Just bought some 260 -458 Lehighs. With the cup base what sabot is recommended. Of course I know it has to fit bore.
But smooth sizing? Can they be? With the cupped base?
The main bearing surface is .450 but the barbs are .458 so they can easily be sized down for most 45cal ML bores. I just turn them nose down in my press and run them through a Lee .454 die. You could also use a smaller push rod for maybe a 38cal and resize as you normally would. Never measured the ID of the cup but Lee did sell the punch rod separately too for about $5.
Your absolutely right about the 38 rod.
I haven't had the time to fully look at them. I thought the base was concave. Nope flat area to about .385.
I have a .375 die and was able to use it's push rod in the 45 die. Easy peasy.
Worked like a champ.