Firstly I agree with all of the above.
Seems to me that you have poor gun fit and that needs to be rectified first. I shoot trap type stocks for Sporting....and game, as I find that with drop at the heel the gun lifts into my face......and mine is very pretty and needs TLC I can assure you.
However, as per your initial question above......You need both Shot Density and Kinetic to break clays. I can iterate on here that I know lads who shoot long range stuff with 24gram 7 shot shells at range and hit the same as I would with 28 gram. I can go on about busting chondels at Sporting Targets with 8 shot at 80+ yds, but can also remember hearing 8's ping off trap targets at range..... :wacko:
I'd give Fblack Sporting 8.5's a dance in 28gram and then fblacks 24 gram in 7.5s a look. The wads in these pattern very tightly (in several guns I know), and the recoil feel (although subjective) is easy on me (personally)
I shoot mainly 8's as I get my best breaks at normal sporting distances with them i.e. 60m. But when you see a rabbit clay being thrown at 70m off a hill or quartering (I have...[plenty of times), then big balls and tight chokes are needed to GUARANTEE a break! I shoot probably 80% 8's and pop in a tight patterning 7 for long stuff. Will the 8's break out there???.........yes.....I have done it.....lots.......but when every last target is required on the card to get a score.......you need to be sure in your own mind that you are putting something in that will break the target EVERY TIME.......and having patterned F-blacks against other shells......they are so tight in my gun that I know they will do their stuff out there.
Hope this helps!