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.224 cal Slug Ballistics Coefficients

Started by rsterne, June 24, 2023, 03:02:37 PM

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rsterne

To continue my slug testing, I used the unregulated version of my custom Sporter I built a few years ago, in .224 calibre.... It has a 9" twist TJ's barrel, and can run on 300 bar (4350 psi), but for this testing it was tethered to a regulator set to 3800 psi.... Here is a photo....



I used a selection of cast slugs I had on hand, shooting them over my LabRadar as I did with the .257 Condor, with the following results....



I have shown both the BC(G1), which is the most commonly used, and also the BC(RA4), which is a much better fit for these slugs.... Those BC's are in Red Bold, and I recommend that you use those, along with using the RA4 Drag Model in your Ballistics Calculator....Do NOT mix the numbers between G1 and RA4....

As expected, the heavier slugs, with the highest Sectional Densities, had the best Ballistics Ceofficients.... I actually expected them to come out of the muzzle with more energy than they did, but I think I had the hammer strike just a bit light, limiting the dwell on the heavier ones.... In shop testing I was getting nearly 1000 fps with the 61 gr. slug at the same pressure!.... and I forgot to bring any tools to the range to adjust it (it is deep inside the rear stock and tube).... I was not shooting for groups, just concentrating on hitting the paper to get data from the LabRadar, but the 45 gr. slugs showed the best "groups" this time around.... I think that readjusted for the heavier slugs, they may show better.... I have designed a 60 gr. BBT that NOE will be making (eventually) that I hope will be perfect for this rifle....



Anyways, that is the data I have on a selection of .224 cal slugs, I hope you find it useful....

Bob
🇺🇦    I support Ukraine and their struggle to remain free!    🇺🇦

JungleShooter

Bob,

I love the detail and determination how you go about your airgunning and your airgun writing/publishing. And how you produce hard, scientific data.


You're a model for many of us who often just plink about and then — when asked for advice or an evaluation — just say:
"Do this!"
"Don't do that!"
"This one is good!"
"This one is bad!"

All with the whole-hearted conviction that rests on hunch-ientific evidence and bias-perience rather than hard data and logical deduction.



In my own journey so far I have only collected "hard data" that was easy to come by: specs of stuff I wanted to buy, usually in tables to easily compare models side by side:

▪ 3 Scopes specs tables (200+ scopes)
▪ Silencer specs table (50+ moderators)
▪ BC table of .22cal pellets
▪ Available slugs list in .22cal
▪ Bullpups photographic list
▪ Hollow point pellet specs table .22cal
▪ Adjustable scope mounts and rails table 30mm
▪ Hollow point expansion data as found on the internet .22cal



What I am lacking is producing new data like you...! 😄

● I started with measuring hollow point expansion in game at different impact velocities.
Need to get back on that.


● And I feel we really need data on the  BC of hollow points — since their impact velocity is so important — which makes their BC so critical.



Thanks for blazing the trail, Bob. God bless.  👍🏼

Matthias