Barrel appears to be walking out?

[sheepherder]

Originally Posted by DonVoigt

I believe you would best be served by purchasing a barreled receiver(upper) and retiring the one shown.

Yes on the new upper for center-fire shooting; but this upper could be re-configured for rimfire/.22 shooting.

It could have a plug silver-soldered/brazed in place and bored out to take a .22 replacement barrel. There have been several .22 toggle-trains for sale in the last year.