I'd go with the .308 if it shoots straight. Much more effective weapon on deer if it's legal where you live. I use a shotgun because it's all that is allowed.

I would suggest removing the blade though, might not be legal in hunting season. I would check on that for sure.

You might get 90-100 yards out of a smooth bore if your lucky, have adjustable sights and are a good shot. I wouldn't count on it though. A more realistic goal would be 50-70 yards on deer sized game. Where the .308 should shoot pretty good well beyond 100 yards if it's in decent shape and using ammo it likes. This is what many long rang target shooters use and they shoot beyond 1,000 meters.

Not to mention the centerfire will have better designed bullets and cause more tissue damage than a simple rifled slug.

Paul