You have to look at the whole system. But as Stu kettle says, a lighter shot load has the greatest effect in lowering recoil.
The RULE in loading shot shells with smokeless is NEVER VARY FROM A PUBLISHED RECIPE. So look through the reloading data bases for what you want.
Having said that, here is a formula that I have used in trap shooting for years, and carried over to CAS until I went to the Darkside;
- Win A-A hulls (Old style- 'cause I have a bunch!) ( R-P RST, Nitro27 or Gunclub are also very durable, and are close to the same capacity.)
- 209 primers of most sorts; - But see the rule in CAPS. above.
- 16 - 17 grains of Red Dot or better still Green Dot.
- AA or Claybuster pink wads for 1 to 1 1/16 oz loads, or grey wads for 7/8 oz.
There are many similar formulas in the data bases, and especially a wide variety of wads. You will find that your game, or clays, or knockdowns will not miss all that expensive shot you will be saving.