When I first realized that such things as singls shot rifles existed, gotta be around sizty years ago, low walls were beneath contempt. After all those decades I am afraid I still retain a strong residue of that attitude - have never owned one, don't notice them at gun shows. I suspect that one reason they get more respect these days is the comparative difficulty of finding good high wall actions. Can't see putting time and money into building a low wall when the same effort put into a high wall will produce a stronger and indeed more valuahle rifle. As for making up a .22 rimfire, start with a Ballard.