3.5 is actually longer than the recomended barrel for the SB ammo. I carry winchester ranger T's in my M&p 40c. They are a modernized and improved version of the black talons and are considered the best carry ammo for a .40. In a close second i would carry Federal HST's which are very similar to the performance of the ranger T's only without exposing the copper jactets "talons". I know tat four seasons stocks the HST. Most other ammo like hydroshocks is kind of an outdated design
i do carry GD SB in my jframe .38 which is rated the best round for it. i bought this at a gunshop out by wilbraham mass