Pellet BC chart

[Squirrel hunter]

Does anyone have a Chart with BCs of .22 pellets.
If there is not one out there already. It would be nice to make one and put it as a sticky up top as this information is priceless
and time consuming to figure out.

I did a search but could not come up with a chart.

 

[SAZ]

I recalled seeing this info at Hard Air Magazines web site.
I'm not sure how this info ranks among all the BC info that's out there..........just trying to get you started in your search.

Ballistic Coefficients

Hard Air Magazine is publishing the World’s first comprehensive, structured and independent list of airgun pellet Ballistic Coefficients.

hardairmagazine.com

 

[SDellinger]

Look on Strelok if you have it.

 

[Squirrel hunter]

Look on Strelok if you have it.

Does strelok work on iPhone ?

 

[Enkey]

Does strelok work on iPhone ?

Hi
I saw a post that the sterlok app has been reported and cannot be installed for new users.

 

[Ballisticboy]

The problem with making a BC chart from numerous sources is that you often have no idea how the test was fired, at what speed, under what atmospheric conditions, what reference drag law was used or what method was used to calculate the BC value. All of these factors can have a big effect on the resulting BC, particularly if the wrong reference drag law is used or the wrong calculation method. It is rare for testers to measure the atmospheric conditions during the tests, so the reported figures can vary widely from each other, leading to myths regarding pellet BCs.

The HAM figures claim to have been obtained under measured conditions using consistent reference drag laws, but there have still been some question marks on their figures.

 

[JungleShooter]

Here's a chart for .22cal.
Gathered from sources all over the internet.
Where available, the footnotes indicate the specifics of the test and the BC calculation.



Do not ask how much time I spent gathering this info.
I should simply have bought two chronos and a tin of each pellet, and should have done my own testing, using a sound test protocol.
Well, I'm almost there now. This month I'll start.

Matthias


Attachment:
BC Table .22cal

View attachment PELLETS. BC Table .22cal. 1.0MB.pdf

 

[JungleShooter]

The problem with making a BC chart from numerous sources is that you often have no idea how the test was fired, at what speed, under what atmospheric conditions, what reference drag law was used or what method was used to calculate the BC value. All of these factors can have a big effect on the resulting BC, particularly if the wrong reference drag law is used or the wrong calculation method. It is rare for testers to measure the atmospheric conditions during the tests, so the reported figures can vary widely from each other, leading to myths regarding pellet BCs.

The HAM figures claim to have been obtained under measured conditions using consistent reference drag laws, but there have still been some question marks on their figures.

Miles,

When I'm ready, I'd love to run my BC test protocol by you for a quick check. There's so much to consider.....

Matthias

 

[Chuck-in-Ohio]

 

[Ballisticboy]

The JSB table has been highly criticized by many people. The G1 drag law is not suitable for any pellet design, domed, hollow point and certainly not wadcutters. No pellet looks anything remotely like the G1 projectile shape and hence multiple BC values will be required, particularly as speeds approach 900 ft/sec or much less for wadcutters. The use of the RA4 drag law for slugs is OK up to about 950 ft/sec, but again above that speed the drag laws are not the same shape.

The fact that JSB have used these reference drag laws is worrying, suggesting they know little about basic ballistic drag laws.

 

[Franklink]

In all the .177, .20 and .22 BC collections I've done, that chart from JSB is the most accurate, assuming "normal" conditions (no head or tail winds skewing data).

My method is simple, average of 10-15 shots at the muzzle and then again at 50-65yards. Then take those two speeds and plug them into something like the EasyBC app.

For smallbore pellets, it's quite surprising how little the BC changes when using GA or G1. In most instances the variance between GA or G1 is on the order of 1 thousandth, or 0.001.

Here's an example....This was with a strong tailwind and the 25.4gr .22 MRD. (The tailwind doesn't change how little difference there is between GA and G1, but does explain why the BC was so high that day. )

Both GA and G1 would round to 0.056, using typical rounding practices.

 

[Ballisticboy]

That is probably because your average velocity is only around 825 ft/sec, about Mach 0.75 and well below the drag rise Mach number for the chosen pellet with a very domed nose. Even if the BC's were identical at those speeds, it does not mean the G1 law will be accurate at higher speeds as the drag rise Mach number is reached or passed. The JSB value is for speeds around 930 ft/sec, where you would expect BC's to be lower than those measured at lower speeds due to the poor drag curve shape match, though JSB do not state what speed they are quoting i.e. muzzle velocity or average.

 

[killahog]

In all the .177, .20 and .22 BC collections I've done, that chart from JSB is the most accurate, assuming "normal" conditions (no head or tail winds skewing data).

My method is simple, average of 10-15 shots at the muzzle and then again at 50-65yards. Then take those two speeds and plug them into something like the EasyBC app.

For smallbore pellets, it's quite surprising how little the BC changes when using GA or G1. In most instances the variance between GA or G1 is on the order of 1 thousandth, or 0.001.

Here's an example....This was with a strong tailwind and the 25.4gr .22 MRD. (The tailwind doesn't change how little difference there is between GA and G1, but does explain why the BC was so high that day. )
View attachment 353116
View attachment 353118

Both GA and G1 would round to 0.056, using typical rounding practices.

Frank, I do not have the EasyBcapp and I cannot find one that is compatible with Mac systems. I am having trouble getting the Strelock program to accurately estimate the drop of the FX 22 caliber 24.4 pellet. If I sent you data collected from my Lab Radar would you load it in your app and let me know what the results are?.

 

[Franklink]

Frank, I do not have the EasyBcapp and I cannot find one that is compatible with Mac systems. I am having trouble getting the Strelock program to accurately estimate the drop of the FX 22 caliber 24.4 pellet. If I sent you data collected from my Lab Radar would you load it in your app and let me know what the results are?.

Sure, not a problem at all. Send em my way and I'll get you some screen grabs.

 

[Centercut]

Sure, not a problem at all. Send em my way and I'll get you some screen grabs.

Interesting info. Which gun were you using for the RD Monster BC calcs? Just asking because the 1.65" sight height seems very low... I agree that for most pellets, the GA and G1 profiles out to well over 100 yards produce the same flight profile. ALso, for slugs, the RA4 and G1 are very similar. I've also noticed for BT slugs like the Altaros, that using a G7 profile gives a more accurate profile out past 300 yards, but from zero to 300 it is identical to the G1 profile. I am shooting those at 890 fps, so I don't have much data from faster slug speeds...

 

[Franklink]

@Centercut and in regards to your questioning the scope height in the above example....with the speeds at two distances method the sight height isn't a factor. That option is grayed out in the app actually.

Now, if somebody was using the method of comparing impact points, than the scope height would matter. And if the one chronograph method is chosen in that EasyBC app, then the input for scope height opens up and becomes modifiable.

 

[killahog]

Sure, not a problem at all. Send em my way and I'll get you some screen grabs.

The attached string is showing the results of the FX 25.4 G starting at VO muzzle V1 distance of 1 yard V10 10 yards V20=20 V30=29 . Atmospheric conditions were 74 Deg 30" HG/51% . If necessary I could change the VO points to a longer distance but it's windy today so I would have to wait for better conditions . Thank you

Shot ID;V0;V1;V10;V20;V25;V29;Ke0;Ke1;Ke10;Ke20;Ke25;Ke29;PF1;Proj. Weight;Date;Time

0014;944;942;918;893;881;869;50;50;48;45;44;43;24.21;25.70;05-23-2023;19:42:30;

0015;941;938;915;891;878;866;50;50;47;45;43;42;24.11;25.70;05-23-2023;19:42:44;

0016;941;939;916;892;879;867;50;50;47;45;44;42;24.13;25.70;05-23-2023;19:42:50;

0017;940;937;915;890;879;869;50;50;47;45;44;43;24.08;25.70;05-23-2023;19:42:58;

 

[Franklink]

Gotta love the confusing way Labradar displays data.....

Okay, if I'm interpreting correctly, you've got data for 4 shots. I prefer to have 10-15 shots b/c that statistically reduces the effect any one outlier can have on the results, but 4 shots is better than one shot. And your extreme spreads across all four shots at each of the distances are pretty good, so the data were feeding it isn't too bad. I'd like to see an average speed for further downrange (50+ yards) but as you stated, wind is messing with you today.

I worked it up for 29 and 30 yards, due to how you worded your explanation.

J11 is the average of the BCs from 20, 25, 29, and 30 yards. Theoretically BCs change with distances so averaging them this way isn't ideal....Experts like Miles teach that if the reference drag law was perfect, the BC would be the same at all distances.

And the screengrabs...

 

[killahog]

Frank, Thank you for taking the time to input and interpret the data. I certainly have more shots that. I can include however I only set the distances as. far as 29 because at the time the muzzle velocity was the only thing I was interested in. The next time I shoot I will set the VO for out to 80 yards or farther. Now I need to try and figure out why I have to manually adjust the BC in Strelok to 0.075 (G1) in order to get anything close to an accurate estimate .