In jug or normal choked 12 bore, I used 3 dram measure, which is 82gr. That powder measure holds just a tich (1 or 2 pellets) over 1 1/8oz.lead shot. That is a typical load, in my opinion for a 12, for upland birds.
If I was using a cylinder bored 12 bore gun for turkey, I'd be inclined to use something like a 100gr. powder measure which holds 1 3/8oz shot.
A 110gr. measure holds 1 1/2oz shot.
A 120gr. measure holds 1 5/8oz. shot.
Commercial stricken powder measures, adjustable or not, may or likely may not throw these powder charges. You need to weight them. Lee Valley Tools sells a pocket-size electronic scale for $20.00.