The Edge Of Ballistics

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CAPTAINQUINN

CAPTAINQUINN

Member
Aug 12, 2018
9
1
New Hampshire
I found this quite interesting. Maybe some of you folks will as well. I have been experimenting with the point when a projectile “breaks”. Meaning when its forward momentum has dropped enough to make its ballistic coefficient go to $hit and the projectile starts to tumble and do some funky stuff. The rifle is an FX Royale 400 in .22 caliber with a 60 power scope at 50 yards. I dialed the power down on the rifle to its absolute minimum. A 16 inch drop from my normal zero. The pellet breaks at approximately 42 yards. The last 8 yards is just guess work and luck. Sorry about the video resolution. Filmed on an IPhone 6s in Slo Mo and then slowed down even more in post production. I would estimate 940 frames per second. The bitter edge of ballistics. My chronograph is temporarily out of order (because I shot it) so I can only estimate the muzzle velocity. 540fps. How do you control the uncontrollable?

Cheers

Ian.

https://www.youtube.com/watch?v=Q0keJTEGHBg&feature=youtu.be
 
Who wants to do the ballistics calculation that tells me what the stability failure speed was at 42 yards. Then please calculate the yardage when a pellet slows to that same failure speed given a muzzle velocity of 850fps. Just guessing from the many "golf ball challenges" that it might be well beyond 100 yards.

I loved the video and am constantly amazed at new technology. Thanks for the iPhone application expansion. 10 years ago you would have needed a large investment to capture that, now we just do it with an iPhone?! Is there a chrony app yet? Coming soon I'm sure. I retired my film cameras long ago, going to retire the 10 year old DSLR next. Sorry, rambled off topic.

But what about that iPhone Chrony app ?!
 
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Not all heroes wear capes. Hello dgiannandrea. I have journeyed through the land of BNC an F connections. I have been in the valley of VHS. I too am stunned with this new technology...and I like to shoot air rifles in my back yard. I think the scope footage is cool when they let go at 42yrds. I will post a pic of my Hi Tech scope camera mount. Cheers.

Please post a pic of you rifle.

Ian
 
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I think this is why the UK folks don’t use smoothtwist, at low power it is not shooting straight. That is around 11fpe



are you sure it is doing it only from 40yards onwards? I think it wobbles a bit earlier too



nice video, to me it seems the twist is still more than 1:44 or some one posted here recently, are you sure your pellets are not damaged by the pellet probe or something?
 
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You're a man after my own heart, Cap'n Ian! I am fascinated by ballistics. Particularly with the exact issue you raise. BC is such a complex metric to calculate; a plethora of dependent and independent variables are involved. Of course, velocity is one of them. I have noticed that at the extreme outer limits of my hold-over, the pellet is not tracking my Chairgun numbers. It's hard to tell if this is just the exponential result of my shooting mechanics errors or if the BC just went fakakta due to the decrease in velocity. (Of course, there are many other explanations such as windage, pellet imperfections, air regulation issues, etc.)

I used to have a WC Mk1 .25 that shot spot-on out to 100 yds per Chairgun; but as I ventured more and more out to the limits of my scope mil-dots (134 yds), there was a POI drop-off from what Chairgun said the hold-over should be. What was interesting was that my field-tested hold-over adjustments were consistent. For instance, when Chairgun said the hold-over at 125 yds should be 4.12 mil-dots, and the actual hold-over required turned out to be 4.27; that 4.27 remained consistent over several shots. This makes me believe that the BC as a function of velocity broke at that distance. In other words, the BC I entered into Chairgun was valid out to 100 yds; but beyond that, the BC dropped.

I recently bought a Pulsar HP .25 that delivers more fps than my WC with the same round. It will be interesting to see if I experience a commensurate POI drop at the same fps. This would tend to confirm my BC theory. 
 
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