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Barrel Movement- Part 3


In parts one and two, we examined barrel movement and how is effects reloading brass, as well as how to begin developing a load that takes barrel movement into consideration. If you haven’t read those two articles, it would be best to do so before reading part three.

Determining powder charge

Now that we have the reloading brass cleaned, sorted, trimmed, and primed, let’s move on to determining how much powder to start off with. Check your loading manual and determine the maximum charge suggested for your powder. Then determine how much adjustment on the powder measure will throw about 1 percent or slightly less of the weight of maximum charge of powder.

As an example, if the maximum load was 45.3 grains, you would determine the amount of adjustment of the measure that would give you about a 4/10 to 5/10 grain increment--often about 1/4 to 1/2 turn of the adjustment. Then, set your powder measure to throw a charge in the lower third of the charge weight range as recommended by your loading manual. Also note the maximum velocity indicated in your load manual so you have some idea of when you are approaching a maximum load.

Bullet Seating

Use your preferred method to set your seating die so that bullets will be seated 10 to 20 thousandths off the lands or to the workable maximum overall length if they will be used in a magazine fed firearm. It should be noted here that it may be a good idea to check your seating plug to ensure that it bears only on the ogive of the bullet and not the tip. Because bullet tips vary slightly in shape, seating a bullet by means of its tip leads to varying seating depths. It may be necessary to alter the seating plug by drilling it out slightly, so it bears only on the ogive. Some manufacturers will custom cut seating plugs for you.

Setting a seating die for the "overall length" should be done using one of the gauges that measure from the ogive and not the tip of the bullet. Sinclair and others make inexpensive gauges for this or you can fashion your own.

Time to start Shooting-Range Day

Head for the range with bag of primed cases, bullets, powder, powder measure, a single stage press, a seating die, and a "permanent" type marking pen. All you will be doing is throwing powder charges and seating bullets, so how you mount the press and measure so it is useable at the range is up to you. Some shooters just screw their stuff to a heavy wood plank. Of course, you will also be taking your chronograph, rifle rest and "sand bags," your notebook and pencil, and hearing and eye protection.

Load 5 starting rounds and slowly and carefully fire them at an aiming point through the chronograph (This is assuming you have good bench shooting technique). Record group size, the velocity and the standard deviation for the string. Increase the charge one "increment" by turning your adjusting screw on your powder measure as described above and shoot 5 more at a separate aiming point. Continue this process until you start seeing signs of high pressure or reach maximum velocity. If you get a really good group, load one sample round with that load and label it with the marking pen before adjusting the measure so you can weigh it at home later (or if you can weigh charges at the range do so and record the charge weight).

In part four of this series, we will start looking more in-depth at how to make changes to your load while at the range while taking the barrel movement into consideration.