This photo was taken one summer at a Christian Camp in Poconos of eastern Pennsylvania. My daughter worked there as a Counselor for kids. The bear probably weighed no more than 300 lbs and did not have body armor.
My Pennsylvania friends seem to bring in at least one bear every year to their camp. Eight guys hunt from this camp in McKean County. The most popular rifle by far is Remington GameMaster slide action in 30-06. But a couple guys hunt with slide action 12 gauge shotguns fitted with rifled barrels.
I speak from experience: Marlin's 30-30 has the accuracy and power
to down game much larger than common black bears. But my friends swear by their 30-06 rifles and that amount of experience can not be ignored.