not to step on toes but a 330 on a damn is iffy at best ... will get alot of fired traps due to beaver carryin debris to work on the damn .... explain the situation a bit better .... do they have any channels cut into the timber ??? swamp land?? may help if ya tell me what state ya in too ... have trapped quite a few states .... but what im tryin to say is ... every situation calls for a diff method ... do ya have access to #3 - #5 footholds?? .... 3/32 snares ??? 330 conis ?? ..... i have shot alot of beaver with .22 mags tho .... make sure ya check ya regs before doing anything at all ...would hate to see ya get fined for killin a dang beaver !!