Why 7/8 oz? There are lots of 1 ounce loads for the 12 ga, and these tend to be low recoil. 7/8 in a 12 tends to not pattern as well as one would wish.
I have been out of Skeet for some years now, but as I recall I was loading 1 oz loads with Unique and getting good results. Don't remember the exact load, but wads are available (another problem for 7/8 oz 12 ga loads--you would probably need a felt filler wad to take up space). If you are shooting trap or sporting clays, you will suffer mightily from 7/8 ounce loads in a 12, and your skeet scores won't set any records either.
7/8 ounce loads are great in a 28 ga shotgun, especially for hunting. They pattern well and offer pretty good performance on clay targets too, though they aren't "legal" for 28 ga skeet events. 3/4 oz is the standard load.
There are some softer shooting 1 1/8 ounce loads available if the recoil is what you are tired of. Talk to some of the local skeet shooters (I have lost touch with everyone) and see what they are loading these days. CB
I shoot mostly 1 oz. loads when I'm trap shooting but I do have a 7/8 load. The 7/8 load patterns good with lengthened forcing cones. As far as the wad with a 7/8 load, I can't remember if it is remington or clay buster wads that I use. I will have to look when I get home. Anyways, the space between the shot cones and the poweder cone is longer than the 1 oz. wads. I shoot 700X with both loads.
are you talking about skeet, trap, or sporting clays? or just messing around with clay birds?
FOR SKEET
i have been shooting 7/8 ounce lead for skeet for quite a long time.
powder is hodgon - clays
wad is winchester waa12sl (i do not use a was to take up space. i do not know anyone who uses a spacer)
primer is winchester 209
there are a lot of 7/8 ounce loads recipes in the hodgon book. you can find it online.
i shoot skeet most every weekend and some registered targets. i would say 100% of guys who load their own 12 gauge shoot 7/8 ounce. I have NEVER heard anyone say that they were concerned with the pattern. I have patterened the 7/8 ounce load and it looks/shoots great. A lot of guys shoot 20 gauge for the 12 gauge event. 12's kick too much.
after shooting 7/8 ounce of lead going back to a 1 oz is way too much kick.
I do not shoot sporting clays and do not know what ounce they shoot.
I do not shoot registerd trap and do not know what they shoot. I shoot trap for fun and the 7/8 ounce load for the 16 yard line is fine. But I do move up to 1 oz for greater distances.