My error in arithmetic, I used a different number off my working papers. (Besides, I like your numbers better) No, you did not misread; I miscalculated off wrong data.
Now, on to today's results. I shot 25 rounds cast, 12rounds jacketed, then 19 rounds cast (one case was cracked in the neck, so it went into the scrap pile while prepping cases). 5 rounds cast and 2 rounds jacketed were used to adjust scope. Load was LC82 case, Lee 170 grain GC weighed out as 170, CCI 200, 22 grains IMR 4227. Note different charge. Jacketed was 165 Speer BTSP, ADI case, CCI 200, 48 grains H414. Slightly different parameters, but if jacketed before cast improves cast groups, I think it would prove so generally across the board of variables; hence, some different round preparation. Results in inches. Groups for measurement were 5 round groups except for first group after jacketed, that was only 4 rounds. Extra rounds were shot to bring groups near bullseye but not measured. Some numbers rounded.
Results: Before Jacketed After
Group : 3.30, 2.22, 3.49, 3.72 AVE 3.18 3.79, 3.35 3.28, 3.34, 3.04, 2.68 AVE 3.05
Mean Radius: 1.28, 0.79, 1.51, 1.35 AVE 1.23 1.18, 1.19 1.28, 1.07, 1.12, 0.92 AVE 1.09
Results? After the jacketed the cast did better again. Difference in group size was 3.18-3.05=0.13. .13/3.18=.041; 4%
Difference in MR was 1.23-1.09=0.14. .14/1.23=.114; 11%
Hope I got it right this time John, otherwise I may have to stay after school and clean the blackboards.
I find it interesting looking at the group size averages the mean radius averages; looking at the targets there were a couple outliers in the groups that enlarged them, and some after groups had most rounds much closer to each other than before groups. What this seems to indicate to me is that using jacketed bullets just before cast bullets helps groups. Long term, who knows, but in the short run firing 10-15 rounds jacketed before cast would help my scoring slightly. I did not get the 14% mean radius difference, but at 11% that is still significant to me. I think my new motto should be paralysis by analysis as seen in an earlier report in the forum. I do like to work numbers in spite of my arithmetic.
John, hope your trip to the range was as good as mine, especially weather wise.