I made a brass holder out of rubber fuel hose to help me hold my 223 brass. It works great and is much easier to hold onto than the brass is. The fuel hose brass holder is larger and is easier to grip, the rubber really hangs onto the brass so you don't have to squeeze nearly as hard to keep the brass from spinning.
I used 3/8" fuel hose and cut it about 3" long and then slice it twice down the center about 1-1/2" deep. So there are 4 slices halfway down the length of the hose.
Then I glued a wooden plug in the end without the slices so about 1/2 of the 223 Rem brass will be sticking out of the hose when you push the brass in against the wood stopper.
Then I wrapped electrician tape around the whole hose to keep the sliced end from separating.
I only use this brass holder when doing the primer pockets on military brass.