I had the same issue with my S&W 469, the 124MPR at the ogive was just too wide not to hit the lands. The slide would not go into battery. My solution was to use a powder that sat the bullet deeper into the case. I found that Hodgon HS-6 at 6.8 grains sat the bullet for a 1.090″ OAL (published data). I posted a YouTube video on the gun and reloading for it, start at 14.26 where I talk about the 124MPR reloading:
This reply was modified 3 years, 9 months ago by Fred.