Author Topic: Hahn Super BB Repeater Refresh  (Read 287 times)

CraigH

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Hahn Super BB Repeater Refresh
« on: May 25, 2018, 04:19:54 PM »
Well it is a CO2 gun, albeit at the low end of the scale, so I posted here.   If it should be elsewhere, please move as necessary.

I’m not much of a BB gun fan, but the Hahn Super BB Repeater is quite impressive compared to the Daisy 25 I had in 1960.  A friend of mine had one and it was the envy of we 10 to 12 year olds.   I bought one in fair to good condition recently, defined by many sellers as very good to excellent.   I replaced the o-rings and gave it an external refresh.

All the painted parts (barrel band, lever, and the two vertically separated receiver sections) are refinished with satin black Krylon paint (the lever of course is scratched with its first operation).   All the screws were smoothed with files and polished with 400 grit sandpaper.   The wood was without any chips, so refinishing was easy.   This example had the flat-ended buttstock – I’ve only seen a few images with this stock.   It was a bit clunky looking so I changed to a crescent shaped end.    The fitment of the stock to receiver was tightened up with J-B Weld.   It is stained with a mix of 5 parts chestnut to 1 part American walnut and finished with satin polyurethane.

I polished the transfer block passage a bit – no work on the valve which fortunately sealed well and did not need work or disassembly.   A chrony run with the hammer spring set to the position three (there are four positions) showed pretty good power.   The second of three shots in the 500 fps range was 527 fps.   Subsequent shots were in the 490’s and 480’s, but the trend was steadily down, so I set the hammer spring to position one.   Gas pressure was lower now, but there was not a huge difference in velocity.   Next step was to start a string at hammer position one with a new cartridge.    That produced a string of 458.6-476.0-481.7-477.0-480.3-467.6-467.3-480.2-457.2-455.0 fps; those ten shots show a modest desirable curve, but then velocity dropped to 433.2 fps and the remainder of shots steadily dropped to under 400 fps.   I noticed a bit of gas exiting by the external hammer, so there is probably gas escaping past the valve stem.   I do not known the old advertised velocity of the Hahn SBBR, but these numbers seem reasonable so there is probably a good seal through the transfer block, and the reason for low good shot count is the valve stem.   Perhaps cut for an o-ring or insert a finely fitted bushing.    However, the nose of the valve is of small diameter – see internals image.   Oh, and it did not have the hammer cushion located in the upper rear of the receiver.   I'm not sure of its design so I don't know if that might have an effect similar to o-ring stacks at the rear of valves.

But any such work is for the future.   And, it appears the rifle could be set up to use two CO2 cartridges with a Model 600 piercing cap and a simple spacer between butt-to-button CO2 cartridges.   A lot of other air guns will have priority though.


  • Lone Tree, Colorado
Craig

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Hahn Super BB Repeater

Alan

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Re: Hahn Super BB Repeater Refresh
« Reply #1 on: May 26, 2018, 06:13:40 AM »
Good job. BB gun or not, it is a nice looking.
  • Roswell, New Mexico
Alan

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Christopher

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Re: Hahn Super BB Repeater Refresh
« Reply #2 on: May 27, 2018, 05:48:00 AM »
Great work!

Thanks,
Chris
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