1 - How much variance in powder charge is allowed on factory ammunition? Lets use .30-06 Remington core lokts as the example.
2 - How uniform or how much variance do you get using a powder measure? Lets use a nice ball type powder such as H335 and compare it to something like Varget - also if you could name the powder measurer that you use it would be appreciated.
3 - How much variance do you accept in your powder charge?
Currently I'm weighing every charge and their within .1 grains of each other but its very time consuming....
1) As has been pointed out, factory loads use bulk powders which are blended to a specific pressure and velocity range for the intended loads to be made. They have to be able to be loaded in several different types of firearms, so the pressure curve will be sufficient to operate gas, function in pumps with out locking them up and also be accurate in bolt actions. Their loads might vary up to .5grs but the pressures and velocity will still be fairly consistent.
2) I use Uniflow measure for about 98% of my loads. I have one set up with the small rotor and dedicated to handgun loads, and two others for rifle loads. The handgun charges I have found generally run .02grs more or less depending on which powders I am shooting. With something like Unique which are flake, is where the variance is more notable, where as powders like 2400 or 296 flow just about on the money every throw. The issue with rifle loads and the stick powders is that sometimes you get grain cutting which will tend to vary the weight a tad as well as depending on the length of the stick, you will get differing compressions of the powder in the bore of the rotor. This however will generally still get you to within .02gr or so which in most mid sized cartridges will not change a lot in the way of performance out to around 300yds. In smaller cases like the 223, you will see a wider variance in performance due to the smaller case capacities. For those smaller cases I do weigh out stick type powders, but if using ball powders they are generally close enough with the scale when simply thrown.
3) The loads specific purpose dictates the variance. Some loads I weigh out simply due to them being used for exacting accuracy, some that are used for general target practice, or general hunting, are simply thrown and the bullet seated. These are mostly mid range loads, and the accuracy of them runs around 1" or so on average. Plenty good for everything I shoot, at or under 200yds. For the longer range loads, depending on the powder, I throw some of them and weigh some of them. Depends on whether loading stick or ball as mentioned above.
I use my Uniflows for load development as well, weighing out selected powder charges and recording the min and max setting on the stem. Then once at the range, I start at the minimum setting and work up in 1/4 turns or less depending on the load, until I hit something that has promise. At this point I will weight out several charges on either side of the setting, and verify the best load for that particular combination. Then once finalized I will record the setting for that load on my stem for future reference. Depending on the powder type future loads will either be simply thrown after verifying the setting or thrown and trickled up to the proper weight.
I learned to load using a scale, but at that time I only loaded up around 50 rounds at a time. Now I load anywhere between 50 and 500 rounds, and sometimes more, at a time so the measures are really the only way to go in some cases. What ever deminished accuracy that the deviation might have, is generally not as critical as me doing my part in putting the bullet where it needs to be.
