So I have had this gun for maybe 10 months and been very happy w/ it. At the range two days ago I noticed I could only get 11 rnds in the mag w/o using tremendous force on the top of the Maglula loader. Have read several similar threads but didn't remember exactly which gun and which mags were the problems. After cleaning it today I decided to look into the problem. As best as I could tell, by loading 12 w/o the baseplate on the mag, there was 3-4 mm extra space for the legs on the bottom of the follower so shortening them wouldn't help. Compared the 12 mag spring to the 17 mag spring and they are identical. WOW, what is S&W thinking? Decided to lop off a coil at the bottom of the spring.

When you do that the end of the spring is positioned like the dashed line so it needs to be bent. My automotive experience says you want to twist the wire rather than bend it. So my pliers were positioned so the the section of the spring next to the dark red line gets twisted. Also needed to squeaze the end closed a little. I can now load 12 and that 12th rnd will go down maybe 3mm further when pushed on by the Maglula so it has just enough slop to work freely. S&W really needs to make some shorter springs to go into their shorter mags.