If memory serves back when I was doodling out a couple custom 1911s in college, FLGR's are must-haves for certain hotter loads like 10mm, .45 Super/.450SMC and up. (The .45 Super used an adaptation of the Detonics multi-spring recoil system, which is giving me fits trying to figure out how to replicate it for a 7" Longslide SMC.)