Blazer brass 115 gr., Remington UMC 115 gr., Winchester white box 115 gr., all FMJ. Remington UMC 115 gr. JHP, Hornady 115 gr. XTP JHP, and Hornady 115 gr. critical defense JHP all ran great. Ultramax 125 gr. round nose lead is the only thing my Shield just will not eat. FTE at least twice per magazine. My Sig P250 and my Sigma both have 0 issues with the Ultramax and I shoot a decent amount of it so I know it's not the ammo. Between all the jacketed ammo I have at least 1000 rounds through the gun. It feels the same now as it did out of the box, I can't comment on break in. I carry it daily in a Tagua open top belt holster for a Glock 26. It fits great, maybe just a touch (1/4 inch or so) long (the holster not the gun). It works well for me, comfortable, tight, easy to wear under a t-shirt without printing (although my belly helps with this).