Qb 79 RVA power adjuster

[Jayrotx821]

Do any of y'all make/have/know where to purchase a power adjuster for qb79?  Do you know if Hajimoto's super tune kit work on the qb79?

[SwampHunter]

I think nervoustrigger did a writeup on how to make one

[mackeral5]

I always convert my QB end caps to Crosman style.  Drill the breech for the upper screw and use a crosman end cap or premade crosman RVA.

This allows for much easier assembly as well......

Note this old double tubed .357 equipped an externally adjustable SSG similar to what is pictured below. 





Here you can see the rear breech retention screw, along with some other big-bore QB mods such as the bolt slot modded, one component of a system of mods allowing for full bore porting and retractable bolt....  Note this SSG is not externally adjustable.  Preload and gap are set while disassembled.

[SwampHunter]

I always convert my QB end caps to Crosman style.  Drill the breech for the upper screw and use a crosman end cap or premade crosman RVA.

This allows for much easier assembly as well......

Note this old double tubed .357 equipped an externally adjustable SSG similar to what is pictured below. 





Here you can see the rear breech retention screw, along with some other big-bore QB mods such as the bolt slot modded, one component of a system of mods allowing for full bore porting and retractable bolt....  Note this SSG is not externally adjustable.  Preload and gap are set while disassembled.

Do you have any post about this build?

[Goose]

That's a cool mod.

I went a different route.  The .22 QB78 was shooting 14.3g pellets at close to 600 fps after it was cleaned up and I wanted more shots from the cartridges.  An o-ring on the poppet-stem where the hammer strikes it eliminated hammer-bounce and gives me an average of 504-fps from over 70 shots per set of cartridges.  Pic attached.

Cheers,

J~

[mackeral5]

I always convert my QB end caps to Crosman style.  Drill the breech for the upper screw and use a crosman end cap or premade crosman RVA.

This allows for much easier assembly as well......

Note this old double tubed .357 equipped an externally adjustable SSG similar to what is pictured below. 





Here you can see the rear breech retention screw, along with some other big-bore QB mods such as the bolt slot modded, one component of a system of mods allowing for full bore porting and retractable bolt....  Note this SSG is not externally adjustable.  Preload and gap are set while disassembled.

Do you have any post about this build?

I'm sure there are post(s), but ultimately I was never content with the build.  Don originally designed the barrel bands for a Disco based build, which placed the barrel closer to the tube than a QB.  In turn the barrel was slightly bowed/bent between the breech and rear barrel band.  Not to mention it was heavy.  Not to mention porting between the upper/lower tube was equivalent to .25, which made it less than ideal for .357.  Not to mention the platform simply is not stable enough to produce what I would consider acceptable, repeatable, stable accuracy at 275-300fpe.......and so on...  Ultimately this one was reduced to its components and parted out across other builds, with the double tube system going to another GTA member.

[Jayrotx821]

Interesting.  I'd like to be able to adjust it externally.  I may have to try to make my own.  Not sure how difficult drilling that steel cap will be.

[nervoustrigger]

I may have to try to make my own.  Not sure how difficult drilling that steel cap will be.

The end cap is mild steel.  Not at all difficult to drill and tap, though it is a long part so I prefer to do it at the drill press but a hand drill will do if that's what you have to work with. 

A #10-32 is what I got into the habit of using.  The threads carry almost no load so so you're welcome to go a step or two larger on the tap drill to make the tapping go easier.  So in other words rather than using the typical #18 tap drill for a 50% thread, you can instead go with a #17.

[rsterne]

My first one was offset, like Jason's (upper assembly).... Then I built an SSG, with the mount moved forward (lower assembly)....



Final result.... Details in this thread, Reply #66.... https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.66



You may also want to look at some of the ideas for QB SSGs in these threads.... 

https://www.gatewaytoairguns.org/GTA/index.php?topic=102095.860

https://www.gatewaytoairguns.org/GTA/index.php?topic=164226.

Bob

[Gippeto]

Many moons back and on a different forum, a fellow from the UK named Al Stone posted an rva for a QB that retains the cock on close function. At the time, I did obtain some drawings from him and made one.

No longer use it, but it's still kind of a neat piece.



Al

[mackeral5]

Many moons back and on a different forum, a fellow from the UK named Al Stone posted an rva for a QB that retains the cock on close function. At the time, I did obtain some drawings from him and made one.

No longer use it, but it's still kind of a neat piece.



Al

That is indeed a very neat piece  thanks for sharing.