If you prefer a lead based bullet for sabots, these Fury Star tips are a bonded bullet and come in sizes from 250 to 275 to 300 grain. Being bonded they will not come apart when they hit meat and/or bone, like XTPs can. Very good weight retention.
https://www.furycustombullets.com/shop-2/smokeless-muzzle-loader-bullets/452-star-tip-mz/
At the .452 diameter Furys they are right on the line where you may need a crush rib or a standard black sabot. Gun’s bores differ some in finished diameter but one or the other of the sabots would work with this bullet.
I’m going to be using the .40 caliber, 225 grain version of this bullet in my smokeless muzzie and will be pushing them at roughly 2400-2500 fps. Even at that velocity they will not come apart.
Both the Barnes 250 grain XPB and this Fury Star tip at 250 grains can be moved along at about 2100 fps with a 120 grain [by volume] charge of BH209 or T7 3f, which will be about max for both powders. At 110 grains in volume of either powder you’ll be moving the bullets right around 2030-2050 fps. Your best accuracy will likely fall somewhere in between a charge of 100 grains by volume and 115 grains by volume of either powder with the 250 grain pills and a black sabot.
I should note here that the Barnes XPB in 250 grain .45 cal is not available right now and hasn’t been since this time last year. A 225 grain in .45 is available and is identical to the bullets in the picture except for diameter. I’ll be ordering a couple boxes of the 225 in .45 for my Accura because I do not have a lot of the 250s the gun has hunted with. I’ve shot the .452 225 grainers in the Accura and they are really accurate with a 110 grain by volume charge of BH209 in a black sabot, just never hunted them in the long gun.
There are excellent bullet options out there, but they are spendier than the XTPs and likely a mail order product. In addition to thew Fury link, Muzzle-loaders.com, midwayusa.com, and grafs.com are some vendors that handle the Barnes bullets along with the Barnes site that probably has the best size offerings/pricing.