Barrel harmonics

[Artfull-Bodger]

The video here is a bit of an eye opener as to the barrel harmonics of an airgun. https://www.youtube.com/watch?v=RftoBqi_y-M&t=169s

What the guy has done is attach a laser to the end of his barrel and on firing filmed the laser spot on the target with surprising results, now bear in mind this is FAC rated so will be more pronounced but it gives a clear idea of how much movement and therefore the poi there is with an air rifle, also how useful it could be to experiment with muzzle weights to tune the barrel.

[krisko]

i think it is the whole gun moving, everybody knows the hw100 is rubbish at fac, because of the barrel and the small pre chamber.

people try to find and explanation for poor grouping, i am not conviced that you can bend the 15-16mm barrel by air pressure. high power does recoil yes but other guns can still group decently.

[blooregard]

people try to find and explanation for poor grouping, i am not conviced that you can bend the 15-16mm barrel by air pressure. high power does recoil yes but other guns can still group decently.

Newton and Pythagorus would probably disagree.

[Artfull-Bodger]

i think it is the whole gun moving, everybody knows the hw100 is rubbish at fac, because of the barrel and the small pre chamber.

people try to find and explanation for poor grouping, i am not conviced that you can bend the 15-16mm barrel by air pressure. high power does recoil yes but other guns can still group decently.

watch the multiple target shot at the end, the rifle is benched , they all exhibit the same movement, take a look at this if you think barrels cant move - https://www.youtube.com/watch?v=NR6AW3rQrTY, https://www.youtube.com/watch?v=FaW_Hs0B79c

what you have to remember is that target is at 30m so the tiny amount of movement at the barrel is amplified by the range.

[lensman57]

watch the multiple target shot at the end, the rifle is benched , they all exhibit the same movement, take a look at this if you think barrels cant move - https://www.youtube.com/watch?v=NR6AW3rQrTY, https://www.youtube.com/watch?v=FaW_Hs0B79c

what you have to remember is that target is at 30m so the tiny amount of movement at the barrel is amplified by the range.

I am not quite sure if the problem with some HW FACs is not related to the very long 24" barrel. Has anyone tried the gun with the shorter 16" barrel? It may not make 48J of ME but it could help its consistency.

A.G

[Matt]

I didn't believe in it until Jon Harris modded my Anschutz 9003 with a harmonic tuner, made a big difference turned average groups into great groups overall more consistent groupings.

Still can't get my head round it but am convinced it works.


Matt

[ballisticboy]

Videos which purport to show barrel harmonics are in the main very unconvincing. There are always important details of the experimental techniques missing many of which could be vital to a properly controlled experiment. They also miss the main point of any barrel movement and its effect on the pellet flight. Just because a barrel is vibrating it does not mean this will lead to an increase in dispersion, that will require a variability in the vibration which the videos do not show. Much of the barrel vibration shown will produce a bias in the mean point of impact not an increase in dispersion. The barrel harmonics will not have gross changes from shot to shot so should not produce large dispersion patterns. The difference in timing of pellet barrel exit is also too small to explain any large increase in dispersion due to barrel harmonics. There are other effects of the air pressure and pellet movement on barrels which can give rise to very high frequency barrel changes which affect pellet barrel fit and could lead to increases in dispersion but they are nothing to do with barrel harmonics.
I have said it before but really YouTube is not a good place to try to obtain accurate information on the science of shooting.