1. Hevishot is 12g/cc, hardly better than most traditional defense lods.
2. ANY large pellet is going to have serious frontal friction issues with penetration in comparison to a smaller pellet.
3. #00 buck is often stopped by a vest, but LEO research that I read was concerned that #9-18g/cc pellets CAN slide BETWEEN the fibers of kevlar and go thru the entire body, as is being reported by coyote, deer and pig hunters in the SE. many little pellets eating their way thru your body before you even realize that you are dead.
4. In a field situation, the small dense pellets were considered surprising in that they were MORE lethal, but went THRU the target completely, while the softer lighter lead #00 stayed int he body transferring the entire impact to the skeletal structure, often knocking the assailant off his feet. At 10 feet, the #9/18s passed all the way thru and left the assailant standing, but with fully macerated internal organs.
I suspect there is little single blind oar possibly even straight clinical testing, much less any double blind work out yet.
To the hand load question, Federal loads some shells in 15g/BBs that would be pretty brutal.
At this point, there is no 18g preloaded on the market and i’ve heard no plans for anyone introducing it. At $8 per shell, the market is pretty small ($5 of material alone)
I bought the gelatin for reasons other than this (tungsten MZ bullet penetration), but this would be a good reason to cook it up…