Patrick, sounds like the follower is getting stuck. If it's the type of Magazine that can be taken apart then take it apart, run a rag threw it to clean it and lastly add a little bit of oil to it by running a lightly oiled rag threw it. If you can't take it apart try to depress the spring the best you can and take a qtip to add a little oil. I've had the follower stick on magazines before and sometimes that helped. Also when you take it apart make sure it was put together correctly. Hope this helps and good luck.

Patrick, It is definitely the follower binding somewhere on the magazine body. Disassemble the magazine and sand the edges of the follower that contact the mag body and also the sides of the mag body and then retry. May have to do trial and error a couple of times but it will work. Cheers and stay safe!