I'm pretty sure this has already been done by others but I thought I'd share my experience.
I found a couple of Winchester AA HS .410 hulls at the range so I thought I'd do a little experimenting.
First, I cut them back to 1.7" which is just under the cylinder length of my NM Blackhawk. Next I removed the crimp sleeve and adjuster from my Lee 45acp factory crimp die and resized the brass portion. I'm not sure this actually did much but I thought it was a good "just in case" step. I then punched out the spent primer and re-primed with a Winchester 209. I found that using a magnetic bit driver type screwdriver worked pretty good for repriming. With the bit removed of course, it fits perfectly down the hull and allowed me to just push the hull and primer down flat against the workbench to seat the primer.
Next I weighed and charged with 5.0gr of Bullseye. For the over-powder wad I used a cardboard wad cut with a sharpened 40 S&W case. The wad fit the hull perfectly and that same bit driver screwdriver pushed the over-powder cardboard wad down flush on top of the powder. Obviously, I did not compress the Bullseye charge, I just sat the cardboard wad on top of it.
For the shot charge I filled the hull with #9 shot and then poured it out and weighed it on my scale - 217.2 grs. Just a touch short of 1/2 oz!! I was surprised and somewhat concerned about my choice of 5.0 grs of Bullseye. But, I figured this was going into a NM Blackhawk that spits out 30k psi Ruger ONLY loads so 217 grs of shot pushed by 5.0 grs of Bullseye should be well within safe limits of the Blackhawk. If you try this yourself I'd suggest a lighter Bullseye start charge or a slower powder with slightly less shot, maybe Unique? As always work up your load.
For the over-shot wad I used the same sharpened 40 S&W case and cut a plastic wad from the lid of a cottage cheese container. Once again it fit perfectly and a bead of super glue gel held it in place nicely.
The finished shot shell round looks pretty decent in my opinion. Here it is compared to a 45 Colt 250 gr LRNFP:
They do fit snug in my NM Blackhawk cylinder which has been reamed to .4525 for shooting cast boolits. I have to finish pushing the rounds into the cylinder when they encounter the throat of each chamber. But, the force required is mild and by no means what I would consider forcing it. With that said, these may be too snug for non-reamed cylinders and most likely too long at 1.7" for anything other than the large frame Blackhawks.
I did test fire one round at 10 feet out of my 4 5/8" bbl NM Blackhawk. The recoil was mild, no signs of excessive pressure, extraction was easy. The pattern at 10 feet was pretty impressive in my opinion. By my calculations you're putting around 362 pellets of #9 shot on target.
I just thought I'd share and as always, attempt this at your own risk!! These are my results only and YMMV. I'm not responsible if you do something silly and hurt yourself or others!!
TC