0.22 LR Ballistics Question

[Okrang]

Morning all,

I recently contacted Eley to ask them what the official Ballistic Coefficient number is for their Eley Subsonic Hollow 38 grain ammunition.

The reply I received contained the following information: 

"I can confirm the ballistic coefficient for all our products is the following:

0.140 - G1 Drag Table

0.112 - RA4 Drag Table

I hope this information helps with your investigation."

I am relatively new to the mysterious world of bullet ballistics and am in the process of setting up the Ballistic Calculator on my new scope, based on using Eley Subsonic Hollow 38 grain ammunition.

Can someone kindly explain in layman's terms, the difference between the 'G1 Drag Table' and the 'RA4 Drag Table' and which coefficient number I should input into my Ballistic Calculator?

I remain grateful in anticipation,

John.  

[scarecrow243]

Hi use G1   .22 lr subsonic  remington 38grn  b.c.  0.125   CCI  40grn  subsonic b.c. 120  hope this helps

[Okrang]

Thanks for that Scarecrow!

Any idea what the different Drag Tables refer to though?

Cheers,

John. 

[Rewulf]

44 minutes ago, Okrang said:

Any idea what the different Drag Tables refer to though?

Id try a google search if you want to explore the rabbit warren of BC s.

Calculating BCs is a very inexact science, most calculators like Strelok or Weta allow you to adjust to your barrel/velocity, as different muzzle velocity/twist ect affects the BC .

Not to mention the bullet manufacturers often rather fanciful marketing figures (Higher BC = more accurate bullet, less drag = more speed / energy)

Most serious target shooters will tell you that true  BC is something you work out yourself.

[Okrang]

Thanks Rewulf.

I spent a fair while on Google this morning and found, not only did explanations seem to contradict each other, but also the knowledge was so riddled with other abbreviations and technical terminology beyond my ken, that I gave up! I figured I would come here for a more simple explanation.

It seems rather as though the world of ballistics is a bit akin to that of astrophysics - if you aren't already an astrophysicist, you wont understand the principles!

Cheers,

John.

[Rewulf]

22 minutes ago, Okrang said:

and found, not only did explanations seem to contradict each other

Thats why its a rabbit warren, and a pretty pointless one , unless youre looking at achieving that perfect one mile group !

When it comes to .22lr ballistics , its more about consistency with ammunition, and finding the bullet that suits your barrel.
Dont expect too much, and you wont be disappointed 😄

[wymberley]

45 minutes ago, Rewulf said:

Thats why its a rabbit warren, and a pretty pointless one , unless youre looking at achieving that perfect one mile group !

When it comes to .22lr ballistics , its more about consistency with ammunition, and finding the bullet that suits your barrel.
Dont expect too much, and you wont be disappointed 😄

^^^^^ This.

But for a working 40 gr subsonic round a BC of 0.125 will give a reasonable idea as a starter for ten. Below 1400 ft/sec with 22LR, RA4 is the same as G1.

[Ultrastu]

So I just put those 2 bc values into chairgun for a 40 grn sub sonic .22 lr at 1050 fps  and compared them side by side . The difference was 2 fps at 100 yds  and absolutely  no difference in trajectory  or energy retention. 

Suffice to say there is no difference between the 2 bcs under there respective drag laws  .

Just pick one and stick with it .

 

[Ultrastu]

Equally  if you compare both those bc values in just one of the drag laws. You get a 25 fps difference  at 100 yds (which you would expect. )  

But I promise you  there isn't a man alive who can shoot the difference between 25 fps at 100 yds  .There are just far too many other variables  at play masking that 25 fps . 

[Okrang]

Thanks ever so much guys - this gives me the confidence to set 0.125 as my BC.

It's all a bit of a foreign language to me, but I take your point about there being very little real difference between the two values, when all other variables are taken into account and I'm certainly no top marksman.

Thanks again for taking time to reply and explain.

Cheers,

John. 

[Newbie to this]

2 hours ago, Okrang said:

Thanks ever so much guys - this gives me the confidence to set 0.125 as my BC.

It's all a bit of a foreign language to me, but I take your point about there being very little real difference between the two values, when all other variables are taken into account and I'm certainly no top marksman.

Thanks again for taking time to reply and explain.

Cheers,

John. 

Strelok has Eley 38grn hollow points as 0.139.

[Walker570]

8 hours ago, Rewulf said:

Thats why its a rabbit warren, and a pretty pointless one , unless youre looking at achieving that perfect one mile group !

When it comes to .22lr ballistics , its more about consistency with ammunition, and finding the bullet that suits your barrel.
Dont expect too much, and you wont be disappointed 😄

100%  Find a cartridge which suits and then stick to it BUT also do not mix boxes unless you check the production codes on the boxes.

[Okrang]

1 hour ago, Newbie to this said:

Strelok has Eley 38grn hollow points as 0.139.

AAaargh....... don't do this to me!

Just when I thought I was there, the goalposts have moved!

Does this mean the 0.140 G1 Drag Table figure from Eley is my best choice?

Cheers,

John.

[Newbie to this]

1 minute ago, Okrang said:

AAaargh....... don't do this to me!

Just when I thought I was there, the goalposts have moved!

Does this mean the 0.140 G1 Drag Table figure from Eley is my best choice?

Cheers,

John.

No idea 🤷‍♂️

[Rewulf]

23 minutes ago, Okrang said:

Does this mean the 0.140 G1 Drag Table figure from Eley is my best choice

Like Ultrastu has said, at normal. 22lr ranges, it makes zero difference. 

[Ultrastu]

What you have to understand  about the  bc .value you put in .is that it's just an average  . The shots you fire some will fly all the way to the target with a higher bc .and the next shot possibly a much lower than your average .

A bullet that comes out the barrel stable may after 25 yds start to wobble and the bc value tumbles .

The next bullet stays very stable and true all the way to the target .giving a very high bc .there are loads of reasons why this may happen  not least the weather the bullet is flying through on that particular  shot . Wind, rain .fog  sun . cold , heat  etc   .

Also another thing .your bullet velocities  exiting the barrel can / will vary  up to 100 fps   depending on quality of manufacture.  This will  make a monkey  of your bc values  .

[wymberley]

The most consistent round (and therefore best in my rifle) I ever used were the SK which they now no longer do in HP. For their trajectory from my gun their BC equated to 0.136. Using the same criteria except for the BC which I've changed to 0.125 and for comparison we get a bullet path in inches of:-

Range (yards)  25      50      75      100

BC 0.125         0.98   1.39  - 0.60  -5.13

BC 0.136         0.97   1.37  -0.59  -5.06

BC 0.140         0.96   1.36  -0.58  -5.03

Some time back Ruger produced a table of ballistic criteria for various rounds. I picked on the Eley Subsonic Xtra Plus HP 22LR 40gr as an average run of the mill offering, the figures for which equated to the 0.125 BC. Have tossed in the BC 0.140 for the sake of it.

For all practical purposes, are you going to be able to tell the difference?    

[Okrang]

Ah, ha ........now I'm getting my brain around it!

Sorry I've been slow on the uptake and thank you all for your patience.

I was treating the BC figure like some kind of crucial holy grail and didn't realise how little difference second decimal point variations would make over .22 LR viable range.

Thank you!

Cheers,

John.

[wymberley]

Finally, there’s RA4:

 

This model is designed for heeled bullets commonly used in rimfire rounds like the .22 Long Rifle. It is rarely used.