no argument with either of your statements. Let's assume test #2 is 100% correct and just look at the slope of the averages. Can you answer these two questions? Why did the non annealed cases go through the same number of firings as the annealed cases with no split necks or other case failures noted and why did the accuracy and performance of the non annealed cases remain roughly the same from the 1st though the last firing? If case hardening is a factor in accuracy by the tenth or so firing the non annealed cases should have exhibited a noticeable deterioration in performance. Instead it was just the opposite in most tests. Dennis Dean had a increase in ES, but the vertical spread dropped by 40%, Tony Shankle - flat ES and a slight drop in group size, Ken Faulk - increase in ES, substantial decrease in vertical MOA, David White - decrease in ES and vertical MOA. With the .338 there was a increase in ES and MOA however the annealed had the same issues with the slope of the non annealed and annealed cases being parallel.
Taking a look at part II's test average trends it seems as if annealing has no effect whatsoever in vertical spread, ES, or case life. Any differences in group sizes appear to be caused by the placebo effect, a double blind test could confirm that.
Hi Jim,
Interesting observations. Like you, I would like to see some more writing on stone tablets.
Disclaimer:
I am a fully sold proponent of annealing for competition use. After much time and reflection on methodologies, I am in the process of changing from flame to induction annealing. I fully intend to do some intensive testing to satisfy my own curiosity as I have hundreds of cases around here that have been recently flame annealed.
Back to your observations:
To get 20 firings from brass of any description requires a rather mild load. In competition use, we normally beat a case to death long before that. With that in mind, I think we might see some different results based on load pressure and neck clearance. I know for a fact that my heavy FT/R loads will slowly increase velocity over the life of a case without annealing.
As for ES, I don't fully understand what methodology was used to obtain that data. I do know that a barrel will "walk" the velocity as it warms. Rate of fire and the sequence that shots are fired will induce a certain amount of noise to the data. I have to fire 2 warming shots through certain barrels to prevent this problem when chronographing.
On group size, I see two difficulties in making determinations:
First, if a rifle is properly tuned, small deviations will likely result in a small, but increasing percentage of fliers. 5 shot groups are unlikely to identify this trend. Lou's data tends to suggest this phenomenon at short range.
Second, at 1k, it is difficult to use vertical results without considering other noise in the data. That noise would include wind and its effect on vertical, shooter aim variation (the placebo effect is part of this), and barrel fouling condition/temperature.
Where I was not on-site observing the testing, I can't make any assertions about the results of the testing other than it suggests that annealing might be a good idea. In other words, it verifies that my opinion has not changed.