Hey Scott,
I didn't think it would make a difference, but the Cheddite hulls give me better groups than the Fiocchi.
The card you are using, are they the nitro cards? Do not use cork or fiber wads for fillers, they will give you inconsitant groups.
Yes, I use the pointer on my Mec press for my pressure indicator. It may not be totaly accurate, but if you do it the same way each time, you will be consistant, and that's the important part.
The diference between the Gun Servicing sabots is, they are deeper. Thats why they will take the extra length of the 300gr bullet. If you try to use the BP sabots with a 300gr. bullet, it will swell the hull and it will not chamber in the gun.
I have loaded with the 250gr bullet, with 54gr IMR 4227, CCS gas seal, 2 - 1/8" hard cards CCS sabot with 250gr HornadyXTP bullet seat to 70lb. roll crimp. velocity 1625fps. But not as accurate as the other load. Plus, I like the 300gr. bullet better.
I've also been loading with the 300gr Hornady SST muzzleloader bullet, shoots about 25fps faster and good accuracy, but you can't buy them in bulk. I had to buy them in a 20 pack with the 50cal. sabots. Adds to the overall cost to loading them, at about $1.15 a shot. Plus, you have to be careful that the point of the bullet doesn't stick out past the roll crimp. But they do shoot good.
later......Hank