I noticed something yesterday and I don't know if this is real or an artifact of the Shot Marker electronic target system. When I tested my .308 loads through my CED M2 chronograph, I got a SD of 9.2 at the muzzle. At 600 yards yesterday the Shot Marker electronic target system gave SDs for 20+ round strings of 12.7, 17.1 & 18.6.
This got me thinking about the possible causes for the different SDs:
1. Since they were separate sample sets, loaded on different days and shot under different conditions, the SDs were actually different.
2. The Shot Marker system isn't really accurate for measuring SD and those numbers should only be used for entertainment value.
3. There are really things that happen between the muzzle and the target that act to increase the SD of rounds at 600 yards.
I was just wondering if anyone had studied this subject, for instance, by comparing statistics of bullets as they leave the muzzle and as they enter the target? Has anyone compared the velocity statistics provided by an electronic target system with those provided by a chronograph at the target? Just thinking out loud.
This got me thinking about the possible causes for the different SDs:
1. Since they were separate sample sets, loaded on different days and shot under different conditions, the SDs were actually different.
2. The Shot Marker system isn't really accurate for measuring SD and those numbers should only be used for entertainment value.
3. There are really things that happen between the muzzle and the target that act to increase the SD of rounds at 600 yards.
I was just wondering if anyone had studied this subject, for instance, by comparing statistics of bullets as they leave the muzzle and as they enter the target? Has anyone compared the velocity statistics provided by an electronic target system with those provided by a chronograph at the target? Just thinking out loud.