Those are pretty cool. I thought it was a whistle at first but the cutout is on the wrong end for it to work. Hard to tell from the pic but I assume they are brass being shell casings? You may need to use 2 different types of media though, one for deburring & another for polishing.
I use coarse ceramic mainly for a stoned wash finish on grade 5 titanium but it deburs fast as well. I use a combination of v-cylindrical & triangular. Coarse cermaic would not be the right choice for those shell casings. I've used the coarse ceramic on aluminum & it gives a bead blast appearance. The coarse is fast acting so I only tumble for about 30 mins. Extra fine ceramic is used for polishing but I've never used it & can't say how it works. I suspect it won't get out all the fine scratches.
I use plastic pyramids for deburing aluminum. I let it run overnight. The coarse ceramic will debur fast but I don't like the result. I also have green rouge impregnated walnut that I use for polishing as well as corn cob. These media work very slow, they don't debur well & not at all on harder metals. I've never used the corn cob, I got it for free with a small tumbler I bought used at a gun show. May want to check with the reloader guys, I believe walnut & corn cob is what they use for polishing