First clip of the factory spring is at 7 turns, if you don't like it that stiff, do what i did and cut off one more turn, finishing with 6 loops of spring. Finish the bottom turn so it can be reinstalled in the lower magazine insert.
With an .054" drill, slightly smaller than the diameter of the brad nails I'll use for pins, spot and drill pin holes through the magazine floor plate....transfer the holes to the magazine body. I drill through the front rib section and about the same distance in from the rear of the mag. That'll clear the locking tab in the middle of the lower insert.
Chuck a brad in the drill and ream the holes in the floor plate and mag body to a snug fit. As you can see, its a good idea to file in recesses on the bottom side of the lower insert. About half way through is plenty, helps get the brads started when you have it all together under spring tension.
The back end of the upper follower, set up for automatic rifles, e.g. bolt hold open. Don't need/like it that way, I want to be able to close the bolt on an empty mag.
Short work with files, sand paper and some 0000 steel wool rounds over the back of the follower so the bolt head can push it down and out of the way, thus allowing closure of the bolt on an empty mag. (I've had an open bolt fall out walking out of the woods.....it can't fall out if its closed....and if the empty mag is inserted in the gun, I won't loose the mag out of a pocket .... again....)