I use a Liberty Mystic X on my G19, 0 malfunctions with full load ammo, the G19 does not like subsonic ammo of any brand or weight, approx 2 FTFs per magazine. I'm guessing a lighter spring would fix the problem, but it's plenty quiet without shooting subsonic ammo.
Buddy submitted Form 4 on 5/20/16, received stamp 2/7/17. I submitted 5/31/16, based on math I should have mine 2/18/17, but based on ATF regularity it might be sometime in the year 2043....