Deer with a shotgun ?

[antiqueguy]

Your from Ontario, you should know why we use shotguns for deer and not rifles!

and the few times ive been in controlled hunts down here ive used buckshot up north slugs no need for a rifled barrel

 

[antiqueguy]

Controlled deer hunts are only shotgun or muzzleloader so on option to hunt with the rifle!.

yep and I still do see the point for a rifled barrel when I can reach out to 100 yards with a smooth bore and foster slugs ive only hunted for deer in southern ont with a gun a few times buckshot was what I used

 

[TheTooner]

Any recommendations for the length of the barrel ?

Remington's rifled barrels for the 870 are 20 inches. They can be had with either a cantilever scope mount or open sights. I had an 870Express that came with one (w/ open sights) as an accessory. I mounted a 1x red dot and found I was sufficiently accurate with sabot slugs at 100m.

Mossberg also makes rifled barrels to fit the Remington 870. They are 24 inches and a bit cheaper at Cabela's than Remington made extra barrels. I haven't tried one.
A Mossberg Maverick with a 24 inch rifled barrel can be had new for about $250.