There is a difference with the 12 but not as much as one would think IF the data for tapered walled hulls is also used for straight walled hulls. Looking at my IMR reloading manual, 1oz with a Win 209 primer and 15.5 in a Fed hull will make 5700psi at 1100fps. In the Win hull using 16grs makes 5000psi at 1100fps. Now that's not to say every powder and charge will react the same way, but there usually isn't a big difference, and at the low pressures we reload at I don't feel there's a lot to worry about. As we say over at the club - in a 12ga, 15 grains of anything is safe. JMHO

They have been made in the past.

I have 100 new primed ALCAN 10 gauge low brass plastic hulls the only ones I've ever seen. Bought them from a friend several years ago. I'm going to start loading them as I lost all my empty 10 gauge hulls except these in a fire in 2015. No more than I shoot anymore they should last me as long as I'll be around.

The chart states "winlb" as the hull... maybe I'm misinterpreting it?

Maybe it should have been winbl, meaning win black hulls ? Just a guess.