Similar to my "22 Special". The action seems to be about identical, mine is more rounded, while yours is more squared.
Yours seems to have a fuller grip frame. Mine is more of a grip stud, so I can tame the recoil with aftermarket grips.
I'm not sure what all that jazz is behind the trigger loop. just decorative?
That doesn't look like a stock hammer to me, unless your grandpa milled those marks in himself or replaced the hammer.
I like your grips loads better than mine. I'll just post links, so as not to hijack.
http://i134.photobucket.com/albums/q...uns/HR22_6.jpg
http://i134.photobucket.com/albums/q...uns/hr22_1.jpg
http://i134.photobucket.com/albums/q...uns/hr22_2.jpg
http://i134.photobucket.com/albums/q...uns/hr22_3.jpg
http://i134.photobucket.com/albums/q...uns/hr22_4.jpg
http://i134.photobucket.com/albums/q...uns/hr22_5.jpg
http://i134.photobucket.com/albums/q...uns/hr22_7.jpg
http://i134.photobucket.com/albums/q...uns/hr22_9.jpg
If the mainspring is weak, I can tell you where to get one. Come to think of it, it may not be a bad idea to get one now, just in case. No telling how much longer they'll be made. (does yours use a leaf spring, or some kind of coiled spring)