Fascinating video on pellet speed and power loss over distance

[andrewM]

Occasionally, I watch some of the shooting videos on Youtube, a number of which are interesting and informative.

I haver just watched this one:

https://www.youtube.com/watch?v=cyTZGOMSMUk

Airgun Pellet Speed Power Test: 0 to 50m .22 +.177- FPS + FT LBS - from AirgunGearShow.

It tells us that the ft/lbs loss of a 177 pellet is greater than that for a 22 - something that many of us already knew. However, it also explains - and this I found most interesting - that a 22 with a lighter pellet v a 22 with a heavier pellet (the same applies for 177), will result in the lighter pellet losing its energy (in ft/lb) so fast that this has already made an impact within 5m of the shot leaving the barrel.

Here is an example: Using Superdomes (14.5g) the ft/lbs is 10.83 at the point of leaving the barrel and the JSB Exacts (15.9g) are 10.82 ft/lbs at the point of leaving the barrel. However, at 5m, the S.domes have fallen behind already, at 9.57ft/lbs whereas the Exacts are at 10.39ft lbs. By the time we reach 40m, the S.Domes are recording 5.54ft/lbs against 7.05 ft/lbs for the Exacts.

It is worth watching this 12 min video.

It would be interesting to know how the trajectories vary and if there is a cross-over point, at which the lighter pellet falls below the heavier pellet in its trajectory. I wonder if any reader can advise? Many people buy the lighter pellets, such a S.Domes, because they expect the trajectory to be flatter than with a heavier pellet such as Exacts or AA, for example. But this might be an error, if the lighter pellet demonstrates a more curved trajectory.

Rgds
A

[Halimede]

School was a long time ago for me but...
Drag increases at the square of airspeed. A pellet has to shove air out of its way so loses energy. For a given speed and weight a wider pellet shoves more air so loses more energy but a heavier pellet (at said speed) has more energy to lose so slows, well slower. Hang on, I might need to think about this some more.

[Shed tuner]

superdomes are not a good example of a lighter pellet, as they have particularly poor ballistics. The Falcon Accuracy Plus / JSB express / RS are much better, and weigh even less (13.43 / 14.x grain)

[zephyr]

Ah, those were the days. I subscribed and avidly watched Giles’ YouTube channel. As he says at the end “…there are variables…”, “…take this as guidance, not complete fact…” and “…overall findings would play out…”. It would be much better (although expensive) to have multiple chrono’s set up, so you are measuring the same pellet thus eliminating variability between shots.

[Shed tuner]

when I've done this before, like most others, I have two chronos, one near the muzzle, and one around 35 yards. Allows you to calculate BC pretty well, and certainly good enough for comparative purposes.

[TonyL]

Thanks for posting, Andrew, although this won't be too surprising to many who may have read various posts on here before (especially when ballisticboy jumps in) and some excellent articles by Jim Tyler. As JB says, the Superdome doesn't seem to be a very efficient pellet ballistically. The BC is key (dictated by many constituents) and this also has a huge bearing on wind drift susceptibility . All very interesting stuff. The only way to get the true BC for a pellet in your own gun is to conduct your own tests, as it varies from gun to gun, but there are some handy charts available (giving a general idea) that make interesting reading, like the ones available on the U.S Hardairmagazine site.