GTA

PCP - HPA - C02 Gate => QB-7X Gate -W/Co2 & HPA => : iconoclast January 08, 2009, 05:55:06 AM

: QB78D degassing hole
: iconoclast January 08, 2009, 05:55:06 AM

I saw on Archer Airguns site a picture of the AR2078 tube with the degassing hole.
Well, I thought what a nice feature to have instead of having to dry shoot multiple times.
So, I drilled a 7/32" hole in the tube just aft of the back end of the hammer when it's at the uncocked rest position.
My plan was to use a #3 square drive screwdriver to pry against the hammer back end in a forward direction.
Prying the hammer forward will open the CO2 valve.
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Well, I got to try it out today and it sure does work nice.
Certainly, a nice feature to have.
Makes it quicker to change out CO2 cartridges.

: RE: QB78D degassing hole
: CaptRussell January 08, 2009, 02:29:08 PM

Cool .... do you have pictures?

: RE: QB78D degassing hole
: iconoclast January 09, 2009, 03:04:41 AM

Here is a picture of the degassing hole in the QB78D.
I determined the hole position by removing the stock and trigger.
With the gun uncocked, I looked at the hammer position through the tube bottom slot.
I aligned the degassing hole forward edge to the hammer back edge where the spring enters.
I use the square screwdriver flat edge to gently push the hammer forward by pulling back on the screwdriver.
In other words, I'm using a lever action with the screwdriver.
This is different than the AR2078 key which apparently uses a rotating cam action.
It only takes a slight amount of pressure to move the hammer forward.
This opens the valve and the CO2 pressure is released.

: RE: QB78D degassing hole
: Stephen Archer January 15, 2009, 01:20:38 PM

Very interesting mod!

Yes, the AR2078/A de-gassing key does work by using camming action to push forward the hammer and open the valve, just as you describe.

Stephen Archer
Archer Airguns Inc.
http://www.archerairguns.com
http://www.youtube.com/ArcherAirguns

: My Crosman 180
: cole5169 February 20, 2009, 03:38:51 AM

has a hole in the cocking knob (back of the gas tube).  You can push the hammer forward with a small allen wrench to do the same thing you're talking about.  I thought that was a neat touch back then, and wondered why everyone (mfr's) seemed to give up on the idea.  Much handier than "cock-BLAM, cock-Blam, cock-blam, cock-pffffffff"!

I like your fix, think I'll try it out, too!