GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: SciGuy on December 17, 2012, 02:06:07 PM
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I recent post I discussed some grouping I did to see if recent changes to my setup had changed my guns pellet preference. Results from that testing showed that JSB Exact Heavy was still the preferred pellet.
Since my spiral down the Benchrest obsession is still intact I spent much of Saturday shooting groups with chrony readings for every shot and notes on shot location. I shot 13 10-shot groups at 25 meters. I did not adjust for wind (same poa for all shots of a group). Wind for the duration of the session was 3-7 MPH right to left. Using Chairgun the expected group size for a 4 MPH wind spread comes in at .48 inches. The mean group size using the 12 groups where the gun was on reg came in at .598 worst outside edge (.118 greater than that calculated by CG). All worst edges ended up being on the horizontal and were likely wind related. Group #6 was opened up by 2 fliers that occurred during gusts that were in the 10 mph range. If I exclude that group from the mean group calculation I end up with a .577 mean (.097 greater than CG calculated).
Here are the numbers:
#----Group size-Low ----High -----Avg ---Sprd ------SD
1 .459 865 886 870 21 5.7
2 .684 867 876 870 9 3
3 .531 868 873 870 6 1.7
4 .695 858 869 867 12 4
5 .688 859 871 867 12 3.2
6 .816 862 872 868 10 3.7
7 .441 863 871 867 8 3.2
8 .692 835 871 853 36 12.4 (came of reg shot 5 of group)
9 .601 864 875 868 11 3.3
10 .621 864 874 869 10 3.3
11 .525 866 872 869 6 2.2
12 .488 866 874 869 8 2.6
13 .623 866 872 869 6 1.7
So what do I think all this tells me.
1: I get 70 good shots before coming off reg (already knew this)
2: I can probably put the chrony away for awhile
3: My current pellet cleaning/sorting/lubing procedure seems to be working OK
4: CG wind drift calculations seems to be pretty accurate
5: In calm conditions I should be able to shoot sub .25 worst outside edge groups
6: If #5 if true, this gun is capable of shooting a 250 on the WRABF 25M target
7: At 25 meters the velocity spread/StDev in my groups does NOT correlate with group size