i have a remington 870 express mag turkey gun(3 inchers only..) though its only a 3 inch mag they still kick...and the gun is a tuny little guy...21 inch barrel and i dont think it weighs the 7.5 lbs they claim...id give it 6..maybe 7 tops...i thought it would beat me hard shootin 1 7/8oz of shot out of a 3 inch mag..i braced my self for the shot and thought the gun never went off!...it kicked but not how i expected...i liked it more than my mossberg 500 shooting the same loads but with a 28 inch barrel and the gun weighs atleast 9 lbs or so....you may be surprised...id brace for a mule just so i didnt seperate my shoulder or anything jsut to be safe..cant fly fish with a shoulder seperated! lol
good luck with the new toy!