I used to use those, but there is no closed compartment for the powder, it communicates with where the bullet goes, so if you have any lube on your bullet, the powder sticks. So I switched to these:
http://www.cabelas.com/product/Shooting/Black-Powder/Loading-Accessories%7C/pc/104792580/c/104701680/sc/104436180/ThompsonCenter-4-in-1-Magnum-Quickshot-Speed-Loader-Per-2/735141.uts?destination=%2Fcatalog%2Fbrowse%2Floading-accessories%2F_%2FN-1100209%2FNs-CATEGORY_SEQ_104436180%3FWTz_l%3DSBC%253BMMcat104792580%253Bcat104701680&WTz_l=SBC%3BMMcat104792580%3Bcat104701680%3Bcat104436180
Not only does it have a closed container for the powder, but there is a "bullet starter" of sorts. Pricey, but you only need a couple of them
