This requires a shield arm 15 round steel magazine(s) and a $20 replacement Shield Arms steel mag release button. I did this with simple tools I already had and about 15 minutes of my time. The mags fit flush with grip and no extensions! Keeps it compact with 5 extra rounds

I'm posting a video because though it's really simple, it requires some finessing and both hands, so no pics except the tools I used and my pistol below: I used a plastic punch to reseat the mag catch spring all the way down.
Video: https://www.youtube.com/watch?v=pbSNT0zzug8

https://hosting.photobucket.com/1332...320&fit=bounds