Tons of guys have had single shot smooth bore guns that they shot slugs out of during deer seasons for years and years. Not a thing in the world new about that scenario!
The largest "weak-link" is the sights. Maybe a notch in the back and a BB up front. But guys have killed plenty of deer with the same setups.
Effective range (consistently and reliably hitting the target) varies. 50 or maybe even 75 yards may not be out of the question.
Personally I'd try some basic Foster-style (pumpkin ball) slugs from Brenneke, Winchester and Federal. See what seems to shoot best for you.
To add to this commit;
I have and still install scope bases, mounts and scopes on many single shot shotguns, especially H&R's. Most will shoot very well out to the 100yd range with a scope and pumpkin ball slugs. If you need help with this give me an e-mail and we can discuss.
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