Another thing to check is that all your loaded mags will seat on a closed bolt.
Definitely very important. If they won't seat on a closed bolt fully loaded either modify them so they will or buy new mags. You will be learning to reload with one in the chamber and it really sucks when you pull the trigger and your mag falls on the ground. It happened to a couple guys on the course I was at, they didn't find it very funny, lol.





















































