Most likely a deformed chamber.  If you have access to a gunsmith that has a chamber ironer, try that first.  Sometimes dry firing peens the chamber a bit and that makes it stick.  Don't file out that peening, use a tool made specifically for fixing it.   

If that doesn't fix it, might try some very judicious polishing if it's a rough chamber.   

Very easy to screw up a .22 rf chamber beyond repair, by removing material so slow and minimal work is best.  Especially re-read about using a chamber ironer instead of a file.  Many, many chambers ruined by ignoring that advice.

What a beauty
Let us know how the ironer works, sometimes it takes a very light twist or two with a chamber reamer, most of my experience has been with bullseye pistols that needed a touch up. 
Good luck.

The iron tool worked perfect,a couple light twists and case slips in easy and comes right out!    This is a center fire with the barrel clocked to strike rimfire at 6 o clock, I put in a new roller spring also when I first got rifle since it would not go off half the time. Everything works great now,the problem with buying from an auction house.......