Here are some more sabot/slug and loading concepts.

First is Alcan 2.75" paper case with Dixie 600gr slug,
with the side of the case crimped into the relief/lube
groove of the Dixie slug.The groove in the Dixie isn't
quite as deep as the groove in the Fosbury slug shown
in earlier post, but still seems to crimp fairly tight.

Next are various slugs in 12ga REM sabots that take
57 cal slugs and bullets.Those sabots are from the REM
Accutip loadings. In picture you can see one of the
REM 385gr jkt bullets they use. Also is sabot
with 20ga cast Lyman. On right sabot with hardcast 585 cal
640gr lead bullet, the ones I use in my 585HE wildcat
case. I sized it down a little, perfect fit.
Also the .575 cal Dixie Gunworks lead slugs will do.

Also shown is a long pointed 55 Boys bullet in one,
fairly tight fit.We cut back .3" of bullet off so it
fit for length in sabot and is 750gr.

Third are 3.5" brass and plastic with the REM sabot and
the 750gr pointed slugs in them.In all the sabot work we
and others have done, trying to get accuracy and high
speeds together, maybe there is such a thing as too
much plastic. IE, sabots too thick on the sides if doing
50cal or smaller in 12ga sabots, for heavier slugs
at high speeds. Thinner sides may discard more evenly at
the greater pressures and violence of high speeds.
Thin sides may have less give so that sabot grips slug
better to impart spin in rifled use. Example in
smoothbore use is the USS slugs, where the brass slug
is .629" with thin discarding petals that have proven to
be very accurate. And with both reasonable priced sabot
offerings the last few years being undersize, accuracy
problems, etc, maybe time to try something else.

Got to find whole bunch of these sabots. Are these pictured
12ga REMs the only 58cal ones around? I can't find others,
and maybe we can find where these are made. As I have
huge numbers of the 585 slugs, which by the way I think
is best hunting combination, without extremely heavy slugs
which suffer for the speeds needed for longer range use.
It is hard lead, good for big game.And my guy can make many,
many more if needed whether for 585HE rifles
or in sabots if we can find some.ED