I had good luck with the +1 extra thin followers from Taran Tactical and a Grams 11 coil spring. Had to shorten the back of the follower to be 29.5mm to fit the p10 tubes. Then had to shorten the underside of the follower a bit. Then put a new side hole in the underside of the follower for the spring to attach to it.
Did also tune the mag body by squeezing the neck / base of the tube transition area together a bit to get a better single file stack at the top to keep the top couple rounds more pointed up. I will also be filing the ribs inside the bottom of the tube a little to allow more room for bullets to stack down there. I have an easy .200" now to compress with 23 in the mag.
First picture, I had to trim I little where the orange arrow is to center the follower on the spring. And once I did that then I drilled a second hole by the red arrow to connect the follower and spring.
Second picture, I had to sand the bottom up a little but also by the back blue arrow I took material off until I was at 29.5 mm( orig 31.75mm). The red lines show the 29.5 mm dimension.
Lastly, I bent the follow and the first couple coils to be pointing up in the front a bit more.