The citation from the ORC, in bold below, was sent out by a regulator when we asked what would be legal to shoot in a fully rifled 410. As said before, cannot be an all brass cartridge and no
neck turning,
correction, "no necked down cartridges", not neck turned. Nothing regarding OAL or bullet proturding from case. Nothing regarding jacket bullets, which shouldn't be an issue since lots of folk are shooting copper sabot slugs.
As Catfish said before, the plastic hull will limit the pressure and velocity. It looks to me like the best you can get is velocity approaching a starter load for a 50/45 sabot load in a 50 cal MZ. As for accuracy, I have one load that a got a 2" group @ 55 yards. I am still working on what powder and how much, not really looking for the most accurate load at this point.
Trying to make this shotgun is a fun project, but there are lots of fully rifled 12 & 20 ga slug gun/ammo combos out there that would easily outperform what I am working on, however the gun, so far, is very recoil friendly & a major improvement over 410 slugs available from commercial sources, except maybe HBBS.
BB
1501:31-15-11 Deer regulations
(C) Hunting implements
(2) Firearms;
(a) It shall be unlawful for any person to hunt or take deer with any firearm except:
(i) A shotgun no larger than 10-gauge or smaller than .410 caliber firing a single projectile per barrel.
It shall be unlawful for any person hunting deer to
use any shell casing which is necked down or made totally of metal
for any of the shotguns listed