Sport45 said it all. Sounds like you are fairly new to the game so it might be a good idea to go buy an additional reloading book. Quite often one manual will list a load with your favorite powder when another doesn't. If it isn't listed in any manual then it is probably a bad choice for that round. I4895 is a relatively fast powder as rifle powders go, so the case size and bullet weight will dictate whether it's a good choice.
By weighing the Fed GM powder, you have only determined how much of Powder X they happened to use. It has absolutely no relation to how much you should use. Commercial rounds quite often use a blend of powders which is not available to the general public. As Sport45 said, you cannot tell what it is by looking at it.