barrel at all. It was a complete drop in. The thread protector came with an o-ring. Grouping is roughly the same if not a little better with the trybe v.s factory S&W 4.25" barrel. If you are seeking perfection with your M&P go with a gunsmith fit apex barrel.