WOLFF springs (different than Lone Wolf) shows the 17/17L, 20, 21, 22, 24, 31, 34, and 35 to all come from the factory with 17lb springs - so being setup for .40 vs 9mm from the factory may not hold any water regarding cycling issues with drop in barrels. On top of that I've had issues with S&B 115gr in other factory non-modified 9mm pistols, and multiple shooting buddies at work have reported the same in additional pistols they've tried the ammo in. It's junk ammo, barely good enough for range duty - unless you're real keen on working malfunction drills.