Originally Posted By: SWNMHUNTERMy guess would be different guns used in their testing. Reloading books are nothing more than a guide as each gun is different so each guns max load will vary.
+1
Have you ever thought how guys work up loads for wild cat cartridges where there are no reloading reference manuals? I start at the max load for the parent cartrige, load one shot and one shot only increasing my powder charge by .5g at a time till I see pressure signs. I mark the load with the pressure signs and never go to that point again. We have shot a lot of military surplus powder where there is no loading info for at all, especially if loaded in a wild cat cartridge.
Reloading manuals are hit and miss, especially the old ones. Some barrels will not let you get anywhere near a published max loads, while others will allow much more. Different lot# of powder have a huge diffenence in a Max load for your rifle in my experience.
