With regards to throwing case charges vs. weighing each load;
About 15 years ago I came to a conclusion (however false this conclusion might have been) that some of the so-called extremely accurate factory ammunition that many of the rifle-smiths of the day were using to prove they had “accurized” your rifle, were actually weighed on the assembly line and not thrown from a powder measure. Considering the very real issue of varying case weights coming down the assembly line, the heavier (thicker) have less volume inside, thus producing more pressure compared to a lighter case with more powder.
I decided to do an experiment with military brass that I had formed from Mil-Spec 30-06 brass. The brass was from different lots and varied considerably in weight but were all fire-formed in the same chamber and trimmed. I will have to dig through my notes to find what chambering I conducted the test in since I have formed 8X57, 7X57 and 308 all from the same Mil-Spec brass.
But what I essentially did was take 20 cases and weighed them all and marked the weights on the side of each case. I then took the three lightest cases and worked up what I considered a safe working load with that particular powder & bullet combo. So let’s say the safe load was 50 grains of powder X in a case that weighed 180 grains. I then filled the three lightest case along with the 50 grains of powder X charge inside and recorded the total weight of case and powder. The result would be a case weighing 230 grains. I then took the remaining heavier cases and filled each case with the same powder to equal the same total weight of the lighter cases, i.e. 230 grains.
In other words I had 20 cases all weighing exactly 230 grains with powder inside. Now remember the cases themselves varied as much as 3-1/2 grains or more, so the end result was the heaviest cases had 3-1/2 grains or so less powder inside them. I then seated the bullets to the same depth and fired them at a 100 yard target over a chronograph.
This very “limited” experiment produced some surprising results. As I recall the velocities did vary more than most shooters would like but the loadings produced pretty decent accuracy, roughly about a 1-1/2” to 2’” groups at 100 yards.
