What is his problem with RST loads? Too slow, not enough kick, breaks not impressive enough? A 3/4 ounce load at 1200 fps should be a good load for clays. It is a 28 ga. best load which shoots well in the 20, 16 and 12. If he tells you what he does not like about RST you might find another load to meet his needs.
I often adjust shot size more than velocity to meet specific needs when hunting. 1150 +/- 50 fps can kill anything I am interested in shooting with a 20 or 28. If he wants dust on clay birds go with 8 1/2 or 9 Magnum shot. If he wants a longer range load switch to 8-7 1/2-7-6 size shot as the situation dictates. The one true advantage of reloading is the the ten factory choices become 150 very quickly.
I you have a good supply of Fiocchi empties there are a decent number of low pressure, good velocity loads. Same for Federal 20's as well. I loaded a 7/8 load with long shot that was in the low 7k range. Thor's hammer on pen raised birds and worked well out to 30 yards on wild birds.
