So I assume your shooting a remington. Here are a few things to try. First use a good follower. The hi viz plastic follower work a lot better than the aluminum followers.
Depending on your extension it may come in several pieces. Make sure the nut/collar is screwed down snug first. Then screw down the tube down snug. This will align the tube where the follwer will not bind.
There are also edges and stuff that can be rounded off but I let Rob melhorn handle that. I had simlar problems as you but Rob took care of them and then schooled me on the follwers, collar blah blah blah.
Hope this makes sense it's late and I've been drinking again.