I think the sb was the smooth bore, they offered four main versions of the 510. The standard profile barrel, a target model that came with better sights, the smooth bore, which was a non rifled 23 caliber bore for use with 22 shot shells and the rutledge bore. I figure the rutledge was like an overbored shot gun barrel, supposably lets the shot stabilize while its still in the barrel. Notice that there is no rear sight, or even a place for it, just a gold bead on the barrel. I bet this thing would be a hoot in a corn crib. Found a real cool site
http://www.rimfirecentral.com/forums/index.php
, now all I have to do is find the other versions of the 510, this "cheap little 22" is going to cost me. BTW, I found a 510 liek this one on some kind of antique firearm site priced at $980, any one want to spend $980 on a 22? Better yet, I'll make ya'll a deal and let it got for only $900
