Yes, if it's gummed up and not letting all the force from the hammer falling go into the firing pin, the resistance could keep it from hitting as hard as it should. Gummed up stuff around the chamber might be keeping the round from fully chambering meaning the bolt won't close all the way...
That would be where I started, a detailed tear down and thorough scrubbing and lubing, it's a 22 it's been shot often and put up .....probably just needs a deep clean
There ya go then.....drill that ***** out then take a small jewellers file and chamfer the edge going into the gas block so alignment isn't as critical
If it works outside the upper.....actually put the upper together....what MAY be happening is the barrel is sliding forward JUST enough to keep from locking up.
Often times it's cheaper to sell the current barrel and use that money to buy a new one in comparison to having the current one turned down and reprofiled.
But you could call Nate at Ft Daniel in Lawrenceville.
If you do send it out, remember to include your gas block and barrel nut, once...