redneck2 said:
has pretty much indicated that Water's case head expansion is questionable at best. When he did those tests, inexpensive and accurate pressure testing equipment and chronos were not available. He did the best he could with what he had.
Waters stated that his case expansion measurements give relative indications, and indeed that's what they are. He never claimed that .xxxx measured = xx,xxx psi in a given caliber.
In your basic bolt action rifle or Ruger single action, the gun is much stronger than the case. If one is satisfied with the factory load performance, shoot some of them, and check the pressure ring on the fired case. When your loads match them, you should be getting velocities reasonably close, as well. This method does assume that you're using a reasonable powder choice - as you said, trying to get max velocities with Bullseye in a .45-70 is one silly example of doing it wrong - the pressure will hit max long before you match factory load performance.
Assuming that I am using a strong action, and proper powders, I will load up until I either see inaccuracy, or I begin to see the start of solid web expansion in the case head. THAT is time to back off, regardless of how brave you are, how strong the gun is, what the chrono or the load manual tells you.
Expansion varies considerably with chamber sizes, brand and quality of brass. Testing with some of his loads showed them to be significantly above acceptable pressure limits.
Again, he used expansion for relative measurement. If you fire factory ammo, then reload the same cases in the same gun, you're getting a good relative pressure reading.
The notions of "acceptable" pressure have varied a lot in the last 30 years. What was a fine load for a lot of guns has indeed dropped over the years. Part of that has been discussed in some of the better handloading magazines. Modern ballisticians do statistical analysis on loads, to assure that none of a batch is statistically predicted to exceed SAAMI pressures. In many case they have found that the average load must be reduced to assure that safety requirement( i.e. lawyer - proofing) is met. It is also true that brass has gotten thicker than it was 30 ywears ago. There is no way I would accept a load from 30 years ago and try it without working up carefully. I personally haven't tried the home pressure testing equipment. I probably should, it might be amusing.
Judgement is of course required when you are loading for a gun of lesser strength, or trying to load to a particular power level. A chrono, and case expansion are all good tools. Chronos are just plain fun, anyway, and you might just find a batch of factory ammo that doesn't meet expectations. I once had a box of factory .25-06 that clocked 300 fps less than claimed!
