I have Version II and a Version V of the reloading manual. (Yes I've been loading a long time) Manual II shows a TWO grain difference in the max load on the caliber I was looking up with the II being higher. Called them today and they said the component (powder) had changed that much between the two manuals. The powder has been made for 70 years and I think the only thing that has changed is the litigation. They assured me that had nothing to do with the change. I'm calling on that. I'm going by the older manual and using the usual precaution on pressure signs. Your thoughts........

Don't have my Sierra manual in front of me. What does it show as max charge for 175 SMK being pushed by H-Varget? Hogdon shows 45.0 gr as max I'm pretty sure Sierra is significantly more conservative.

Where do we send flowers?

Most of the B.S. about velocity doesn't matter much if you are
shooting a good projectile and put it exactly where it belongs.
Many hunters are so tied up on velocity that they forget it's the
bullet that does the job in the end..Don

but,but,but that where the fun is else we would all be shooting 30-30's !

I agree with comments about changes in powder changing the charge requirements in more recent manuals. I also think recent manuals have become more conservative in our litigious society. I think there is another factor that is being overlooked in this discussion.

Most of the old load data was developed using CUP (copper units of pressure) pressure data. CUP pressure readings are basically measuring a crushed slug of copper from a hole in a test chamber. There is only one measurement, the slug is removed, measured and the CUP pressure is given.

Modern data uses PSI (Pounds per square inch). A gauge (electronic) is hooked to the test chamber and the cartridge is fired. As electronics have become more and more sophisticated, pressure readings have become more and more detailed, allowing for numerous readings over the milliseconds of the cartridge firing.

As the readings have become more sophisticated and detailed, my understanding is that many loads that were believed to be safe showed very brief, but very disturbing pressure spikes that have caused many of the old "safe" loads to be deemed unsafe. What has disturbed the reloading industry even more is that this has not been a 1 time event - as the equipment gets better, more disturbing spikes have been found in loads that had already been reduced from previous "safe" loads.

The upside to this is that the quest for safer powders is leading the industry to better powders. Powders (and powder coatings) developed to reduce and/or eliminate the pressure spikes have led to more stable pressure curves that provide more consistent velocities and the elongated pressure profile allows better velocities at lower pressures than previously possible.

David