The barrel thread

Discussion in 'General Airgun Chat' started by RobF, Oct 15, 2015.

  1. RobF

    RobF Administrator Staff Member

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    Seeing as some (ie me) are playing with barrels I thought it useful to archive some basic findings from blanks purchased (all choked, all .177)

    BSA 12 lands, clockwise (from breech to muzzle), 1 turn in 16"

    Lothar Walther 12 lands, clockwise (from breech to muzzle), not measured twist rate yet, 600mm long

    CZ 12 lands, clockwise (from breech to muzzle), not measured twist rate yet

    I'll also put up some macro shots of the rifling shapes which varies enormously when I get 5 mins.
     
  2. NeilM

    NeilM Well-Known Member

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    I have long felt that land shape and condition play a massive part in both accuracy and windage.

    I currently have a Pro-T which I have just started barrel testing on, and presently have.

    Standard Pro-T 'short' (Lothar Walther)
    MK3 Pro-T 16.5" (LW)
    Long 21" RN10 (LW)
    BSA 15"
    Anschutz 19"
    Career 20", not yet machined to fit Pro-T.

    I want to add a CZ barrel to the collection at some point.

    Not sure what conclusions I will come to, or when, but you know, a chap's got to have a hobby.
     
  3. Tench

    Tench WHFTA World Champion 2016.

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    Rob I have measured a lot of BSA production rifle barrel twist rates over the years and only ever seen them in the 18.5-19" range, makes me wonder whether yours is actually a bsa barrel?

    I am dubious about the claimed origin when barrel blanks are unmarked, I recently fitted one which was bought as an HW100 .22 barrel blank, but it had the wrong number of lands!

    I get the CZ barrels at 19" twist too, I have only measured those factory fitted to the S200.

    Some I can add are the Barley twist LG100 barrel I had which measured at 15.5" twist rate

    Anschutz 8002 S2 barrel which has a 19" twist rate too. Lots of rubbish around the net about these not being suitable for 12 ft/lb due to the twist rate being designed for 10m when actually they similar to many .177 barrels and work very well in a UK converted rifle.
     
  4. Dave Ramshead

    Dave Ramshead England HFT Team squatter

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    I have a cz barrel machined for a pt, I don't think it gave any advantage over the 21"rn10 barrel apart from it prefers different batches of pellets compared to the rn. I haven't found a batch of pellets yet that go equally well in my small collection, maybe that's the search for holy grail.
     
  5. RobF

    RobF Administrator Staff Member

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    I didn't purchase it, but the chap who did bought it from the shop who said it was. The shape of the rifling is very similar to the BSA video and another BSA barrel we had on loan.

    We can double check the measurement, but i'd expect to it only being a slower rate if the plug slipped. We're measuring it with a mark on the barrel and a mark on the rod with a tight VFG... once it rotates once we measure the distance the rod has moved.
     
  6. mr dink

    mr dink Member

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    I have heard your collection has increased Dave how are you liking the trip to the dark side.:D
     
  7. hmangphilly

    hmangphilly The Doctor

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    it was a pukka one mr tench
    one of a pair from knibbs about a year ago

    oddly the two barrels have different rifling patterns one has v shaped grooves , the other more wedge shaped

    [​IMG]

    this bsa ........1in 16,
    cz s200 ........1 in 16
    super top secret diana barrel ( if i told you , i'd have to kill you ):D......1 in 14
    std steyr.......1 in 12

    proper quick measurements , ...i think jon harris posted his twist rate findings somewhere....

    good pic off my phone hey ?

    I'd better double check these findings , they're miles out from mr tench's ...........
     
    Last edited: Oct 15, 2015
  8. hmangphilly

    hmangphilly The Doctor

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    hey mate , they're clockwise from breech to muzzle too :eek:o:eek:o:eek:o:eek:o:lev:lev:lev:lev: :D:D:D:D:D

    or as you would say ......lol..........:)
     
  9. matt goodson

    matt goodson New Member

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    I wonder if the quicker twist rate is the reason that steyr shooters are always having to clean barrels out every third shot.
     
  10. RobF

    RobF Administrator Staff Member

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    Need to check my 550 steyr standard...

    and my LW 600mm
     
  11. hmangphilly

    hmangphilly The Doctor

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  12. Tench

    Tench WHFTA World Champion 2016.

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    I use an aluminium welding rod to measure the twist rate, flatten one end so it is a very snug fit across 2 rifling grooves, then cut it down to about 20" long and bend 2" up at the opposite end. Feed it into the barrel until the sticky up end is either horizontal or vertical, measure then move it in or out until it has turned 180 deg and measure again, take one from the other and double it. Unless you have a very long barrel you wont see a full rotation.

    Hammer forged barrels could have a variation in their twist rate from different batches as the barrel grows in length 10-15% as the metal is displaced longitudinally while being forged down onto the mandril, so machine setup could cause different growth and therefore the length in relation to a full twist.
     
  13. RobF

    RobF Administrator Staff Member

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    Do yours come from the same source? I'm wondering if there's other batches out there? Interesting to see a variation across a brand. I wonder what the new ones are?
     
  14. Tench

    Tench WHFTA World Champion 2016.

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    I was once told by Simon Moore at the BSA factory that only barrels destined for installation in a production rifle have the branding stamped on them, and barrels that leave the factory as just barrels do not, but I am sure I once bought a .25 barrel that had the stamp?
    They used to advertise their rifles as having a 17" twist. If the machine is set up to rotate the barrel at this rate during manufacture but it grows 10% in length during the process that would equate to the twist rates I have measured them to be. All the ones I have left the factory installed in off the shelf production rifles, the most recent is less than a year old and as far as I know have not changed in twist rate in recent years.
     

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