Something is not right, .22 ammo is far more reliable than that when it comes to ignition. I have several .22 pistols (Ruger MK I, MK II target, S&W Model 41) and a misfire itself is fairly rare. More apt a failure to feed problem depending on the magazine or the style of bullet.
On the round that did not fire did you inspect the rim and observe the strike of the firing pin? It should be substantially indented. On the rounds that do fire inspect them and see that there is no slight bulge just in front of the rim, you want to make sure you pistol is going fully into battery. If it is not and it is still allowing you to fire it something else is not right.
There is no reason for a rimfire pistol to hickup that much unless something is wrong. Even the cheap ammo is not that bad, its the same stuff that gets run by the bucket load thru 10-22's.
good luck GF