I get good results in a cylinder bore 12 gauge to 30 yards with 80-90 grains of F, three over shot cards 1 3/8 oz of #6 and then another over shot card. Someone recently posted some photos of very impressive patterns using cornmeal as a buffer, so you can try that too if you want to. Reducing your powder will tighten patterns – Less powder, more lead. Shoots far, kills dead, as some period doggerel phrased it.
You might try changing from FF to F. It's slower burning, and you should get reduced pressure and perhaps tighter patterns.
Personally, I’m not going to shoot 2 ounces of shot out of anything unless the gun is bolted down. That’s because I’m a weenie. On the other hand, it seems to me that the more lead you shoot, the more holes you’re going to put in your target.
Is it safe you think?
Now that’s an interesting question. There was a very recent thread in Gun Building on this topic, and the answer is, we don’t know for sure, but it seems to be.
From a philosophical perspective, I like my longbows and I don’t choke my fowlers. But, if some folks want to shoot compounds and choke their flintlocks, I suppose that’s their business. In our culture, we always talk about getting better technology to kill at longer ranges. What if we talked about being better hunters instead?
Other than that, I'm with bob in the woods. I want my patterns to open early. That's because I'm a lousy shot, and I'm perfectly capable of missing a turkey at 20 yards.