I tried 10-245 Spit fire's BT's and was glad I did not get the box of 25. I could not get the accuracy out of them as good as the 300gr L-N-L Hornady Sabots behind 3-50gr pyrodex pellets in my T-S,ST-Encore. The 245gr Aero Tip P-Belts I tried of my friends were more accurate Also. But the L-N-L were grouping in and right around a circled in quarter that my cross hairs all most completely covered at 100yds-T/C 1x32 scope. My friend's get expansion out of there P- belts using the aero tip's 245gr and 295 grainer's on deer and elk. I got great expansion out of the Hornady on my 4pt this last Oct, or may be should have said I hit it behind the left front shoulder and left an exit hole 3inches in diameter on opposite side through the ribs. Just over 223yds metered with a Bush-800yd R=F was really pleased with the accuracy of those Sabot's and gun. Had the gun for 2 yrs and this was my first year I decided to go Muzzle Loader hunting instead of Rifle.

Let's see if I have this straight. The .50 cal. powerbelt bullet goes completely through an elk, and doesn't expand. OK, whats the problem? It seems to me that a 1/2 inch hole going in, and a 1/2 inch hole coming out is just about all that can reasonably be expected. Just how much expansion does a .50 cal. slug need to do its job? I for one, would be very happy with this type of performance. A "mere" 1/2 inch exit hole should leave a pretty clear blood trail, if you happen to need to follow the animal. However, I don't think much of a trailing job would be needed if the slug was put in the right place.
Just my opinion, I may be wrong.

Tweesdad, I'll second the motion !!

While I have never recovered a powerbelt from the elk I have killed with them, all have been one shot kills thru the lung area. Entrance holes were 1/2 inch, and exits were around 1". I use a 50 cal TC ML with 348gr (hollow point) powerbelts and 90 or 100 grains of Clear shot. I have been well satisfied with this combination.