Re: Going from 165 to 168 - drop chart help
I don't know if you have access to a long distance range, but I did the following, using the 500 meter rifle silhouette range in Tucson:
1) Recorded the load's muzzle velocity, the temperature that day and the range's elevation, while zeroing the rifle at 200 meters on paper (needed 3 rounds).
2) Used the 300 meter gong to determine and record elevation settings (dialed up 3 MOA to start, needed 3 rounds - 2 to adjust, 1 to confirm).
3)Same with the 385 meter (dialed up to 6 MOA to start, Needed 3 rounds), and 500 meter gongs (dialed up to 9 MOA to start and needed another 3 rounds).
Once I had my 200, 300, 385 and 500 meter settings, I set paper targets using the shoot-n-see type to get a view of the bullet impacts and repeated the process at 250 (started with 1 MOA), 350 (started at 4.5 MOA), 400 (started at 6 MOA) and 450 (started at 8 MOA) meters. This will be a lot easier if you have a portable gong...which I am now planning to build.
I then toyed around with JBM Ballistics (internet freebie), setting the distances in meters and at 50 meter increments from 0 to 1000, then inputed different muzzle velocities until the software produced MOA adjustments which were very close very close to what I observed the various distances I shot at.
I realized that the trajectories calculated by software differed somewhat to those determined by actual shooting, so I only use them as a reference.
I will be now be using the adjustments recommended as starting points by the software program at distances beyond 500 meters, once I have my portable gong made. I use meters because, having been shooting silhouette for so long, I am used to measuring everything in meters.
Joaquin B. in AZ
Last edited by Joaquin B; 02-16-2011 at 11:25 PM.