In the testing I've done I found that there was very little difference in velocitybetween Pyro P and 777 2F. Which kind of makes sense in that 777 2F is about 15% hotter than Pyro RS and Pyro P is also about 15% hotter than Pyro RS. I found that the difference in velocity was typically less than 50fps and often less than 30fps for equal volumes. I haven't tested a lot of different bullets sizes with both powders but the ones I have checked fell into that range. Give it a try and see what happens.