ridgerunner,
There are many different ways to test for accuracy from sand-bag testing to Ransom rests to the more exotice fixtures to hold a firearm to test for accuracy. All forms should include a base-line test with factory ammo.
I normally choose to use the ammo from the manufacturer that I will be using in my reloads. Winchester ammo or Remington (for my personal loads) fired from a rest on a bench in four, five round groups being sure to let the barrel cool between each shot and cleaning after the twenty shots. I fire twenty shots the same way over a chronograph - I can't shoot accurately and worry about the sky screens at the same time - to find the average velocity the standard deviation and extreme velocity spread. I record all the information and keep the test target for reference.
I look for the powders that are recommended for my cartridge and bullet weight that offer the highest velocity - selecting at least three to begin with.
I do some research to find loads that lie within the starting and maximum loads that tend to offer the best accuracy (asking the folks here is always a big help). I then load five of each powder with the same primers and bullets in increments of .2 grains one grain above and one grain below the suggested loads. I fire for accuracy using an identical system as with the factory loads. I record the groups by using the targets as records and place them with the load's data. I usually end up with at least two loadings that show the smallest groups. I take those and put new loads using .1 grain increments to cover the powder charges above and below the first loads. When I get the best groups of my loads I fire twenty over the chronograph and four, five shot groups with the two or three best combinations. The chronograph will give me the average velocity, standard deviation and extreme spread of the three loads. The most accurate load does not always have the "best" numbers but I try to choose one that has the best results in both worlds. I then shoot the round I choose a few times at the range - different days and weather conditions to make sure it is a consistant load. Then, when I am satisfied with the load I shoot another twenty (four, five shot groups) at a target for accuracy and save it for my permanent records along with the complete load data.
Mine is not the quickest way but it does produce good groups and ammo that can be trusted under a wide range of conditions. It also allows you to shoot your weapon enough to become comfortable with it. You end up with a load and gun in which you have a degree of confidence.
PaulS
