.22 AEA .22, 21.9 grain ballistic coefficient

[NAProf]

@BBGunn, I don't want to come across as a dick, but pellets use GA and conventional slugs use G1, usually. I have no way of knowing who knows what, or if it was a typo, but I just thought you and anyone following might benefit knowing that. I do the same thing as you. I shoot at different distances and see what's actually happening and back calculate using Strelok Pro and I get really useful numbers to me.

Hi,
I have also heard that GA standard model is better for pellets than the G1 standard model. Maybe that is because whoever developed the standard was using pellets to come up with it.

However, I have managed to get the data points for many of the standard curves of interest to airgun shooters (from Strelok Pro) and the graph below shows all those curves in the subsonic range. Please note that for each I put a marker on the data points and then did a cubic spline curve fit to those points.

Below 1100 fps (the sub-sonic region) the GA and G1 curves are hardly different. The height doesn't really matter, it is the shape that counts. BC uses the ratio of the CD for your projectile to the CD of the standard model to essentially shift the standard model shape up. The height of the "adjusted standard" CD curve is determined by the BC value at the specified velocity and the sectional density. Air density (temperature, barometric pressure and humidity) only come into play when calculating the projectile path.

So, I don't believe it really matters which one you use. The sensitivity of you projectiles path to BC is not that great, particularily when you look at all the other variables that go into the pellet flight.

Cheers,
Greg

 

[Solo1]

This was today shooting the 50 yd comp with aea 21.9

 

[duchunter007]

This was today shooting the 50 yd comp with aea 21.9
View attachment 23048

how do you like the new chrono?

 

[Solo1]

how do you like the new chrono?

So far great! Hasn’t missed a shot, easy to read, mount on gun is nice you don’t have to worry about knocking it down. Just takes a bit to get used to how it works.

 

[LostInMO]

Looooving this thread!!

Good stuff!

Just to chime in about something I though of when reading several references about "temperature and humidity."
➧ The local air pressure is much more important than temp. and humidity when affecting your BC measurement (via velocities or drop or time of flight).
➧ And our local air pressure (not the one converted to sea level) is mostly affected by your elevation.

So, if you're making your BC measurements in the mountains, it would be helpful to
⭓ either mention your actual velocity measurements, and adding your atmospheric conditions —
⭓ or add your atmospheric conditions to your ballistic calculator.



Here's an app to calculate BC (free, by a now dead but very generous UK airgunner).
It offers you GA and other drag functions. And the option to enter the atmospheric data of your test shooting session:

EasyBC - Apps on Google Play

EasyBC is Ballistic Coefficient calculator using the ∆POI, ∆T or ∆V methods.

play.google.com

Cheers,

Matthias

Thanks Matthias, that is a really interesting app. so I've got some questions, if you please. I'm not a super-serious shooter, as far as getting into the weeds of projectiles, velocity, etc. I'm more of a 'dabbler', but I DO get super-serious about hitting my target! Especially critters. So back to the app. I like the layout! But what does it refer to when talking about near and far zeros? And I'm assuming target range is something other than where you zero your gun. But the near and far zeros confuse me. Please enlighten. Thanks.

 

[Solo1]

Near and far 0 are the 2 points where your projectile travels almost level. For my ghost 177 at 19.5 fpe it 21 and 35 yds

 

[JungleShooter]

Thanks Matthias, that is a really interesting app. so I've got some questions, if you please. I'm not a super-serious shooter, as far as getting into the weeds of projectiles, velocity, etc. I'm more of a 'dabbler', but I DO get super-serious about hitting my target! Especially critters. So back to the app. I like the layout! But what does it refer to when talking about near and far zeros? And I'm assuming target range is something other than where you zero your gun. But the near and far zeros confuse me. Please enlighten. Thanks.

What Solo1 said.

When shooter talk about their zero, they always mean the far zero.
But in reality, the proyectile exits the barrel about 2-3" below the scope.
Then it travels upward to cross the line of sight with which you've been aiming at your target = near zero.

It then travels foe 20-40y typically above the line of sight — before gravity makes it descend through the line of sight — the second crossing = the far zero.


Unless you have a very special case, in the app you select with the orange button the "far zero" and all is normal.


Matthias

 

[brantosan]

ok NICE THREAD....

Any body got any idea why this pellet is so efficient? Is it the longish skirt?

 

[Solo1]

ok NICE THREAD....

Any body got any idea why this pellet is so efficient? Is it the longish skirt?

The head diameter is larger than some? Possibility

 

[JoeWillie]

This was today shooting the 50 yd comp with aea 21.9
View attachment 23048

Yep, 950 FPS seems to be the sweet spot in several different guns with this pellet!

 

[Pumacarl]

Hi,
I have also heard that GA standard model is better for pellets than the G1 standard model. Maybe that is because whoever developed the standard was using pellets to come up with it.

However, I have managed to get the data points for many of the standard curves of interest to airgun shooters (from Strelok Pro) and the graph below shows all those curves in the subsonic range. Please note that for each I put a marker on the data points and then did a cubic spline curve fit to those points.

Below 1100 fps (the sub-sonic region) the GA and G1 curves are hardly different. The height doesn't really matter, it is the shape that counts. BC uses the ratio of the CD for your projectile to the CD of the standard model to essentially shift the standard model shape up. The height of the "adjusted standard" CD curve is determined by the BC value at the specified velocity and the sectional density. Air density (temperature, barometric pressure and humidity) only come into play when calculating the projectile path.

So, I don't believe it really matters which one you use. The sensitivity of you projectiles path to BC is not that great, particularily when you look at all the other variables that go into the pellet flight.

Cheers,
Greg

View attachment 23045

The problem, to me, with your example graph, is that the GA line (for the pellets that WE use) should never be listed as having a bc higher than .06. What is the purpose of starting a GA curve for a pellet at a spot that it's never going to be at anyway? Not that it really matters,I usually end up using observation to confirm numbers. The absurdness of the graph just kind of bothered me, especially when it says "Pellet Velocity (fps)" at the bottom. I'd like to know of a pellet that could get near a .2 bc, lol.