Well, yeah SGs are only useful for WoE 1.0 castles. I've tanked about 20~~ people on legacyRO using standard reduction gears and aloe leaflets, but ofcourse you'll die to skills like spiral pierce / asura / soul breaker in bragi / magic spamming. Depends who is by the emp when you reach the room
Anyway, on topic..
Western Outlaw is the best handgun as far as I know, and it works well with any skill for handguns too.
Garrison has slightly more damage, but a +4 Western Outlaw does more than a +7 Garrison, so if you have a +7 Western Outlaw you have 15/20 more attack than the +10 garrison. With a western outlaw, you can easily reach 187 ASPD too.