How to Reload Hunting Ammunition
The OCL has a big influence on the accuracy of your loading. Even small variations in the seating depth of the projectile can cause a significant variation in group size.
Once again, my comments are for hunting loads, not benchrest or target shooting.
Having determined the JTL (the seating depth that results in the projectile just touching the rifling lands on chambering the loaded cartridge) we are ready to load some test ammunition, as follows.
Firstly, hand-loading your own ammunition is fun and can produce the most accurate rounds with your choice of bullet. However, it is potentially very dangerous as well. You need to be focussed and methodical in what you do. Reloading is not a social event; it is best done quietly and alone, without distractions.
Look up the recommended loading data for the projectile and propellant you are using. It is wise to look up at least two different sources of data in order to confirm the information.
Never start with a maximum propellant loading, no matter what your best buddy might tell you, or whatever confidence you have in yourself. Start at least one or two grains less in the smaller calibres and a little more in the big bores.
Take notes of what you have chosen to load. Months later you may well have forgotten, or worse, have incorrect recollections.
Gather your cases. Inspect them closely to ensure they are clean and free of any blemishes or faults. Either test your empty cases to ensure they all chamber and eject smoothly, or simply resize them. For big or dangerous game hunting it pays to full length resize your cases prior to loading.
Prime your cases. Most reloading presses have a primer seating facility. However, it is more convenient and of superior repeatability to use a special primer seating tool.
In our test batch of ammunition we are only going to vary the OCL. We are using the same cases, the same primers and the same propellant loading.
Batch A – set the bullet seating die so that it produces an OCL that is about 5 to 10 thousandths of an inch less than the JTL. That is, your seated bullet will be 0.005 to 0.010 inch short of touching the rifling lands.
Measure out your weight of propellant and charge each empty, primed shell. Take your time, work to a set routine and develop the habit of double checking your powder charging. I have a number of cross checks, ending with a visual inspection of each case with flashlight before I seat the bullets.
Place your charged case in the shell holder, position a bullet over the case and seat the bullet with your press. Take the loaded cartridge out of the press and place it in the loading tray. In doing that I have developed the habit of shaking the cartridge up close to my ear. I expect to hear the same sound of the powder being shaken within the case, or no sound if it is a compressed load. It is a final check on the correct amount of propellant being in the loaded cartridge.
Load 7 cartridges. Take your callipers and check the OCL of the batch.
Take a slip of paper and write on it the details of the load you have just done – projectile type and weight, OCL, cases type, propellant charge and primer. Place that slip of paper in a zip-seal sandwich bag along with the 7 loaded rounds and seal the bag.
You can now repeat that exercise for Batch B, which will be 5 rounds with an OCL that is about 10 thou shorter than that used in Batch A.
I generally do 3 more batches of five rounds each. Each batch is in its own zip lock bag with a piece of paper detailing the particular loading.
Assuming that the rifle barrel is shot-in and clean, I fire two rounds of Batch A to settle the barrel, and then go about shooting a group on a clean target with the remaining 5 rounds of Batch A. Check for signs of pressure then place the fired shells back in the bag with the info slip for future reference.
Find something else to do for 10 or 15 minutes (you have other rifles – right?) and let the barrel cool down again.
Pick another clean target and fire off the next batch of 5 rounds. Keep track of which batch was shot on which target.
Your next batch of loads will be based on that OCL which gave the best group. Load another 5 rounds to the same OCL as that load. Then load two more 5 shot batches. One batch with an OCL 5 thou less, the other batch 5 thou more than the best OCL group. Test these at the range. Repeat OCL variations as required until you have the best grouping OCL. Then start to increase and test the propellant charge.
Increase the propellant charge by 0.5 grain and test 5 round batches at the range. Keep a close watch for any signs of excessive pressure and back off if found. Regardless, do not load in excess of the recommended maximum propellant charge.
Once you have the powder charge determined you can load as required for hunting.