All my rifles and pistols mostly springers rangeing from cheap Chinese to expensive German

Monday, 7 May 2012

XS78 CO2 Rifle .22 (QB 78)

The XS78 .22 CO2 rifle is probably one of the most mod-able rifles around, the standard format out of the box takes 2 x standard 12g powerlets and power will be any thing from 6lb to 9lb , they usually shoot accurately out of the box. The modifications you can do to these rifles are almost limitless and every one ends up with a  unique rifle. Below are the mods  I did to 2 such rifles my own and my sons.

Strip down - https://docs.google.com/open?id=0B4hV3nw-qXdnUU1zaXh0emsxM00  this link takes you to a full strip down guide.

Tune up - First job is to get the power up and smooth everything out to get consistency. In the UK  we are limited to 12lbs , for a .22 gun  you only need to change the transfer port, remove the filter in the valve, polish the internals and bolt, open up the bolt probe using a dremel and change all the seals. You will need to purchase a chronograph or get access to one (£60.00) so you can check you are not over power, it is very easy to go over power !  . CO2 is effected by temperature, the warmer the day the more powerful the discharge and on a cold day the power will be down, you need to make sure your gun will not go over 12lb on a hot day - usually it is advisable to tune up to about 11lb at room temp and check on a hot day with the chrono. Seals and transfer ports  can be purchased from https://www.youtube.com/watch?v=uY1WjhJPFRk  these are the best quality and a good price.

the above shows you the parts to polish and de-bur , this will make the gun smooth, you need to lube properly with moly grease on metal parts and silicon grease on the rubber seals , this protects the seals from the CO2.

New stocks - The most dramatic change you can make visually is to change the stock, the Webley AGS stocks are readily available, cheap and do not take much work to fit the 78 action. Below are the 2 styles of stock fitted to our guns.

With these stocks you get a gap left at the back of the action , this can be filled with wood or metal to finish it off , I decided to put something useful in the gap --- a shot counter. the .22 guns  will fire approx 50 shots on 2 capsules, it is best to store these guns charged with CO2 so I click each time I fire and when I get to 50 its time to change the capsules, also means when I put the gun away i know how many shots i have had when I use it again.

This modification makes the gun multi-shot , they work well, all you need to do is put high mounts on your scope . .22 gives you 6 shots.

I highly recomend these guns they are good value recoiless guns that are easy to work on and make your own. The only word of caution is that the .22 can easily go over power so make sure you have access to a chronograph. The .177 is harder to get up to 12lb but can be done.


  1. I feel for you guys over there who are stuck with the Foot lbs limits. Here on the US the QB78 is modded for power 90% of the time and hit 15-17 FPE. Kills shot count, but with bulk fill that's not a problem. One guy over here is pretty much the QB78 guru for modifications and pretty much tunes em to fit.

  2. Really informative and useful information.

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