I got thinking about this last night after a couple pops and I figured I'd ask the more knowledgeable here. We always chase a small SD for our loads, that part makes sense. We want the most consistent load to avoid vertical dispersion at distance. However I started to wonder what truly affects, and creates a small SD. Is it the precision of loading or is it the rifle itself?
If I load 43.0 grains of H4350 in my 6.5 Creed and shoot a group of 5, with an SD of 5 that's good. However, is that because every single case is filled with exactly 43.000 gr of powder or because the rifle likes that load? What if my loads varied between 42.95 and 43.05 gr? Obviously, not as precise in the charge weight, so this could affect the velocity spread. I guess what I'm asking is, should we really be trying to find a load based on a low SD when doing an OCW test, or should we find a load based on another method, and then fine tune the SD with more precise reloading practices? Also, with this theory, it would be possible to make any load have a low SD if the precision of our loading was exact.
If I load 43.0 grains of H4350 in my 6.5 Creed and shoot a group of 5, with an SD of 5 that's good. However, is that because every single case is filled with exactly 43.000 gr of powder or because the rifle likes that load? What if my loads varied between 42.95 and 43.05 gr? Obviously, not as precise in the charge weight, so this could affect the velocity spread. I guess what I'm asking is, should we really be trying to find a load based on a low SD when doing an OCW test, or should we find a load based on another method, and then fine tune the SD with more precise reloading practices? Also, with this theory, it would be possible to make any load have a low SD if the precision of our loading was exact.