I use the s3 wad because the s4 is no longer made.You might want to consider a Bismuth Load with 1 1/8 oz of #4's in a FGM Hull ?
It's easy to reload and the pressure is reasonable as I shoot it in my Mod 12's with Tight fixed chokes !
FGM straight-walled hull
29 gr of Longshot
Fed 12S4 wad
1 1/8 oz of # 4 Bismuth
Fold crimp gives 1330 fps / 9900 psi
If you want it to shoot a tighter pattern , add 8/10 gr Buffer !
Just Saying , this load is in the Lyman's 5 th
I’ve also tested a similar load with steel powder about 31grain. My older side by side threw very nice patterns with the steel powder and 1.125oz bismuth.