Do your mags seat properly with the slide back?
Do your mags seat properly with the slide back?
My P9 does have the grip rounded off tapering toward the back. Yours looks to be a little uneven in the photo. But that's just a minor external flaw that really doesn't matter as far as the function of the gun. I really doubt that the mag well is off center. And no, the offset feed ramp doesn't require any offset in the mag well.
I would be very careful about sanding off the base plates. The Kahr plastic mag base plates are on the thin side as it is. I had one fail at the groove and dump out all my rounds once. Admittedly, it was a very old mag that had been carried for many years. I replaced all my plastic 9mm bases with steel, but I see that isn't an option for the P45. Have you tried using a 1911 mag? I have read that some 1911 mags work in the P45.
My CW45 (bought new about 3 years ago) has similar beveling although it's even. Is the gun/magazine new? A full mag pressed into a closed slide gives a lot of tension and care must be made to make sure the magazine is seated properly (such as when chambering a round, topping off the magazine, and reinserting). If you don't pay close attention to this the mag might not be fully seated and can pop out when firing. I noticed this issue when everything was new, but not so much now. However I still pay attention when topping off. This shouldn't be an issue with the slide open, i.e. when reloading from slide lock.
I don't know if it reduced this occurrence, but I've since had my mag release button coated which might have aided in this issue. I had my Kahr carry guns' mag releases coated because they were showing signs of rust after carrying in the summer.