I have a good buddy, Bill H., that has used a Remington 870, 12 ga. - 3", exclusively for decades to hunt deer. (We are not restricted to a such a set-up. He just choises to use this.) He uses a Hastings rifled barrel. I helped him sight it in. He has a compact Leupold Vari X-III in something like 1.5-6 x 32 mounted on the shotgun with a neat over the top scope mount that is rock solid. He has taken deer cleanly to around 125 yards. Have no experience with 20 ga. slugsters.