I'm just now back into ML after being away from it for years and am learning some things. One important thing is that each barrel is different. For example, when I looked for a bullet/sabot combination for my Savage, the recommendation was for 250gr. XTP's with MMP short black sabots. It required a mallet pounding on the ramrod to get them down the tight bore on my rifle. So I went to MMP's 3 Petal EZ sabot because it is thinner, but then the XTP's pushed down the bore so easy that there wasn't enough resistance for good ignition -- 2 out of 3 shots were "bloopers". After trying several other sabots, the one working best (meaning going down easy enough to be do-able, but with adequate resistance) in my barrel was MMP's HPH-24. Of course, that's with a .452 diameter bullet. Less bullet diameter means you will need a thicker sabot.

So, no one can tell you what bullet/sabot combination will work best for your particular barrel unless their barrel happens to be of similar diameter to yours. BTW, when the bullet/sabot is too loose, someone suggested wrapping a slip of paper round the bullet to thicken it before inserting in the sabot. I worked for me, at least when using the very thin cigarette paper for those who roll their own. That way you can use up those too-thin sabots you tried but had to discard.