edit: and doh I just realized i posted this under the rifle section, feel free to move it to the handgun rimfire section.
I'm not a huge small bore guy, but I have an HD Military that I got from my grandfather that is one of the pickiest pistols I have ever seen when it comes to ammunition.
The chamber on it is extremely tight. On a clean gun and given a box of regular CCI blazer it will have multiple rounds fail to feed. When it happens you can push the cartridge in the rest of the way with your finger very easily but you can feel the resistance/tightness of it. It's not so tight you can't extract it with your finger nail, but tight enough to cause the gun to choke.
When you remove the cartridge you can see very light scrapes or scratches. However after doing that the round will chamber and fire fine. If I pop each round in the box in and out of the chamber once, before loading it into a magazine it will fire flawlessly.
Was ammunition quality better when this thing was designed or is CCI blazer just shitty .22LR? It's not a mag problem as I know they are picky there too. It will feed fine on the rounds that are not "tight".