The basic process is pretty much the same for all my new loads:
1. Pick a bullet suitable to the purpose (big game, targets, varmints, etc.)
2. Build dummy load. I use .020“ off lands for most loads, anywhere from 0.050” to 0.150” for Barnes monos. Some of my rifles have really long throats so I just seat the bullets so the bullet base( or top of boattail) is at bottom of neck.
3. Study load data from a variety of sources, including the bullet manufacturer. I tend to use Hornady, Hodgdon and Nosler most, although Nosler max loads tend to be on the high side in my experience.
4. Pick a powder. I tend to prefer powders that are less temperature sensitive.
5. Build 2 identical strings of loads using 0.5g powder increments for rifle cartridges.
6. Fire each string at separate targets, recording velocity and POI for each shot.
7. Look for groups of 3 or more consecutive shots that group together well.
8. Pick a load in the middle of the group and build verification loads using that powder charge.
9. If verification loads shoot well, all done.
Was at the range yesterday with a SIL’s Rem 700 in 7mm RM and dev loads using 7928SSC and Barnes 145g LRX. The dev loads were, in part, based on my 7mn RM loads. Fired two strings of 6 rounds each on separate targets. Overlaying targets showed consistent POI based on powder charge, with shots 3, 4 and 5 in sub-MOA total group on both targets. Shots 5 and 6 were also sub-MOA on both targets. SIL is building verification loads using powder charge for #5. I expect they will work just fine, in shich case load development will be done after firing 12 shots.
I used to build 30-40 loads for development - 2 or 3 at the starting and low powder charges and working up to 4 and 5 for the middle charges, then tapering off to 2 or 3 at the highest charges, which were frequently a little over book max. Unfired loads, if any, would be torn apart later. I decided this method was wasteful of my time and components and tried the method above. It turned out to be simple and faster and, if things don’t work out, there are fewer loads to pull apart. Occasionally I will do a single string and have found that usually works well, especially if exploring new territory in terms of powder, cartridges, etc.
