I can't imagine jug choking being safe in most barrels. The area needing to "jugged" is usually already the thinnest part of the barrel. Barrel wall thickness near the muzzle is often only .020 to .025 . Even trying to make a cylinder choke into an Improved cylinder choke would make the barrel ends very fragile.
If you can show me an example of a shotgun barrel that has bulged or burst near the muzzle, that was not because of an obstruction, I might agree with you. But, you won't, because you can't. The pressures are so low by the time they reach 6"-8" from the muzzle that the only concern with thin barrel walls there is denting. If a "normal" barrel is going to burst or bulge, because of high pressure, aside from an obstruction, it is going to be in or near the chamber, not 6"-8" from the muzzle.
SRH
