I think the question asked IS a good question... I would allow a .22 long rifle class, allow it, but as a separate rimfire class...
I have enough firearms to outfit a small army, of which about 20 are chambered for 22 Long Rifle. The .22 is a viable caliber, well maybe not for city slickers. We sure used the .22 a lot, on the ranch I grew up on.
When it was time to butcher, the lowly twenty-two was used to put a large beef critter, or a hog down, for the butchering. Properly used, the .22 would do the job well.
I would allow all of the interations of the Marlin 39.
I would allow the Wichester slide action .22 rifles up to and including the Winchester model 62A.
There are plenty of .22 caliber Low Walls.
There are many iterations of the Stevens Favorite and Crack Shot rifles available. Varner makes a Stevens Favorite replica, that is a beautiful, high quality rifle. I am fortunate enough to have one of these fine rifles.
I would allow any .22 long rifle ammunition and the .22 WRF ammunition. The 22 WRF was introduced in about 1890.
http://www.chuckhawks.com/history_rimfire_ammo.htmI have read on this thread, those saying the .22 is just too hard to hear the bullet impact. I think saying that is a little too trite...
In answer to that I would say either upgrade the technology, or upgrade the observers, that are having a hard time spotting the hits, or misses, if that is the problem.
Something could be done to the target to record the hits, something as simple as a sheet of plain paper cut to the size, or the outline of the target. I have shot animal crackers and other nabisco crackers, at over twenty-five yards and don't have any problems seeing the hits or the misses. And I am 73 years old.
Bill