All Springer/NP/PCP Air Gun Discussion General > PCP/CO2/HPA Air Gun Gates "The Darkside"

Qb and crosman o-ring sizes and where to buy?


Does anyone have the sizes of the orings needed to rebuild a qb 79 and/or crosman/Benji maximus,disco,fortitude series? Trying to put together a kit so I'm not constantly ordering small kits for more money lol. McMaster Carr the best place to get them from or possibly captain o ring?

Sorry, I forgot I have to use Google search to find things here, found most of the o ring sizes already

The QB78 uses #113 o-rings for the valve and endcap. 

1.  valve -#113
2.  end cap -#113
3.  barrel -#012 [qty 3]
4.  .177 bolt M1 x 2.5 or -#003
5.  .22 bolt -#006

Buna-N in 70 durometer is fine for all of them except the end cap which needs to be polyurethane.  You can use Buna-N but it will swell and you'll have to swap it when changing cartridges (it will return to its original size after a while and you can re-use it).  The Buna does swell a bunch.  See pic.

I can't address the others as I've never been into one of them.



Thank you Jeff!

Dont anything about 79….but I got kits for my 78’s off ebay..enough for 2 rebuilds .22/.177…good luck


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