Update. I have put approximately 400 more rounds through my P365 since I first experience a cracked base plate on a magazine. I have 3 flush-base magazines that I keep to the side loaded with carry ammo, and I am practicing with 4 flush-base magazines that I bought in November and December. The magazine with the cracked base plate (purchased in November) developed a new crack in the base plate on the other side today. One magazine (purchased in November) hangs up when ejecting the magazine much more frequently than the others. Another magazine that I just used for the first time yesterday (purchased in December) has a follower that comes out of the top of the magazine body at a weird angle. It has to be manipulated back in place before loading.
There were no malfunctions when shooting, though, and the gun continues to work great. The magazines just seem to be delicate. I have to send at least the slide back to get a new front night sight, so I will try to swap the magazines. My understanding from forum land is that Sig does not stock base plates because it buys the magazines from an outside vendor.
