Ballistic Theory Changing My Thinking About Slugs

Ima take a semi-wild stab at this and guess the .284/7mm. Well known ballistic advantages.

The 5.9" would be an extremely fast twist rate for such a light (but subsonic) projectile.
 
As to the question posed, the .183 cal should have the advantage in BC.... It should have the lowest Form Drag, and since they all have the same SD, a higher BC, as BC = SD / FF....

Bob
Your work is greatly appreciated! Would you think that focusing on development of higher weight better .177 cal slugs and associated higher power air rifles would be a useful goal for companies already producing that caliber? Air Hunter Gerhard from South Africa demonstrated a 400 yd shot with a .177 cal quite a while ago. It took 8 shots to hit a can of soda. The only caveat is how much FPE is worth developing. A .177 cal 100gr slug propelled at 10K fps would need some materials science applied for sure! 😂
 
Not to mention some super-duper powder, lots of it, and a really, really long barrel.... That is 22,000 FPE!.... The required twist rate would be about 2.5", and the slug about 1.9" long!....

Bob
 
For PCP air gunners, a more suitable approach might involve using the GA model or even custom drag models tailored to the specific shapes of air gun projectiles. Here are a few steps to consider:

  1. GA Model: The GA model is designed for projectiles with shapes more similar to air gun slugs. It can provide more accurate BC values for these types of projectiles.
  2. Custom Drag Models: Some advanced ballistic calculators allow you to input custom drag models. These models can be created based on empirical data from shooting tests, providing a more accurate representation of how your specific slug behaves in flight.
  3. Empirical Testing: Conducting your own testing with a chronograph and target at various distances can help you determine the actual performance of your slugs. By measuring the velocity drop over distance, you can calculate a more accurate BC for your specific setup.
  4. Software Tools: Use ballistic software that supports custom drag models and allows you to input your own data. Tools like ChairGun or Strelok Pro can be very helpful for this purpose.
By using these methods, you can achieve a more accurate understanding of your PCP air gun’s performance and optimize your shooting experience.
 
For PCP air gunners, a more suitable approach might involve using the GA model or even custom drag models tailored to the specific shapes of air gun projectiles. Here are a few steps to consider:

  1. GA Model: The GA model is designed for projectiles with shapes more similar to air gun slugs. It can provide more accurate BC values for these types of projectiles.
  2. Custom Drag Models: Some advanced ballistic calculators allow you to input custom drag models. These models can be created based on empirical data from shooting tests, providing a more accurate representation of how your specific slug behaves in flight.
  3. Empirical Testing: Conducting your own testing with a chronograph and target at various distances can help you determine the actual performance of your slugs. By measuring the velocity drop over distance, you can calculate a more accurate BC for your specific setup.
  4. Software Tools: Use ballistic software that supports custom drag models and allows you to input your own data. Tools like ChairGun or Strelok Pro can be very helpful for this purpose.
By using these methods, you can achieve a more accurate understanding of your PCP air gun’s performance and optimize your shooting experience.
GA is specifically for round head airgun pellets. For slugs, you should use RA4 or SLG0.
 

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