FWIW, I just recently went through the P365, MC9 Prime, and FN Reflex XL trade off. I choose the FN. Took it out for its maiden range trip yesterday. 200 flawless FMJ rounds from 4 brands went through it. 11 HP rounds fired and cycled perfect.
It received a through cleaning with alchohol, a generous more than normal oiling, and roughly 200 slide racks and dry fire prior to the range trip. The magazines were fully loaded, unloaded, and reloaded every day for about a week prior to break in their springs. Ammo was not run through the pistol for the magazine unloading. This process has been 100% successful for me with all new acquisitions.