Barrel harmonics and tuning

Discussion in 'General Airgun Chat' started by Knockedover, Mar 16, 2011.

  1. Knockedover

    Knockedover CSFTA Champ

    Joined:
    Apr 6, 2009
    Messages:
    991
    Location:
    Nr Portsmouth,Hampshire
    I've been interested in the effects of tuning barrel harmonics for some time, mainly centrefire based some years ago on a Browning rifle fitted with the BOSS system, and wondered as to its effectiveness in airguns. I'm aware that Dave Welham made (makes?) a tuner for his customised Anschutz rifles but have seen little else all bar occassional mentions in 10m shooting circles of using barrel mounted balance weights to vary harmonics. People have on occassion made reference to the weight of a muzzle brake or moderator possibly altering harmonics and being a factor in the increase, or decrease, of accuracy. Has anyone experimented in this department? What results and conclusions did you come to? I plan, when I have some spare time, to have a dabble myself using a barrel mounted weight on my spare free floated Steyr. If it will make much difference I don't honestly know but I'm curious to see if it will produce any noticable effects over extremes of adjustment and if it does to what degree it can be tuned. Thoughts on the subject would be much appreciated :)
     
  2. holly

    holly Well-Known Member

    Joined:
    Nov 8, 2008
    Messages:
    2,849
    Location:
    ISLE OF WIGHT
    Club:
    carisbrooke rangers
    Tried ?

    I have tried various muzzle weights/muzzle breaks on my ancshutz and settled on one of keith allens breaks .it gives me the best groups at 50 yards . reasonable every where else . i dunno if you can tune an air rifle for all the distances . ??? HOLLY
     
  3. Knockedover

    Knockedover CSFTA Champ

    Joined:
    Apr 6, 2009
    Messages:
    991
    Location:
    Nr Portsmouth,Hampshire
    I'll just be working on the premise that if its accurate at max distance it should be more so below that distance, or thats how it seemed when using the BOSS system on centrefires. If I can make any noticable difference in group size either way, good or bad, I'll try various ranges and see what the outcome is.
     
  4. tokoloshe

    tokoloshe Twang ****!

    Joined:
    May 2, 2009
    Messages:
    143
    Location:
    Hildenborough
    Club:
    Springfield & Seac
    Vinnie, have a chat with Ben Taylor, he's been down this road in quite depth.
     
  5. nurek

    nurek Member

    Joined:
    Apr 17, 2009
    Messages:
    114
    Location:
    London/Leighton Buzzard
    Club:
    Wendover ARC
    Vinnie,

    John Whiscombe used the Harmonic Optimization Tuning System (HOTS) on his latest Mk2 guns. The HOTS is an adjustable weight at the end of the barrel that screws in and out as required, it works, have a look at this thread on a US forum:

    http://www.network54.com/Forum/79537/thread/1289424930/Whiscombe+HOTS+-+ok+now+I'm+a+believer

    Also have a look at this article on HOTS:

    http://www.pyramydair.com/blog/2006/11/whiscombe-rifles-and-barrel-harmonics_28.html

    I like the Dave Welham system as it is more adjustable and the weights can be placed anywhere on the barrel, as placing them at the end of the barrel limits your adjustment as the weight is at the end of the ‘wavelength’ having kind of a pendulum effect.

    Mate of mine in Poland was after adding extra weight to his Rapid and has put weights on the barrel, have a look at this picture:

    http://www.strzelanie5.jpg.pl/prywatna_galeria_zdjec_strzelanie5_zdjecie16,1009804.html

    He has found that it has improved accuracy and made the gun less pellet fussy!

    There is an article in this month’s Airgun World about harmonics, it was written by a University Professor that developed the HOTS system for John Whiscombe.

    Piotr.
     
  6. RobF

    RobF Administrator Staff Member

    Joined:
    Mar 4, 2010
    Messages:
    11,975
    Location:
    Poole, Dorset
    Club:
    Parkstone Gun Club, South Dorset FTC, Southampton Buccaneers
    I think there is a difference between damping and harmonics...

    but they steyr i knew stuck them through the same hole at 50m anyway, so i'm not sure how it could be improved on.

    those examples dont seem to be giving that good groups as a final result, although there's an improvement, it's about on par with what a pcp should be doing anyway...

    sceptical... ;)
     
  7. chrispro97

    chrispro97 New Member

    Joined:
    Jun 10, 2009
    Messages:
    1,062
    Location:
    atherstone
    Club:
    purley chase ftc
    your bang rob ive got 10 metre weights tryed,then tryed strippers,air brakes flute tubes,nothing on barrel,and air breaks,the only thing i found if the stripper is not set for the pellets the groups opens out,so i only use a hydrographics break style,just to stop any kick to follow pellets to targets from 35 yards and out and the groups are only as good a the bloke pulling the trigger,can easliy do 5 pence groups at 55 yards off the knee ft style and better or tighter off the bench
     
  8. Scoch

    Scoch HOW!!!

    Joined:
    Sep 22, 2009
    Messages:
    466
    Location:
    Dundee, Scotland
    Club:
    Tayside Airgun Club
    I had a barrel weight on my Steyr Vin and swear blind that the gun def shot better with it on, took me about 3 hours to find the right position for it, moving it 1mm at a time you could see the groups open then close right down.

    Think I still have a couple of Steyr ones kicking about in the gunbox mate if you want to try them.
     
  9. RobF

    RobF Administrator Staff Member

    Joined:
    Mar 4, 2010
    Messages:
    11,975
    Location:
    Poole, Dorset
    Club:
    Parkstone Gun Club, South Dorset FTC, Southampton Buccaneers
    will be interesting to see though... i just think that perhaps some barrels may respond with a bit of weight on them :)
     
  10. m_pragnell

    m_pragnell New Member

    Joined:
    Aug 3, 2009
    Messages:
    11
    Location:
    devon
    On my steyr i found the adjusting of the stripper cone made a difference to the grouping. i wonder if that is because of the stripper functioning better or because even if its minute the change in the distance of what is a very small weight on the end of the barrel would have an effect on the harmonics, to be honest the rifle was very acurate anyway but with fine adjustment the groups are tighter.
    was also thinking ive heard a few fellow steyr owners down here say they had tried and then decided to remove what ever was on the barrel be it stripper or mfc as the groups got worse with them on so does putting something on effect the harmonics and that has a greater effect on accuracy.
    definatley an area of interest and would be happy to do some experiments with barrel weights if anyone has any to see the effect it has with and with out the stripper.
     
  11. Gibbs

    Gibbs New Member

    Joined:
    Jan 3, 2009
    Messages:
    388
    Location:
    North Cornwall
    I was told Steyr reccommend nothing on the end of their barrels because they have already fine tuned the barrel harmonics so I took the muzzle brake off mine and the groups did improve.
    But I am very interested in Chrispro's comments about a brake allowing him to see the pellet land, that would be very useful and might even be worth a slightly bigger group?:eek:
     
  12. chrispro97

    chrispro97 New Member

    Joined:
    Jun 10, 2009
    Messages:
    1,062
    Location:
    atherstone
    Club:
    purley chase ftc
    ive tryed barrel weights steyr 10 metre type made no difference at all sliding them or moving them by 1mm at a time,stripper wise i had a adjustable tried it in out altering as you should,and a barrel with nothing on a barley twist was just as tight at 55 yards with groups,alot is down to pellets 0500 08 mozzies put wicked groups out,so all ive got now is a air break hydro graphics type and groups are the same with a barley twist
     
  13. chrispro97

    chrispro97 New Member

    Joined:
    Jun 10, 2009
    Messages:
    1,062
    Location:
    atherstone
    Club:
    purley chase ftc
    groups stop the same with a air break alec and u can watch pellets past 35 yards out anything closer they go to quick cant see um
     
  14. RobF

    RobF Administrator Staff Member

    Joined:
    Mar 4, 2010
    Messages:
    11,975
    Location:
    Poole, Dorset
    Club:
    Parkstone Gun Club, South Dorset FTC, Southampton Buccaneers
    Brakes allow better follow through to be observed by dampening the recoil. What they cant do is solve a snatch shot being taken with the crosshairs still moving. The brake on a barrett absorbs 40% of the recoil of the .50 bmg round.

    Towards the end of the season, on the last 2-3 shoots, i managed to observe pellets in flight on 50x with the springer, and a lot of the landings... even on a stander... but you can't snatch on a springer and hit targets. That said, I still had no clue where some went...

    indoors last night, i could see most of my misses standing with the pcp ...:rolleyes: and a few in the air

    seeing pellets land is of great benefit, but i have made mistakes with splits flying across the kill and persuading me there is 40mm more or 40mm less wind than i aimed for...
     
  15. m_pragnell

    m_pragnell New Member

    Joined:
    Aug 3, 2009
    Messages:
    11
    Location:
    devon
    i shoot with alec so im sure he was one of the people who had told me steyr say nothing is best i just personaly feel the rifle looks better with something on the end of the barrel (im sure people wont agree just my opinion) so i went for a stripper with vents at the top and this takes out the last bit of flip or recoil (that tiny little jump) it has a moveable cone and when i first put it on the groups were worse than without it but with adjustment i believe the groups are tighter than before or atleast as good as it was without it. i like that it is completley dead now and also like how it looks but these are just my opinions. another point worth raising is the thread on the new lg110 ft shows the longer barrel and some sort of muzzle thing on the end does anyone know if thats a still air cone? if it is perhaps steyr have changed there thinking?

    atb

    martin
     
  16. RobF

    RobF Administrator Staff Member

    Joined:
    Mar 4, 2010
    Messages:
    11,975
    Location:
    Poole, Dorset
    Club:
    Parkstone Gun Club, South Dorset FTC, Southampton Buccaneers
    It does depend on where the flip is coming from as to the best solution. Walthers have a lot of recoil because their hammer is huge, so the recoil occurs before the pellet leaves the barrel, so a stripper/brake only works after the pellet has left the barrel and has air passing through it. So it moves, but the brake reduces that movement post shot.

    Another issue could just be vibration... often people think a smoother firing gun is a faster firing gun.

    But by moving the barrel down in the rig, the recoil path is straighter creating less turning action and flip, and so a stripper/brake may not be needed. Those that have their barrels up high courtesy of a deep fore-end, and a light grip will see more than those that have a tighter grip and lower forend (given the same butt offset).

    This maybe why steyr have changed their tune, although a lot of their sales waffle about harmonics was upset by simple poking like asking what happens if the speed of the pellet changes...

    Prone shooters will know that driving the shoulder foward can be inconsistent leading to shots going off the group, as the rifle reacts differently in the recoil to the shoulder. The same thing will happen with pcp's but not to the same degree, but given enough slack the bad habit can creep in and you will get odd flyers... the answer to what were the cross hairs doing from release to land on target can reveal a blank expression which means either follow through was not observed, or not possible to observe. Then you can work on the reasons why.
     
  17. dia6olo

    dia6olo Member

    Joined:
    Oct 29, 2009
    Messages:
    62
    Location:
    Leigh, Lancashire
    Airgun World has an article in this months issue (April) regarding barrel tuning, it appears to work and there will be a concluding article in next months issue :)
     
  18. Knockedover

    Knockedover CSFTA Champ

    Joined:
    Apr 6, 2009
    Messages:
    991
    Location:
    Nr Portsmouth,Hampshire
    Plenty of thought provoking comments and ideas so far:) Its interesting to see what people have experienced with weights, brakes, etc...seems some made a difference some didn't, but what variables become a factor for making something work and not work? Would a muzzle brake not only affect the barrel and gun movement but also the resonance? Could tuning the air gap in a stripper also be tuning the harmonics via not only weight distribution but the movement that the stripper causes?
     
  19. Knockedover

    Knockedover CSFTA Champ

    Joined:
    Apr 6, 2009
    Messages:
    991
    Location:
    Nr Portsmouth,Hampshire
    Interesting reading :) Thank you :)

    That would be handy :) Cheers Steve. I currently have a single 100g barrel weight but it would be handy to try out various settings with additional weight :)
     
  20. JEV

    JEV Member

    Joined:
    Dec 24, 2008
    Messages:
    308
    Location:
    Staffordshire
    Club:
    Purley Chase FTC
    Only 5p size these days, you must be going of the boil. More training required!!
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice