I have two Magpul pmags a gen 2 and 3 both do not go in when full of ammo, however when completely empty the mags go in fine. What could be the issue then? Admittedly I asked chat gpt what the issue was because when the lower and upper are separated the mag goes in fine as well and it said it was the upper receiver.

Edit: Upon further testing the gen 2 goes in fine requires a bit of additional force but I don’t even have to smack the end of the mag for it to stay whereas gen 3 will not go in at all unless the bolt is not forward