Did you fit 1-1/8 oz of steel into a wad made for 1-1/4 oz lead or use special wads designed for steel? I would like to replicate 2-3/4” 1-1/4 oz & 3” 1-3/8 oz steel loads at some point. I figure it might take both special wads & powder to replicate those factory loads.Back when I duck hunted, I rolled my own in 12 gauge, with 2 and 3/4 Fed Gold Medal hulls, 800x powder (not made anymore, but still found occasionally), Ballastic Products Int. wads and 1 and 1/8 oz of steel shot. I currently roll my own steel loads in 16 gauge to use on federal land and other non-tox areas for quail/woodcock/doves with Alliant STEEL powder. You may want to go to the Alliant powder load data web site to look at recipes: Alliant Powder - Reloader's Guide .
Hodgdon powders also has a web site with reloading recipes for their powders, but I've not checked it to see if they have any steel recipes.
The heaviest shot charges listed seem to be 1/8 oz below the factory max. I figure they have proprietary powders & wad assemblies that allow for the heavier payload.As far as I know, special "thick" wads are needed for steel shot (bismuth, being softer, can be reloaded in lead wads) to protect the barrel. Ballistic Products (Shotshell reloading supplies, components, & accessories: Ballistic Products ) and Precision Reloading (Shop Rifle & Shotgun Reloading Supplies | Dies | Bullets | Hulls | Wads | Powder - Precision Reloading ) are the two main sources for steel wads, steel shot, etc. that I'm aware of. There are a number of wads for 12 gauge for a variety of loads. Some powders that are used for lead will work for steel loads (e.g., Blue Dot), but some such as Alliant STEEL have been formulated especially for steel loads. Both BPI and Precision sell a reloading manual for steel shot.