cur_dog
Lee is correct, there is such a thing as to loose, if the sabot can not grip the lands you will not get the proper rotation, and he is also correct that every barrel is different so you reall nver know until you shoot it. For me I didn't notice a lose of accuracy but velocity went down about 200 fps. The grouped great.
I would not suggest any sabot you have to pound down the barrel, or even need to stand onthe ram rod to get down. I can normally stay with in 2" @ 100 with just about any sabot bullet combination I use from the crush rib to the 24, I can not use the12's because I do have to pound them down, and like I told you beforeI don't even carry a short starter. If you are loading the 24 or regular Harvester with moderate pressure but are getting enough fouling to cause the second shot to be difficult to load - then the "crush rib" might solve that problem.
Were you able to load those .458's that I sent you? Did I send you any .458 sabot/bullet combinations? getting old memory is traveling....