Sound advice dao. I thought about that striker channel after I typed out my reply.
One thing I also thought to add… Given that the 7 rounder hangs down a bit, on some guns at least, gripping the part of the mag that protrudes (the “extension”) too tightly can cant the bottom of the mag slightly backwards, which simultaneously cants the top of the mag (follower/feed end) forwards. This can both nose down the top round and push the casing rim upwards getting it into the way of the slide as it heads into battery.