Cheapest thing to get the power up on a QB78

[Toddspeed]

Do a search on this forum for “$200 PCP”, follow the first few pages and you can get very good power levels without spending a dime.

DO NOT increase spring tension, as stated by others that will only waste gas.

In my opinion (my QB78s .22 shoots 16 grain pellets at 630-650 FPS for over 14 ftlbs) the breech seal is first, I use the Crosman one others have suggested, then enlarge the holes the gas flows through on its way to the barrel, try to make them all the same, about .177 or .118, I used a hand drill and Drexel tool. Greatest thing about the QBs is doubling the power with out spending a dime.

One suggestion though, if you plan to convert to HPA later, think seriously about a QB79, it will make the conversion MUCH MUCH easier. If you get a 12 gram adapter for the QB79, you’ll be able to able to use the same CO2  capsules the QB78 uses until you are ready for HPA.

[Ribbonstone]

Cheapest?...likely just changing the transfer port to a bit of icemeaker tubing, spacing  the striker spring forward for a bit more tension, and keeping the co2 rifle warm would likely do 12 foot pounds.

Cheap...wouldn't cost anything at all if there is enough slack in the icemaker tubing likely already on the 'fridge.

It is winter (at least on this side of the Equator), and keeping co2 warm and up to normal pressure while out hunting.


Are a whole lot of things you could do...that require tooling, new parts,lots of patience/skill/time to really get them up to high power...can get all into that as the need and the urge hits you,but to get to 12 foot pounds right now,doesn't really have to cost anything.

I reversed a lot of the stuff done in the past to one I converted to 5mm.  Basically reverse evolved  it back into a standard 12gr. rifle using a standard valve.  Ended up at 12-13 foot pounds (depending on the pellet).

[PG in San Diego]

Cheap...wouldn't cost anything at all if there is enough slack in the icemaker tubing likely already on the 'fridge.

I am going to file this one next to "You can boil your toothpicks, they are reusable!"  J/K 

I can just see my wife rolling her eyes as I try to explain to her why I'm cutting the icemaker line. 

[Ribbonstone]

Most installers go on the long side of thing...not wanting to end up short, and time is moneys....so usually end up with a loop of "extra" ice maker tubing taped to the back.  rather than haul my butt to the hardware store,I just disconnected it...cut off 4-5 inches...reconnected it...and had  enough tubing for something like 30-50 ports.

I just ram thesmooth end of an appropriate drill bit into the tubing and rotate-cut it even with a box cutter.

For a striker spring shim...normally use washers.

For 12 foot pounds,it's a lot easier in .22 than in .177...but the same two simple things can get you there in something like normal room temperature (lets say 70-74F).


have converted a few to HPA, tow to PCP, some to tanker co2, etc. But ended up with the most use for one (that 5mm) as a plain-Jane 12gr.QB78 running at about 12-13 foot pounds.....basically Sheridan "C" power without the pumping.


LAST thing I want to do is to discourage a new shooter. If 12 foot pounds is the goal (which isn't a bad goal for a co2 rifle) can do it with minimal changes.