The sabots work in brass cases .First is sabot in a Magtech brass case,
next to 3" plastic.. In shorter brass it would hold about as much powder
as in longer plastic if loaded like in the picture..
Sabots are about .734-735" with slugs in them, and
the Magtech brass with its thin sides still is slightly small OD at the
top compared to plastic, with sabot wedged in.

Next is sabot in RMC case, and sides are full thickness like plastic cases
at the mouth, so don't expand case to hold sabot. We have RMC make case
mouth ID to fit sabot. Sabot being little over fits barrels tight and rifling
impresses into plastic well and gets best spin, and being tight it leaves barrel
straight, with petals opening evenly. Brass case mouths are tight enough that
we push sabot in with a press.Saves trying to crimp heavy RMC case.

Here is picture of a barrel and barrel on a gun from 20 gauge singlshots that
will have the heavy 20ga rifled barrel in picture, mono-blocked into them.