Twgolf:
Yeah, as Jester said, it’s likely your grip - especially if it happens with multiple/different mags…
If you have “The Flinch” when firing (that last second jerk that causes a lotta people, like me, to hit low-left), then hitting the mag release might be imperceptible…
Thing is, despite our modern practices, a pistol isn’t technically designed for the now-common two handed grip. Thats a relatively recent development. Look at old Army training films or pics and you invariably see one-handed operation. Unless it’s a lefty shooting, the hand isn’t over the mag release.
Try a few one handed (right hand) shots. Or deliberately firing some unaimed shots using a low grip where you KNOW your hand isn’t over anything. That might narrow down the cause.