Throwing a large fly should generally use the term of shooting not casting. Here is my take,
Casting: throwing a long line with multiple false casts.
Shooting: throwing for distance with normally only one or two false casts.
Every time you false cast, you use the body strength of a cast; keeping the false casts down to a minimum means more fishing before you get tired. Shooting a longer line means you can fish more water with less casting. More line on the water is more time between shooting and allows your body to rest more. All these things add up to a less tiring day on the water. As we get tired our casting/shooting falls apart and I find I get more frustrated with timing and distance issues in my shooting.
I run a ten weight pike taper on my 8 weight Axiom/TiCR x. I only shoot so it doesn’t over weight my rod. I could never cast this large of a line. The larger belly allows me to throw 10 inch or bigger flies 70+ feet with one false cast all day long.
Here is the process. Lift the fly off the water with close to half the belly still out of the rod. Make a large haul like you are throwing a backwards cast and use the water to load the rod. I lay the rod against my forearm to help create an anchor point. On the back-cast you should be feeding line. This will normally feed enough line to clear the belly through the guides. Now the forward cast has a full belly to shoot properly.
Since the line is a ten weight it also has a larger mass to over compensate for the larger fly. You really do not feel the larger fly on the line as much as you do with an 8/9 line. This helps to make the rod feel better in the loading and casting as well.