Yeah, this drove me nuts at first, too.
I agree with everyone, I always use the most conservative data starting out.
Load data changes often, so check the website of the powder makers regularly!
The powder and bullet companies update their data every so often for a very good reason. Power composition has been changed over time, more sensitive pressure testing is available, misprints happen, etc.
Alliant owns Speer, so an up-to-date Speer manual and Alliant data should agree! Speer 13 shows a MAX charge of 14.8 grains for a 158 grain Gold Dot Hollowpoint in .357 magnum, the website shows an identical max charge of 14.8 grains of 2400 for the same bullet.
I don't want to sound harsh, but your manual sounds like it's out-of-date.
Heck, even my book is out of date (Speer 14 is out, I checked, all of my loads stayed the same), but I'm only using Alliant powders and always comapre Alliants current data on their webpage to Speer 13. If they disagree, then I'm using the more recent data. I also have an up-to-date Hornady manual as well, just to sanity check Alliant's data.
Be sure to use the most current data available from reputable powder companies or bullet manufacturers only. Midway USA is a great company for merchandise, but I wouldn't trust them to stay current on load data. Is there a date on the book you received from Midway?
Old reloading manuals are great to learn the process, but generally a poor source of data. Use them as reference material for the PROCESS only.
Also, charge weight will differ by bullet profile. Make sure you're not comparing a jacketed HP to some other style of bullet.
Getting a chronograph is a good idea, too. With a slow burning powder like 2400 you'll note erratic velocity and probably poor accuracy when loading too light. (You might even seen soot around the case mouh from a poor gas seal if pressure is too low.) I don't lean too heavily on a chronograph, but, to me, it's an important tool.
Last edited by testuser; October 4, 2012 at 10:55 PM.