Moe,
As already pointed out, they are supposed to be hard to START but they load easy after initial resistance, in a clean bbl. Some folks have reported carrying them all day on a hunting trip only to find they have slid forward a bit in the bore which is NOT a good thing.
In my experience, they are a GREAT choice. Some years back, I pulled the original 1:48 twist bbl. off my 50 cal. T/C "hawken style" rifle and replaced it with a Green Mtn. Drop-in to get better results with patched round balls. I've enjoyed that set-up, killed some deer with it and have nothing but good things to say about the choice I made. That said....
Couple years ago, I dug the old bbl. out, "just because". I had a set of "fire sights" put on it and began testing a variety of conicals. After a lot of bench shooting of 6 different products, using various powder charges with each one...I settled on the Hornady 385 Great Plains over 90 gns. of Goex. Installed on my T/C stock, it is my Go To "Hog Rifle" for hunting in S.E. Georgia. In that area, I'm hunting from a fixed stand so the rifle doesn't get jostled around all day. I've checked...and never had that "issue" with the bullet coming off the powder to be occurring.
Performance on game has been perfect.