Yes you can use 3f powder for large sabots and even large conicals. At least I do it all the time with real good results. You need to rework you load a little as the 3f will produce higher pressures because of the rate of burn. I usually cut the 2f load that worked by 15% and try from there.

For instance.. if I was shooting 100 grains of Pyrodex RS and a 300 grain XTP and getting excellent results, but wanted to try Pyrodex P. I would start at 85 grains and then work the load from there to see where it comes in at.

Triple Se7en 2f and 3f is an area I am not familiar with. I only get the 2f in my area. Triple Se7en the poster would have more information for you on that.

Goex 3f I shoot all the time and like it a lot. It burns cleaner then Goex 2f and I like the way it shoots...

Good luck