Quote Originally Posted by browningautorifleicon View Post
Our laws require 5 rds for a carbine and I too have done scads... I use steel strapping bent into an upside down "U" so the flat is against the follower. The legs run down the outside of the spring and the whole thing lies about three coils of the spring from top. I also found all mags a bit different, you couldn't assembly line them or you's get some that hold six rds. The top coils of the spring are integral to the whole deal. It's like the Colt factory block for their 20 rd mags except upside down to them...

It takes time but when they're done they all feed perfectly.
When I purchased my Colt SP1 AR15 in 1971 it came with 2 twenty round magazines that were blocked to 5 rounds for hunting purposes. There were instructions on how to remove the blocks. I understand that later on Colt pinned the bottom of the magazines so they couldn't be removed.