Your not alone in loading 7/8 oz. load in the 12 ga. To save money, and recoil on your shoulder.
I think you missed my point though. 12 ga. chokes are designed to be used with 1 1/8 payload of shot. Now if you thin out your shot to a one oz. load. Do you need to tighten your chokes to avoid the holes your going to have in your pattern now. So with that should you tighten your chokes even farther if your shooting 7/8 oz. loads. Remember that a 20 ga. optimum size pattern is about 3 inches smaller in diameter than a 12 ga. optimum size pattern of 30 inches. The pattern size needs to be reduced to allow for less pellets in the pattern. Or you will get more holes in your patterns for targets to fly through.
Of course nobody has done any testing alone these lines for target shooters on lighter payloads!!! So if your using skeet chokes for your 21 yard skeet shots on stations 3,4, and 5. How do you know you don't have twice as many holes in your pattern, using a 7/8 oz. payload???
I know if I load 7/8 oz. of shot in my 20 ga. loads and use a skeet choke while shooting skeet. I have the perfect choke for the target distance I am shooting. This has been figured out by years of testing data.
While your light 12 ga. loads might need a IC choke in both barrels??? Or even a Light Modified choke in both barrels for stations 3,4,and 5??? IMO, I think the LM choke would be a bit too much, but the ICr choke should be just right. If that is the case? Then what choke should a person use to break a 21 yard trap handicap target with 7/8 oz. of shot??? Now you see my point. As you remove shot in the payload, you need to tighten the chokes to compensate. Heck, we can't even get shooters to agree what choke to use for 16 yard Trap targets, with a 1 1/8 oz. load of shot. Using less shot, just complicates what choke to use. sigh. break em all jeff