it's in the mag itself- i've got a bunch of 5 round springfields that are unreliable like that- more precisely it's either the follower or the spring and my money would be on the spring- if both 1 and 2 were giving problems, i'd say to take the mag apart and stretch the spring a bit, but just number 2 . i don't know- anyway, you need at least 6 mags for the m14 series, all 20 rounders- why, because 1 it's designed for it and looks cool 2 that stupid 5 rounder doesn't give you anything to grab on mag changes( i have to get mine out with a screwdriver after tripping the mag release) 3 they're unreliable
in short, the only reason i have 5 rounders is because kim campbell said she was going to confiscate all the over 5's away back when- if i ever go hunting again or somewhere i have to guarentee my shots, i'll take a 20- or a reliable 5 to keep the c/o's happy- i was told by 2 sources that 1 if they see a mag sticking out of the gun they'll confiscate based on looks alone, then i was told by a c/o that they have a tool ( probably a stick) that they insert into the mag to see actually how many it'll hold- this was after i spent 250 to get 5 rounders from springfield