Jacky
I'm sure you're well aware that 24 grams ( just shy of 7/8 oz.) is the maximum
charge mandated for 12 gauge Trap & Skeet as shot at the International
(World Cup/Olympic) level, but these typically are at a muzzle velocity advertised as being around 1325 fps+.
These loads work great at ATA Trap, Skeet, Sporting Clays & 5-Stand, and I have used a pant-load of them shooting both white-winged & mourning doves.
Suggest you get the right bar ( not a major expenditure and easy to change ) and do your best to work up a load at around the 1250 fps level.
Although Winchester wads (and Claybuster substitutes) supposedly don't require any wad pressure (only that they be seated firmly on the powder) I have always found that 40 - 60 pounds pressure gives the best and most consistent crimps, whether it be with MEC or P-W presses. (I routinely use
80 pounds pressure on my favourite AA20 ga. skeet/upland loads with WWSF powder)
Once set-up properly, you can get excellent well-formed and nicely tapered crimps with the AA silver wads or the CB0178-12 silver or CB4100-12B white wads for 7/8 oz. loads . It does take a little "fiddling" with wad pressure and final crimp depth (and jockeying the crimp cam back or forth on the MEC) but the results are well worth it.
Stick with it !!!

and oh yeah, about 442 loads out of an 11kg. bag of shot. Almost 2 boxes more per bag than with 1 oz. loads. To keep costs down, you might also want to switch to something like Alliant's "Promo" powder. It's very much like Red Dot in terms of it's performance, and I've had no problems with it ( now some 100 lbs of it later ! ) either summer or winter.
For the price of it, I don't mind a little extra cleaning. After 2500 rounds of these reloads through a new 391 Parallel Target with no cleaning (and no feeding/ejection malfunctions) whatsoever, the amount of cleaning then required ... was no greater than with any other standard powder and/or many premium factory loads.