ok so i thought i had heard everything possible in a gunshop. A customer just came in the store, asked for sabots for 9mm bullets to use in his TC Impact. Said that he had just fired some in the last week. I asked if he was sure it wasnt a .45 sabot, He was steadfast it was 9mm. is there any new products on the market justcoming out that is for 9mm in a .50cal muzzelloader. it think the client is full of it, but thought i would ask. You never know.

I got nothin' .  .  .   

yeah. I found a .45-.357 sabot. and .50-40,  but not .50-.357.
(source http://mmpsabots.com/store/mmp-standard-sabots/)
I suppose you could shoot a 9 in a .45-.357 then stick that in a .50-.45...

That is not accurate at all. I had some 45-357 for my 45 ML, and a buddy had his 50-45 with his ML. As is bound to happen on a fun range day. We figured give it a whirl and see. It was hard to get the sabot in a sabot going, and they seem to make the 357 rounds tumble.

Probably for the same reason that a hard boiled egg will spin like a top, yet an uncooked egg will hardly spin at all.  A sabot within a sabot must not be held firmly enough, and is 'free spinning' like the raw egg's yolk.

It was also pretty visible there was some yaw to the bullet as you got it started in the bore. So I assume it all added to the horrible accuracy of the setup.

Would there be a way to mold some sabot cups for the 50 - 357 sabot? I have no clue what plastic is used in the sabots.

I believe then maybe the customer had been shooting a .45 cal instead of a .50 cal. But it is good to know that there are sabots available for the different caliber muzzelloaders.  Now to find them up here in Quebec Canada...