Most guns shoot well around 575 feet per second, but check your manufacturers manual for the specifi cation of the gun. Many guns test well up to 600 feet per second.
Middle Weights, then switch to another manufacturer, rather than toggling be- tween brands and weights. It is very common to have to shoot 5-8 shots between manufacturers as these guns detect the slightest changes. Develop the habit of doing this every time you switch either the weight of the pellet or the manufac- turer of the pellet. Develop a pellet testing
sheet that records the pel- let manufacturer, lot num- ber, grain weight of the pel- let, group diameter, velocity range, standard deviation and average velocity, as well as a note section to jot down how the group behaved. For instance, if the group shot a 5.6 mm group (world-class group) until the ninth shot and then had one pellet that tossed the group to a 6.4, this group deserves a re- test. The notes section can help you remember instanc- es like this.
Other things to note:
• Be sure to fi ll your air cylinder every 90 shots - you’ll be surprised how many pellets a pellet test can require.
• Keep accurate records and notes.
• Test as if you were shooting; rhythm can make some difference, but generally not more than 1/10th of a milli- meter. Don’t shoot one ten shot group in 40 seconds and then an- other in 5 minutes, for instance.
Send lead down range! Once you charge the gun
with air, it is prudent to shoot three to fi ve shots. Next, re- start the test so that you can verify that the gun is fi ring properly and that the test setup is not moving, then shoot a 10-shot group. Use your pellet record sheet and record all of the items listed above. If the group diameter is less than 7.0 mm, the
56 USA Shooting News | July 2015
group should be retested. When deciding on a group, you should have at least three, 10-shot groups with data for each group. The most diligent students will shoot half of a 500 count tin before deciding on a pellet. The more precise you want to be, the more sample sizes you’ll need. A large number of samples will provide both the confi dence in your test results, as well as enough data to make a highly-in- formed decision.
What are ideal numbers? You might be asking your-
self: How much do standard deviation and velocity chang- es matter? The fi nal test to see how accurate a pellet is matched to a gun is always the group size; however, most guns that shoot world- class groups will maintain a very consistent velocity with a low range and with a low standard deviation. For nine out of 10 guns, this is true, but there are some guns that
shoot highly accurate groups and have no statistical cor- relation to velocity, but 90% of the times, these common velocity traits exist. Keep in mind that the end test and determining factor is the group sizes and group be- havior. More information on group diameters has been outlined in the May 2015 ar- ticle. As a reminder, groups under 5.8 mm are fantastic and groups of 6.0-6.1 mm are highly acceptable.
• Velocity range should not be over 15 fps per 10 shots
• Standard deviation should be under 4.0, under 3.0 is ideal and under 2.5 is fantastic for 10 shots.
• The average velocity will vary by up to 25 feet per second just by switching pellet weights and man- ufactures.
• Ideal group diameters are 6.0 mm, 5.8 mm groups and under are fantastic.
• Velocity should be ap- proximately 575 feet per second, but each manu- facturer has a slight ly- different specifi cation. Many guns test up to 25 feet per second higher.
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