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Getting Started with Air Rifles - Part 2

00:38:48  | Join Bryan Litz as he continues exploring the flight of .22 and .30 caliber air rifle slugs and pellets using Doppler Radar at the Applied Ballistics Laboratory.  This video picks up where the last one left off, shows the systematic testing of various projectiles and compares their radar tracks when fired from different twist barrels.  Still, a lot to learn, but we start getting more useful results in this video in characterizing the flight performance of more air rifle projectiles.  Eventually, as this work matures it will be the basis for assessing and modeling Custom Drag Models (CDMs) for air rifle projectiles in the Applied Ballistics software devices.  The ultimate goal is to create ballistic models that support accurate fire solutions to many hundreds of yards!

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7 Comments

  • Ziad Abou Arraj says:

    Hello,
    concerning the low velocity first shot; the air travels from the high pressure tank (1) thru the regulator (2) to the chamber “plenum” (3) and sits there until you pull the trigger, when you pull the trigger and the hammer hits the valve, the air travels thru the valve to the transfer port up to the barrel behind the pellet(4), at the same time phases 1,2 and 3 recycle until you pull the trigger again.
    So during phases 1,2 and 3, the air fill to chamber “plenum” with the needed pressure fixed on the regulator, let’s say 150 BAR, at this exact moment the temperature of the air rises inside the chamber because of pressuring it. if you leave the rifle for some time without shooting it, the air inside the chamber loses temperature thus pressure (no more 150 BAR). so the first shot you’re gonna take will have lower pressure then it’s support to have right after phases 1,2 and 3.
    This is why during PCP competitions, we take blank shots (air only) to get consistent air pressure before shooting on the target, or even after filling the high pressure tank because the new air will have high temperature thus high pressure and we will lose consistency when temperature changes.
    Thank you for giving time for the PCP, this field is very delicate and wide and your videos are important.

    • Bryan Litz says:

      That makes sense and I’ll keep that in mind. Thank you!

      Anything else you see or would like to see covered in the testing?

      -Bryan

      • Ziad Abou Arraj says:

        Yes please, later on kindly test the same pellets/slugs with Lothar Walther and CZ barrels. It is very interesting the know the behavior of the projectiles shot thru different barrels and grooves.

        Thank you.

        • Ziad Abou Arraj says:

          As for the pellets, if you want consistency in velocity and accuracy you will have to sort the pellets per weight and head size, and the heavier the pellet, the more weight deficit you will find.

  • Adam Sisko says:

    Ziad might be right but it’s also possible you have a small leak causing the plenum pressure to be lower on the first shot. You can check that quickly with soapy water.

    I’m sure more testing is coming but the real competitors will be using pellets or slugs (not hybrid slugs). Make sure to test out Nielsen slugs and JSB pellets. This was what the original FX barrels were designed around and I think are probably the most commonly used.

    When testing slugs try to get a much faster velocity 1050+ FPS.

    Because these projectiles are so soft a lot of competitors look over each projectile for damaged skirts. These are fairly common to find and I’m sure would throw off the BC curve.

    • Bryan Litz says:

      I suspected that as well, considering it doesn’t happen to the same extent on both guns…

      Thanks for the advice on the projectiles and velocities to test. We will get there. Now is just the learning curve where I’m figuring out how to control things, change barrels, etc. Yesterday was an adventure as I installed the power kit (heavier hammer, lighter return spring, etc.) Thankfully there’s tons of online videos which are helpful. My aim isn’t to recreate those ‘how to’ videos; instead I hope to provide something that is lacking which is accurate projectile models that can be used in the AB software to support accurate long range fire solutions – THAT’S my JAM!

      -Bryan

  • Kevin Stoughton says:

    I am so glad that you’re finally doing this testing and sharing the information. I’ve been testing airgun slugs for a long time but obviously don’t have the technology you do. I’m excited to see what you come up with!

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