Favorite in-line bullet/sabot

Not an inline but in my old T/C Big Boar I use MMP 58-cal sabots for .451-.452 bullets. The past few years I have used the same bullet you are using, the 300gr Hornady XTP-HP (not XTP-MAG). I have not been getting great expansion with it at only 90gr of FFg so next year I am going to try some 300gr Hornady SST bullet I got cheap from Midway as blemished. The bullet was originally made for sabots and inline bullets but these blemished bullet came without the sabots and sold for use in 450 Bushmaster, but that's OK since Hornady only make 50-cal sabot for them.

I use 295 grain Powerbelt hollow points.
I've heard a lot on the forums about people who didn't like them. With Powerbelts you have to choose the correct bullet for your powder charge. The standard 295 grain bullets with the green skirt are not made for magnum loads (150 grains). You will have poor performance if you use that combination.

I use this bullet with 80 grains of loose Pyrodex and have killed 6 deer with this combination. Two of them dropped in their tracks and of the other 4, the longest one ran was about 30 yards. I will say, I have never had a complete pass through, every time the bullet was knotted up under the skin on the off side. It has been consistent from the closest to the farthest.

The farthest shot I've taken was the deer in this pic. It was in a cutover right at 175 yards. I was 15+ feet up in a tower stand and the deer was down in a draw. I hit her a little high, but the bullet was angling down and got both lungs.

We did a Special Hunt in a Minnesota State Park this year, new rule was non-toxic projectile.
I used the 451 diameter Barnes Spit-Fire T-EZ, 250gr in a .54 caliber with a Harvester Red Sabot over 100 gr. of 3F Triple Seven.
Did the job on this little button buck, we were required to take Doe's & Fawn's.
I did use my Lyman Great Plains Hunter, not an inline.

AntiqueSledMan.

250 grain Hornady SST in low drag sabot over 100 grains (volume) loose triple Se7en. Deer always DRT. Successful in t/c and CVA inlines for me.

250 Grain SST bullet in crush rib sabot boosted by 120 grains of Black MZ powder.

I found a maxi ball with an overpowder wad and 80 grains of black mz to be very accurate.

Barnes 290 grain TEZ in supplied blue sabot. Loaded over 77 grains (by weight) of Blackhorn 209.

In my Knight and CVA I use the 250gr XTPs and 100gr powder, I buy the bullets and sabots in bulk and it saves a lot of money.