I know nothing...
Yet I will add my two cents worth... I had thought about them before I bought a fully rifled barrel for my scattergun. And my younger brother may be, but im not an Engineer, so please if one may view this, correct me if I am wrong.
They may be a great idea but I can't help but think about the slightest "retardation" as in slowing down of.. the projectile, either a sabot and or mores a solid slug of lead hitting those threads/grooves/rifling at the end of the barrel (muzzle) creating an awful lot of extremely instant load of kinetic energy placed onto the threads of the choke and barrel.(the ones that connect the choke tube to the barrel this time)
Simply.. BOOM.. extremely high velocity(in the everyday scenario) then very quickly hitting the stationary rifling after travelling a couple of feet in the least, and being forced into its twist.
it just doesn't sit with me very well, and felt a fully rifled barrel a much more safe and energy efficient method of sending the projectile down range.
I understand its not unlike a projectile "jumping" to the lands in the space between the loaded rifle cartridge and the rifling in a rifles barrel. but I felt it to be awkward due too the distance, perhaps. And I do reload, I also utilize my Hornady OAL(over all length) gauge tool for minimizing the jump to the lands.
I am aware that I may be contradicting myself in my thoughts of the subject, but that's where I am lol, and just went fully rifled slug barrel.
I hope somebody who chimes in may make sense of this, and of course most certainly give you clearance.
Jon
PS- I do realize that im sure they wouldn't sell them if they are dangerous. (then again they do sell cigarettes, don't they)(oh man I contradict myself again, stop thinking so much Jon)