Just got back from the NRA and bought some hornady .45-250 grain SST sabots. I had a HELL of a time getting the first down the bore and knew i wouldnt be using them as they were way to tight, i used 80 grains pyrodex rs with these sabots and took my first shot at 25 yards, dead center and 2" high. Reloaded with the same charge but switched to my own cast .44 bullets in a knigh "green" sabot and took another shot, Clipped the 1st shot, reloaded again with the .429 sabot and took another, clipped the 2nd shot. After that i was really happy and swabbed out the barrel with a couple glass cleaner patches and a few dry. Reloaded with the same load and the .429 sabot and moved it out to 100 yards and took my first 100 yarder shot, dead center of the bulls eye but 3" to the right, took another shot and it didnt even show up. Reloaded and let my bro in law take a shot and he hit it dead center and MAYBE 3/4" high of the black dot. After that i went to the truck to warm my hands up, they were frozen stiff and tingling from the cold. After 5-6 more shots i got back in action and was happy with the job the bullets were doing and figured the cold had something to do with the open groups i had shot earlier. When your hands are frozen stiff where they are turning a reddish purple, i think thats when its time to call it quits lol. We went down the road and wet up some steel Pig targets at 100 yards and 200 and were blasting the pigs @ 100 yards and having a blast trying to see how much it dropped at 200. We figured a good 11" drop from 100 to 200 yards. Im going to make powder adjustments and try to get it on sight at 150 and then move out to 200. Those sabots shot great out of the rifle and i was really happy with them. I cant use them for hunting in my state but its great to have them for target shooting. Taking my nephew out tomorrow and let him shoot his first muzzleloader!
Also forgot to mention that the green knight sabots and my .44 bullet loaded easily. Now i just have to give her a bath and mark the sights. i got 100 knight sabots for $13 at a local gun shop. The other Hornady sabots im not even sure if i will use due to them giving me such a hard time loading.
Also got to put my new sights on a real live target and i gotta tell you,Any deer i see this september is DEAD DEAD DEAD! They looked great tucked behind its shoulder.

The SST's are supplied with HPH-12 sabots which are the thickest ones MMP makes. Unless your gun has a larger bore they will be hard to load. But as you mentioned they are not legal so the sabots and home cast bullets will work great for plinking.

I use the regular Harvester sabots with these bullets and they work great - same as the Shockwave. And they are actually legal in Colorado - just not during the designated muzzleloader season. I have used them a number of times during some of the late and dispersal rifle seasons.

Also, I have heard that Thompson Center will test one of their guns, sent back with suspected of accuracy problems, with a 250 Shockwave ahead of two 50 grain Pyrodex pellets. It is their "go to" accuracy load.

Glad to hear that idea worked, Jon! There's a ton of combinations going that route and some very good hunting bullets of cast design that using a sabot will allow one to use. A lot of big bore handgun hunters recommend using the heaviest hardcast bullet a gun will shoot accurately with a big flat nose on the bullet to crush bone and flesh on the way through an animal. Cheap, accurate and deadly...what more could you ask for? Keep us posted!