Rimfire gurus... What is/was the issue with my 10/22?

I have been customizing a newer run of the mill 10/22. In the original configuration it shot all ammo I fed it, even the crappy Remington Golden Bullets. When I switched out the barrel for a Shaw stainless steel bull barrel the problems started.Tons of failure to fire with the GB, better results but still the odd failure to fire (1 out of 50 or so) with CCI mini mags. Even went the route of putting in a KID custom bolt with the wire cut firing pin. When the gun did shoot, it was very accurate, as good as a Volquartsen which costs 5 times as much. But those persistent pesky FTF cost me big time during Action Rfile competitions. I removed the barrel twice just to make sure it was seated all the way in and tightened the 2 barrel screws pretty well.

Today I did a test to see if its just the Shaw, put in the original skinny Ruger barrel and low and behold, the gun shot every brand of ammo i fed it, incl. the GB's which were terrible before. So the big question is... is this a headspace issue? Something I can fix? Or just forget it as I really don't want to pay a gunsmith hundreds to fix this issue?