I shot ATA Trap for a number of years. Singles with a Remington 1100 TA Full choke, mostly. I kept an O/U for doubles because I found the clatter of the automatic a distraction.
I loaded mostly 1 1/8 oz #8, seems like I did better than with 7 1/2. I was working on 1 ounce loads in later days. I even loaded some 7/8 oz 12 ga for the little bit of Skeet I shot.
Shot is so expensive now, the casual shooter had just as well shop Walmart. Avoid the really cheap 7/8 oz stuff.