QB78/9 and Gauntlet K.I.S.S. SSG

[mackeral5]

I had a couple of these on my bench, decided to take a pic and repost.  It has been a few years since sharing this simple design.

It uses a Crosman 22xx end cap and requires you to convert rear breech retention to the crosman design.  Drill/countersink a hole in the breech and convert to 2 8/32 fasteners. 

One design doesn't protrude out the back, preload and gap are set during assembly.  The other design includes an adjustment knob that protrudes out the back and allows for preload adjustment.  Gap is fixed in this design. 

All of these components are readily available via Mcmaster Car, Amazon, etc..  The most precise steps are drilling the hole in the end cap and adding the upper breech screw hole to the breech.  Everything else is hacksaw/file work.....

I use one of these on all of my QB78 builds and my .25 Gauntlet.

[MittensKitten]

Could you explain what that part is and how you've improved it? Also,  when drilling small metal  parts like that, how do you find the center of the circle or in other instances an exact point on a component. Is this sort of thing done on a drill press with the piece clamped down or on a cnc machine? I'm new to modifying airguns and just bought a QB79 to learn with. Thanks for any info.

[Rohmpm]

I am curious as to your Gauntlet build and did it help you shot count/power. I built an additional plenum and a TSS for mine but am just starting tests.

[mackeral5]

Finding center....use various pieces as a centering jig... You have to get creative.   Making mistakes is part of the learning process.  All of my builds involve cordless drills , a dremel, a portaband, and that's about it. 

Read the sticky at the top of the page concerning SSG's.  Their primary duty is to conserve air by reducing hammer bounce.   My Gauntlet build is documented in a post from a year or two ago.  It follows the same path as many others, mostly items learned in tuning my QB78's.  Increase porting to 75-80% of bore size.  Match ports between parts. Smooth/round the inside corner of any turns in the airflow.  Go to a harder poppet.  Use some method to Control hammer bounce---SSG, SSS, etc.  Decide what your goals are and set the reg to match....then tune/tweak the preload or gap depending on what you are using for a hammer spring system...

[MittensKitten]

Thanks for the guidance!

[mackeral5]

Thanks for the guidance!

You're welcome.  There's a ton of QB info available using the search function.  Unfortunately allot of pics are no longer available due to pic hosting companies shutting down, changing policy, etc. 

It's a fun platform to learn with, but be careful cost-wise because now you can easily end up with a QB that costs more than a more modern gun with more features, such as the Benjamin Fortitude, or even the QB's offspring, the Gauntlet.

I have a handful of QB variants that I'll never get rid of. 

[YEMX]

That hidden version is trick!!  I like it!!

[mackeral5]

That hidden version is trick!!  I like it!!

Thanks Tom
 
There was a time where I thought having that knob hanging out the back was the coolest thing.  As of late,  I find it very useful for tuning and develpment,.but once I find my tune I convert to the hidden/fixed version.

It is also very easy to go to twin springs.  My qb .357 runs one of these with twin springs...