Sounds a bit hot to me...most recommend using lead alloy bullet data for plated. With HP38 (also known as Winchester 231), I use 5.1 to 5.3 grains of either and get good accuracy. I've never chrono'd the load however. Rod
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5.1 grains of HP38 gets me right at about 750fps average out of my 227 and 220's. That's with a copper plated bullet and thrown on a Dillon 650. Seems like a load that will function most pistols without extreme blast or recoil. Works well in all my pistols.
The old stand-by reply is to use the start load from your manual and then work up to achieve whatever your objective might be (velocity, accuracy, etc). That is still a good idea. The P220 isn't going to have any problem handling the loads listed in published manuals.