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Hw100 Barrel Extra Grub Screw Mod

Discussion in 'Technical' started by Jeffsy, Mar 14, 2019.

  1. Jeffsy

    Jeffsy Busy Member

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    After some advice from anyone who has undertaken this mod.
    I’m keen to do this to mine.
    After floating the barrel, only option with a Hugget Shroud conversion, mine is a tad droopy.
    You can barely fit a fag paper between the muzzle end and, lightweight titanium ;), cylinder but the gap is larger at the breech end.
    Im convinced a 2nd grub screw above the barrel in the block would definitely bring the barrel back inline.
    One for @Blackmax or @HW100Tuning maybe?
    :up:
     
  2. HW100Tuning

    HW100Tuning Straight Pride

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    I seriously doubt the barrel is drooping. In fact it is almost impossible unless the block is damaged. So either the shround is drooping or more likely the air cylinder is being pulled upwards to make the barrel "look" like it is drooping. You'll notice the cylinder can be moved up and down easily as it doesn't actually sit against the block - there is an approx 0.5mm gap.
     
  3. themadspread

    themadspread Donator

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    cylinder out of line I would say or you would have a bad accuracy problem in front of or beyond zero
     
    Jeffsy likes this.
  4. Borisvanderput

    Borisvanderput Engaging Member

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    Turn the barrel 180 degrees and see how the gap is
     
    Jeffsy, cloverleaf and Marky-Boy like this.
  5. Blackmax

    Blackmax Pro Poster

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    As Steve said it's unlikely to be the barrel, they're 16mm think and very robust.

    The fixing system on the HW100 is fine and the effectiveness of a second grub screw a fallacy.
     
    Jeffsy likes this.
  6. josh9465

    josh9465 Active Member

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    For those that don’t believe it is necessary to have an extra grub screw, I say it’s helped me.

    With a grub screw it raised my poi 1.5 inches at 42yards.

    I installed this screw myself plus I milled a small flat spot on the barrel.


    [​IMG]


    .
     
    audi swift, bucketboy and Jeffsy like this.
  7. Two200's

    Two200's Engaging Member

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    Does this not just mean that 1 grub screw is working against the other though? So allowing another variable. Meaning that the bores inclination is changed by the position of screw A vs screw B.
    I can remember in the early days of the 100 - people would be able to turn the barrels when unscrewing the silencer. The first 100s silencers were slip on and not threaded, so this started to happen on mk 1.5's
    But nipping up the factory grubscrew seemed to eliminate that.
    I saw people discussing this when they first wanted to free float (remove figure of 8 rather than just remove the support O Ring) - which is going back a good few years now.
    I've not heard of many people doing this since - is it something that lots naturally do and Im unaware?
     
    Gunfun and Blackmax like this.
  8. Jeffsy

    Jeffsy Busy Member

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    Having had another look at it, as the action is out of the stock for a thorough drying after getting wet today, think you’ve nailed it. The cylinder has a tiny amount of “float” and under very light pressure can be moved.
    Taking into account what BM has stated and the above I have decided to scrap the idea of milling a hole and adding a second grub screw.
    :thumb:
    As for turning the barrel 180 degrees would that imply a barrel could be bent slightly? :eek:
     
    Blackmax likes this.
  9. HW100Tuning

    HW100Tuning Straight Pride

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    Not necessarily bent, just not machined concentric.
     
    Blackmax and Jeffsy like this.
  10. HW100Tuning

    HW100Tuning Straight Pride

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    I actually have a few 0.5mm thick delrin washers I made to fit the bottom of the cylinder... they take the slack up so the cylinder can be screwed down firmly against the block and then the cylinder remains square.

    Want one?
     
    Jeffsy likes this.
  11. HW100Tuning

    HW100Tuning Straight Pride

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    @Jeffsy
    Video I took of a new HW100 barrel in the lathe... showing how concentric they are NOT.


    For the HW100 it's best to get the offset pointing to the top.
     
    Jeffsy likes this.
  12. Bagster66

    Bagster66 Engaging Member

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    I would like a delrin washer as I have this on my.20.
    If you have any spare can I add one to the titanium tube I am getting from you.
     
  13. Jeffsy

    Jeffsy Busy Member

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    Holy cow Batman! :eek:
    Whilst that looks horrendous what does it actually do to the pellet flight? :shrug:

    That’s most kind sir, yes please!
    Shall I email Mel?
    :thumb:
     
  14. HW100Tuning

    HW100Tuning Straight Pride

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    Nothing, the bore is still straight, it's just not concentric to the OD. It can mess with POI at different ranges if it points to the side though. Hence better if it points up vertically.

    Yeah email Mel.
     
  15. Borisvanderput

    Borisvanderput Engaging Member

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    @HW100Tuning

    Could you sketch the dimension of the delrin washer? I can then machine one for myself, I'm too far away to ask you to send me one.
     
  16. Jeffsy

    Jeffsy Busy Member

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    Thanks Steve that makes sense.:thumb:
    Is there an easy trick to check concentricity without a lathe?
    I suspect the old rolling a snooker cue across a table to see if it’s wonky might not work here? :D
     
  17. HW100Tuning

    HW100Tuning Straight Pride

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    Think about it.... take cylinder off and the thread is m20x1... so the ID is 20mm. The cylinder diameter is 37mm, however the block isn't that wide and you don't want the washer wider than the block. So measure the width of the block, (haven't got on on me at present) so lets say it is 34mm ... then the OD would be 34mm. Width 0.5 - 0.6mm.

    Edit******
    Just measured Block 29.4mm...

    So 29mm OD x 20mm ID x 0.5mm CS (cs = cross section - thickness)

    :thumb::thumb::thumb:
     
    Last edited: Mar 16, 2019
    Borisvanderput likes this.
  18. HW100Tuning

    HW100Tuning Straight Pride

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    Just buy a lathe you tight g#t lol ;)

    Easy way to set it up for your gun. Get a bore sight laser. Take barrel screw out, put gun on a stand (put the cylinder and stock back on temporarily). Put laser in, point at a wall and turn the barrel around 360 degrees in small stages (you can mark the wall with a pencil). Find the top most point on the wall where the laser hits and then mark the barrel at the top most point with a felt tip. (I put masking tape round the barrel so the mark can be seen easily).

    Mark sure when you clamp the barrel in with the mark at the top.

    I have a laser bore sighter if you need to borrow one.
     
    Last edited: Mar 16, 2019
    Jeffsy likes this.
  19. Borisvanderput

    Borisvanderput Engaging Member

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    Thanks. For me to take the cylinder off means to empty the air out of the XL titanium cylinder, it's the hw100tuning's with the huma reg in it:). So I'll take it off once the washer is ready.
    BTW the block width is 29,2mm.
     
    Last edited: Mar 16, 2019
  20. Jeffsy

    Jeffsy Busy Member

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    Ha! Not tight just poor because I keep buying shiny things ;)

    Thanks for the top tip! A simple but very effective solution :thumb:
    I have a crappy fleabay bore sighter somewhere that should work.
     

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