There is much confusion as to the status of short barrelled shotguns today.
If the barrel of any shotgun is cut to less than 18" by an individual or a gunsmith, that converts the firearm to "prohibited firearm" status. So does substituting a short barrel less than 18" long for a longer barrel.
If the barrel of a manually-operated shotgun left the factory (either the original factory or a re-manufacturing factory) at a shorter length, that does not convert the shotgun to "prohibited" or "restricted status". It remains non-restricted. I have a .410 gauge single shot with an 11-3/4" barrel, and two pump-action 12 gauges with 14" barrels, a .223 single shot rifle with a 14" barrel, and a .22 RF semi-auto rifle with an original 9-3/4" barrel -- all they are all non-restricted.
If the shotgun is semi- automatic or full automatic, shortening the barrel to less than 18.5", or substituting a barrel less than 18.5" long will make it a "restricted firearm." Shortening it to less than 18" or substituting a barrel less than 18" long will make it a "prohibited firearm." Replacing the barrel with one over 18.5" long will put it back into the non-restricted class.
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