SLG1 is for boattail slugs, SLG0 is for large meplat slugs with cylindrical bodies. Many long distance slug firers have found RA4 gives good agreement with their firing data, but it may be MV dependent to some extent.
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Manufacturer listed ballistic coefficient
- Thread starter air-hunter_canyon
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ZAN 44 gn is hollow point boattail and 46 gn is ball head boattail, I have couple boxes of these. I was saving these for next season, hoping so to have access to 200 and longer ranges.
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RA4 is supposed to be a good match for 22 rimfire. As far as I know, it’s debugged well enough. I use RA4 with 106gr 7mm BT airgun slugs at 1050fps and it’s a significantly better match than the G1. G1 does not do so well when I get into the 950-1050fps range
I have not used SLG1 but I have seen some drag curves and it looks like it would also be better than old G1.
I think that a perfect match would require a drag model tailored to a specific projectile over the velocity range that it will be used at.
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One problem you may encounter with some of the boattail slugs I have seen being marketed is that the boattail appears to be far too long and have much too large an angle on it for the airflow to be able to follow the shape. As a result, the airflow will break away and the drag will be little different to if the boattail was not there. The BC may still change due to the extra mass of the boattail. SLG1 assumes the boattail is working as it should.
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The rebated portion of the 22lr projectiles look sort of like the rebated boat tails of a lot of the cast airgun slugs. Even though the boat tails may not be working exactly as they should, maybe that’s why the RA4 ends up matching fairly closely for them.
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The shape after the rebate does look to be slightly boattail shaped, which may be giving a boattail effect. The only thing I would say is that boattails need a straight side shape, not a curved one as some of those appear to be. Putting a curved shape on the side means the air will break away at different points when there is some yaw, which will affect the stability and maybe the group sizes. Of course, if there is little or no yaw, then the effect will be much reduced.
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The Strelok update has been released, v7.2.0. Now you can export a drag functional as email (the .snr file), then edit it, and click it to import as a new drag function. He added a new feature on that page to View the drag function as a graph too.
I've attached the SLG0 and SLG1 profiles Igor sent back to me as the samples he used.
View attachment SLG0-1.zip
I've attached the SLG0 and SLG1 profiles Igor sent back to me as the samples he used.
View attachment SLG0-1.zip
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Thank you for the site, It will come in handy.Hard Air Magazine has a list of pellet BCs.
Ballistic Coefficients
Hard Air Magazine is publishing the World’s first comprehensive, structured and independent list of airgun pellet Ballistic Coefficients.hardairmagazine.com
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First of all, thank you for sending the SLG₀ and SLG₁ drag models.
They imported to Strelok without a problem.
Would you explain how you edit the .snr file? I had to change the file extension to be able to open it in Excel.
And when I wanted to import it back into Strelok like I did with the drag models you sent — it didn't let me.... (I had changed the file extension back to .snr before trying the import to Strelok).
Thanks,
Matthias
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First of all, thank you for sending the SLG₀ and SLG₁ drag models.
They imported to Strelok without a problem.
Would you explain how you edit the .snr file? I had to change the file extension to be able to open it in Excel.
And when I wanted to import it back into Strelok like I did with the drag models you sent — it didn't let me.... (I had changed the file extension back to .snr before trying the import to Strelok).
Thanks,
Matthias
If I remember correctly they are just a text file in some kind of CSV format, so open and edit with notepad. I would bet excel messes up the formatting when saving it. Any technical questions on file format or what certain things mean you'll have to reach out to Igor over Facebook.
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OK, I'll try to edit it with Notepad.
Thanks for that suggestion!
Your estimation that Micro$oft Excel messes up the file is probably correct!
Matthias
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Here is another table of BC's from HardAir magazine: https://hardairmagazine.com/ballistic-coefficients/Here is a BC Table — for quality pellets — in .22cal (attached below).
I have tried to assemble BC tests from all kinds of sources — and I have started just recently to run BC tests myself.
Many tests do not specify anything how they arrived at their numbers.
⁍ For example, JSB and H&N keep using the G1 drag profile — even though for many years we have the GA drag profile that was specifically made for round nose pellets.
Ballistician Miles Morris (screenname Ballisticboy) has refined the GA profile and gave us the GA₂ profile.
He also has given us a drag profile for typical airgun slugs and one for wadcutters.
⁍ Often, BC calculations are made using ballistic calculators that assume a constant drag coefficient — nothing could be further from the aerodynamic truth as drag increases greatly when approaching the speed of sound.
⁍ Because of the above mentioned large increase in drag at higher velocities (950/1000fps) it is important to publish at what velocity range the BC number was achieved. Rarely anybody reports that (thank you, HardAir Magazine for being exemplary in that).
⁍ Rarely, BC calculations take into account the atmospheric conditions — especially the air pressure — which is much lower at high altitudes — and greatly falsifies BC values.
So, here goes the BC table. The sources of the various BC numbers I have collected are referenced using a superscript number and letter. Some sources are true BC tests, others are just data collections (like ChairGun and Strelok).
Matthias
BC Table .22cal
View attachment 427857
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