ScopesAndAmmo.com Store Logo

+ Reply to Thread
Results 1 to 4 of 4

Thread: Misdrilled Disco Tube

  1. #1
    Moderator rsterne's Avatar
    Join Date
    Wed Dec 7 2011
    Location
    Coalmont, BC
    Posts
    1,261

    Misdrilled Disco Tube

    I recently purchased a Disco tube, and when I went to install the valve found out that the hole for the transfer port, and the two 4-48 holes for the middle breech screw, were drilled about 0.028" too close to the back end of the tube.... The port in the valve didn't line up, and the breech screw hole was far enough off there was no way you could install a breech.... Fortunately, I had to enlarge the transfer port hole anyway, and I was doing a custom breech, so I drilled and tapped a new screw hole in between the originals and will make the breech to suit.... Without modification, this tube was unserviceable, but somehow made it through Crosman's QC....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal:
    .177 Diana 34, 1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 22XX PCP 8-shot Carbine, 2260 PCP Rifle (50 FPE), Hayabusa PCP, .22 B-26, DAQ .308 Exile

  2. #2
    Senior Member Doc Sharptail's Avatar
    Join Date
    Sun Jan 1 2012
    Location
    Up The Escarpment
    Posts
    320
    The wonders of automated mass-production never cease to amaze me. Q/C seems to be hit and miss with everything these days- especially computers.

    I suppose that tube would have been tripped up if the factory had tried to assemble it into a complete unit.

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  3. #3
    Moderator rsterne's Avatar
    Join Date
    Wed Dec 7 2011
    Location
    Coalmont, BC
    Posts
    1,261
    Yep, they couldn't have bolted a breech on it, even if they tried to ignore the badly aligned transfer port....

    Bob
    Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
    Airsonal:
    .177 Diana 34, 1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 22XX PCP 8-shot Carbine, 2260 PCP Rifle (50 FPE), Hayabusa PCP, .22 B-26, DAQ .308 Exile

  4. #4
    Senior Member Doc Sharptail's Avatar
    Join Date
    Sun Jan 1 2012
    Location
    Up The Escarpment
    Posts
    320
    My newest pumper- a 13-22 has the holes for the pivot pin mis-drilled as well. It's okay for the cup piston and factory plastic block with ovalized holes, but for a flat top with one of the old "Crusty" brass pivot blocks, it's a total no-go. I'm pretty bummed over this. I had wanted to shoot it tonight with the little Weaver I had picked up Saturday. I'll give it another shot tomorrow- try and get a 24" bbl 13-77 that isn't holding, up to par...

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

+ Reply to Thread

Similar Threads

  1. What O-rings to get for QB78 valve and gas tube end cap?
    By Dukemeister in forum Co2 and Pre-Charged Pneumatic (PCP) guns.
    Replies: 10
    Last Post: Nov 11 2012, 09:27 AM
  2. 22xx tube bleed hole and Disco valve
    By sholo in forum Co2 and Pre-Charged Pneumatic (PCP) guns.
    Replies: 27
    Last Post: Sep 30 2012, 05:04 AM
  3. WTT AR 2078 air tube with key for QB 78 trigger
    By paddyfritz in forum For Sale
    Replies: 5
    Last Post: Jul 20 2012, 12:04 PM
  4. QB78d long Co2 tube
    By just missed in forum Wanted/Where to Find in Canada
    Replies: 13
    Last Post: Mar 13 2012, 03:57 AM
  5. 3000 psi tube QB78
    By remtom1200 in forum Co2 and Pre-Charged Pneumatic (PCP) guns.
    Replies: 64
    Last Post: Feb 17 2012, 04:01 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts