The chamber on my Sportster barrel is pretty 'close', one of the better 'field chambers' of recent .22LRs tried. After the .22CB Short match (a few weeks ago) where about 75 rounds of that were fired through it, the followup .22LRs were hard to chamber. A common 'Q-Tip' wetted in solvent swabbed it out easily and the other end dried the chamber (I keep a few in the travel box for this).
All good after that.