How I fixed my SD40 magazine rattle
This is an old post, but I'll add to it anyway.
After studying the magazine without the spring and follower in it, with and without ammo, I decided that the reason it was rattling was because the follower "ramp" side wasn't long enough to reach the loose side of the ammo when in the magazine. When one round was removed, the positions changed and the magazine didn't rattle. I am OCD and want to hold all the ammo it was designed for without the rattle.
I took out the spring and follower and then, using a dremel with a sanding drum, I ground down the area where the shell casing rests which effectively "raised" the pointed ramp side on the other side of the follower. It didn't take much, and after reassembly, my magazine doesn't rattle now at all...no matter how many rounds are in it.
I am no gunsmith, and I haven't shot the gun yet, but I feel like it is a good fix. Would love to hear feedback if anyone else tries it. I figured worse case I would have to go out and buy the Glock follower if I messed it up.
Attached are a couple of pictures to illustrate....