1) Introduce Zip Gun + Pipe Rifle as craftable guns for newbies, 10mm is one of the most available ammo in the game.
2) Reduce DMG of the Red Ryder BB Gun from 8-13 (didn't know BB gun can hurt much as 9mm gun, lol) to back normal 1-3 (argument for start quest is quite wrong, maybe changed for next session, who knows, and anyway you can beat rats even without gun easily as newbie... figure it out), BB Gun is anyway low tier farming weapon, and ones with criticals do fine even with 1-3 DMG (instacrits on certain critters)
3) Just very small gap between 9mm vs 10mm, +2 to max DMG. This need to be tweaked, but yeah very tricky because there is 10mm SMG (and usually have same DMG values, only difference is burst)