I just wanted to relate something that i have discovered with commercial ammunition and my XD9 tactical. I purchased it new and when i got it found out it was shooting low and to the left one foot at 25 yds. It was not just me shooting it my son-in-law, who shoots at 45 had the same problem. Turns out my sites needed to be adjusted and the barrel recrowned (but thats another story). It shot alot better but still would send rounds low and to the left. I looked on the "net" for information and found OAL (Over all length) or COL (Cartridge overall length) of the rounds has a substantial effect in some guns. I had recently purchased 1000 rnds of 9 mm Winchester 115 grain FMJ online so i decided to measure some of bullets to see what was what. The results surprized me. see below
I took 5 of each (except the longest as there were only 3+1 at 1.166) and shot targets at 10 m bench rest with my XD9. The results are below.
I measured 457 rounds with a Frankford Arsenal digital micrometer.
COL Numbers Group size
1.156 13 7.5
1.157 20 4.75
1.158 59 4.875
1.159 54 4.5
1.160 83 4.25
1.161 104 4
1.162 78 2.25
1.163 32 3.25
1.164 10 3
1.165 3 2.25
1.166 1
The results showed me that my gun does not like the shorter rounds eg. 1.156 in ones (of which there were 2.8%). It also showed me that commercial ammunition was not as good as i expected it to be. I recently purchased a Dillon 550 reloader and am now reloading with Hornady 121 gr HAPs. I still have to do the experiment where i test for optimal length for this bullet but im having too much fun shooting IPSC and IDPA. Just thought i should share this info with others.
I took 5 of each (except the longest as there were only 3+1 at 1.166) and shot targets at 10 m bench rest with my XD9. The results are below.
I measured 457 rounds with a Frankford Arsenal digital micrometer.
COL Numbers Group size
1.156 13 7.5
1.157 20 4.75
1.158 59 4.875
1.159 54 4.5
1.160 83 4.25
1.161 104 4
1.162 78 2.25
1.163 32 3.25
1.164 10 3
1.165 3 2.25
1.166 1
The results showed me that my gun does not like the shorter rounds eg. 1.156 in ones (of which there were 2.8%). It also showed me that commercial ammunition was not as good as i expected it to be. I recently purchased a Dillon 550 reloader and am now reloading with Hornady 121 gr HAPs. I still have to do the experiment where i test for optimal length for this bullet but im having too much fun shooting IPSC and IDPA. Just thought i should share this info with others.
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