And, yeah, try Sellier.
Went shooting Kadet with some Lapua SV ammo I got for cheap. It was in the tin can and they don't produce it any more. Hollow points with kinda squared tip. Very old can it was. Ammo looked good, tho. And burned exceptionally clean. No residue whatsoever.
While this same ammo worked quite well with old recoil spring came with Kadet (1994), occasional FTF, it started developing fails with brand new original CZ recoil spring. All of them fails. Except for FTF. If it feeded, it fired. Shortstroking after shortstroking. Very annoying, goddamit. Sellier, being quite dirty, on the other hand, worked 100 with both springs. Go figure. At first I thought, my 12 yr old daughter was limpwristing, very fresh shooter she is, but I wasn't, right:) How can grown up man limpwrist freakin .22. Even midget, holding his .22 with two fingers, can't accomplish this.
I don't mind cleaning my toys. To get dirty, first they have to work.
Conclusions - probly mentioned ammo is underpowered or uses very slow burning powder meant for bolt action rifles. Or is just plain old. Lapua is quality brand after all. And recoil spring weight plays much more role than expected in .22LR pistol. And LRN seems to feed better than HP. Ancient original recoil spring is shorter than new (but used couple of hundreds for now) by 10-12mm.