nkhunter
Ease loading is really dependent on the size of the bore.... You need to find a sabot/bullet combination that goes down your barrel with some snugness.. if it is to easy you will loose velocity and possibly accuracy...
MMP make 3 actually four different thicknesses of sabot... the forth is the old standby black petaled sabot used in larger bores and suggested for the Savage to keep from blowing out with smokeless..
MMP Sabots... .451/.452 - 50 cal Black Sabots...
HPH-12 -> is the thicker sabot designed for the larger bore 50 cal rifles..
HPH-24 -> is slightly thinner and probably the most widely used sabot for 50 cal rifles..
The 24 is comparable to the regular Harvester long petaled sabot - Harvester also make a short petal black sabot
HPH-3p-EZ -> is the thinnest of the 50 cals and loads easily in tight 50 cal barrels
This is comparable to the Harvester "crush rib" sabot...
I have shot both the 3p and the 'crush rib' - can not say say there is a lot of difference in loading effort. Although I personally like the results of 3p better.
Remember you really do not want to use these thin sabots unless you really need them. If the 24 or regular harvester load with some effort - you are better off using it.