Iver Johnson, Harrington & Richardson are the first ones to come to mind. Many were double-action, so not leagal for main-match guns in SASS, but OK for NCOWS. Many others, ususally referred to as "suicide specials" or "Saturday Night Specials". Another one (although not a top-break - it kind of "twists" open) is the Merwin & Hulbert, but they are scarce and no one is making a repro at this time, though Cimmaron was thinking about it at one time. Most of the IJ's and H&R's were small "pocket pistols" but I believe some were made full sized. As far as foreign makes, probably the most plentiful would be the Webley, Enfield and Nagant revolvers, but again, they are all double-action, I believe. Hope you can find something that works for you.