Originally Posted by LDBennett
The Hornady 6th Edition lists the 180 grain XTP 44 Mag in a Ruger Blackhawk using 2400 at a max load level of 26.6 grains for 1550 FPS. Your load of 22 grains yields 1300 FPS.
The Hornady 4th Edition lists the 180 grain XTP 44 Mag in a Ruger Blackhawk using 2400 at a max load level of 22.1 grains for 1500 FPS.
I notice that the 110 load levels vary a lot too whereas the other powders are pretty much the same.
One explanation may be that over time more loads have been tested using more modern and accurate pressure testing methods and updated in the latest edition. In general, when a new manual comes out you should buy it and rely on it rather than an older edition.
When there is a disconnect like this the latest manual is the one you want to use. In this case I might contact Hornady and see if they have an explanation for the huge 4 grain discrepancy or perhaps to tell you the 6th edition is wrong (???).
I respectfully disagree. You should throw your Hornady manual in the trash can. I have never seen such gibberish in my life. While I agree pressure equipment has gotten better but accurate measuring of the speed of a bullet has been around a long time. One book showing a max load of 22.1 grains going 1500 and another showing 26.6 grains of the same powder, same bullet and same gun only going 1550 is the writings of an idiot.
I have had the same experience with Hornady on other pistol and rifle loads so I trashed my Hornady manuals. Another thing powders like 2400 being measured in tenths should also tell you something about the author of the manual. A half a grain of 2400 one way or the other is no biggie.