At first, I thought that AK was a pretty good choice, but honestly I need a weapon that deals much more damage. I looked and I saw that these 3 weapons seemed pretty good (I can't buy them yet though):
I'm honestly not sure if shotguns are good against bosses, but if they were, then SPAS-12 and Shotty 12 would be pretty good choices. I honestly don't know what to buy. Could anyone help?