I'm not a big Ruger Mk fan (at least the original one with the small trigger guard and the target grip angle), but I did install a VQ accurizing kit on a friend's MkIV. I was impressed with the end result. It can be set for a minimal (but safe) takeup before a light "glass rod" break. As always, I've seen lighter/crisper triggers on other guns. My friend and I meet up every 3 months or so at the range, so I've seen this particular MkIV run a good amount of various ammo, like Fed AM22 (Automatch)/745/510, Rem GB, Win Xpert, Norma Tac22, Geco SA, etc. I have not seen that MkIV w/VQ kit experience any more malfunctions than my Beretta 92 22LR when the same ammo was used. In my opinion, it's more about the ammo quality causing duds (rough handling or priming compound not completely around the rim) than the VQ kit. Others may have different experiences and opinions and that is their story to tell.