I would like to think if you know the velocity & BC of the round your using, plug that information into a ballistic program and you will have your answer. At the very least you'll be close enough. Ballistically I think you should be able to hold dead on and still be within a 8" vital at 20 yards especially if your shooting a premium round. I like the Hornady 2 3/4 SST sabot, they have been fairly accurate out of my Moosberg. 100 yards is generally max distance for any rifled shotgun and I have mine sighted in to shoot 1" low at that distance and been able to hold dead on at any distance right out threw 100 yards. But thats my combination and not yours so your results may not be the same. If it were me I would do like isnipe suggested and break down a buy a box to find out for sure. I certainly wouldn't get the green light from anyone and go hunting without being absolutly possitive how my shotgun shoots. That would be the ethical way to approach this, I don't know maybe it's just me!