Generally it will not be as accurate with a choke constriction. Meaning the best grouping will be through a cylinder bore (straight pipe-no choke) for a smooth bore barrel. The rifled barrels are more accurate yet.
If your asking is it dangerous to you or your gun the answer is no in a modern well maintained firearm. Don't waste money on the rifled choke tubes they're just a gimmick although a fully rifled barrel will be a godsend for accuracy as a good one can place a slug repeatedly into a 4+4 inch bullseye at 100 yards. You will be fine with a smoothbore and modified choke just try to keep your shots under 50 yards but make sure and fire off a couple at that range so you know your accuracy potential.
I've done some experimenting w/ both 20 and 12. in 20 it turns out that a imp. skeet choke patterns better than imp. cyl., and cyl. (rem. 870 w/ truglo slugmaster sights and winchester super x rifled slugs) You can put 3 inch groups at 75 yds. w/ this combo consistently. I find this to be really good for unrifled barrel. Did same w/ the 12 guage down to the choke tube, but accuracy was just a little worse, way sufficient for killing deer out to 100 yds. But, I finally broke down and bought a fully rifled slug barrel and it groups about 3 1/2 in. at 100 w/ super x sabot slugs, but I'm sure you could get better accuracy w/ their higher grade slugs.
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