Tuesday, July 20, 2010

A lesson from the Boot Camp

Hello again,
We were thankful to be able to come home for a shower and to do the chores in between each day of shooting. We left in the morning right after I milked and we got to the range about 8:30. Mom strained the milk for me and did the milk dishes for the morning milking. Thank you everybody for keeping things running after we were gone!

One of the most important things that I learned was how to apply the bullet trajectory to long distance shooting. Every bullet drops as it goes out the barrel and it drops more as it goes to farther distances. So even if you fire a good shot, you are going to miss the target unless you adjust your sights to compensate for the bullet drop. After I understood what I was doing, it was an easy matter to figure out the drop of the bullet for my caliber.

I'll quickly explain how to chart the drop of a bullet as it leaves the barrel so you can do it on your own. Zero your rifle at 25 meters and make sure you can get all your shots in about a 1 inch square. If you try to collect information from a random group, then you will get incorrect data and plot your bullet drop wrong.

Then move out to 100 yards and fire 5 rounds from prone at the center of the target. Check your target and measure the distance that the center of the five-shot group is from the target. Write it down! But don't adjust your sights. Make sure you convert all the inch measurements into Minute Of Angle measurements before you write it down. Otherwise your numbers will confuse you like they did me. (if you don't know what a MOA is, go to an Appleseed shoot!)

Then go out to 200 yards and collect the same data as you did at a hundred yards. The groups might be high or low, depending on what type of cartridge you are firing but don't make any adjustments on your sights. At the RBC we were shooting at 20" wide silhouette targets that had a backer that was about five feet square so it caught any stray shots or groups that ended up being low or high.

Then move out to 300 and 400 and as far out as you have room to shoot. You should be able to draw out a chart like this that shows how the bullet drops. Each of the verticle dashed lines is 100, 200, 300, 400 yard marks. The little squares represent each MOA up or down that the bullet traveled at each distance. As you see, at 100 yards the bullet hit 3 MOA high, then at 200 it was 1 MOA lower than before, at 300 it was right on and 400 it was 1.5 MOA low. With those measurements I can adjust my sights from where it was sighted in at 25 yards, up 1.5 MOA and make a hit at 400 yards without firing a shot! If I didn't adjust I would hit 6 inches low with this caliber.

We were told that we need to make up a bullet drop chart for each different ammunition that we own, and for each different rifle, and store the charts with the ammo so you always know the sight adjustments for it.

I have more to tell, so stay tuned for the next post!


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