There was a intermittant \'failure to extract\' on different barrels, a magnifying glass showed the problem. If the 22 rim was sufficiently smashed by the firing pin it would \'catch\' on the brass coming out with the extractor. Check the barrel/brass mating area segment where the firing pin hits, its more critical there.
Very slight out of concentricity between firing chamber rim counterbore and brass.
After cleaning up the brass all ran smooth with no \'failures to extract\'.
After the dremel work I scrape and polish the area up. :roll:
The extractor, being on the top, will pull the empty out and force the rim \'downward\' so check the groove bottom for \'hang-ups\' as well