jaybe
I am surprised that the Beartooth has that tight of a barrel and part of that might be the .430 bullet.
There are not as many sabot options in the 44 caliber as there is in the 45 cal. but there is one option. Harvester now makes a new sabot called a "crush rib" if you have a vendor I would suggest you try some of them. MMP is actually making a thinner 44cal sabot for TC but I do not think it is on the open market yet. The last time I talked to Del Ramsey about this I am not sure what the correctanswer was. I am going to follow up one of these days.
http://www.claybusterwads.com/harvester.html
They do make a .429/.430 crush rib
Another sugestion would be to try some .452 (45 cal) 250 Grain XTP's with an MMP HPH-24 sabot. I know that .451/.452 bullets do not have the BC's that 44 cals do but over the short range of an ML they 45 work very well.
http://www.mmpsabots.com/
I do not owm a Beartooth - but I really think that a HPH-24 50 cal sabot and bullet combination would go down fairly easy. The crush rib would again be the thinnest.
I would not want you spend a bunch of money on these experiments but I am fairly sure they would work, and again I would suggest 45 cal vs 44 cal.
I do load all of my guns with thumb pressure - no short starter involved. If you would like to use sabots I think you could. Again going from what I think I know the Beartooth barrel should be an "extruded Spanish Barrel" and while my CVA Firebolt is tight I do use sabots in it.
Good luck - let me know