Crosman 22XX 88g AirSource Adapter--Part 1

Since I'm on a CO2 roll lately, its finally time to get to a piece I've contemplated for way too long now. I've been kicking the idea around for a way to add a small external CO2 tank to one of my Crosman 2240/50 guns. After seeing my buddy Joe's Hammerli 850 Air Magnum, I wondered if I could just use an 88 gram AirSource cartridge. Bruce (aka Mr B) from the Pyramyd Air blog was kind enough to send me some empty Crosman AirSource cartridges to take measurements. Unfortunately, the diameter of the AirSource cartridge prevents it fitting directly in-line with the 22XX valve. It just won't quite fit under the barrel. Essentially, I need an offset mount for the tank to the valve. And that's where the project more or less stalled out. I had a couple ideas, but lack of a suitable piece of raw material and an endless stream of other projects took precedence--until now. I looked at the QB tank block from Steve at Archer Airguns. In unmodified form, that tank block won't work in my particular application without extensive re-work--enough so that it made sense to just start from scratch but with that basic idea. The other issues that arose centered on whether to make a piercing mechanism for the A/S cartridges or make them refillable. Then there was the usual research to determine thread sizes, source pieces, raw materials and tooling...ahhh, you know.

Dave from Radial Grinding was kind enough to supply me with the needed 1.5" diameter brass. Anybody priced brass lately? I need to buy Dave lunch.

After lots of napkin sketches and dragging my feet even more, I decided that the piece was just a bit too long. At full width, this is one heavy piece of metal.

I parted off almost half an inch.

Title this one: Big cut for little lathe.

Crazy. And it worked just dandy. Advancing the cutting blade incrementally in the holder as I cut deeper kept the set-up as stiff as possible.

Faced both ends.

Still wanted (needed?) to take some weight out of the adapter, so I cut a flat.

Without moving the carriage from my final cut, I measured the width of the cut piece in the chuck. Subtracting that from 1.5"--the original diameter of the brass rod told me I'd removed 0.244"--and how much to remove from the opposite side to keep things even.

I touched the stop against the carriage and locked the carriage in place.

Loosened the stop then placed a stack of feeler gauges between the carriage and the stop. The stack of feeler gauges were equal to the 0.244".

Another view.

So the gap to the stop is the depth of the next cut.

Flipped the piece putting the new flat against the chuck.

Then, I just advanced the cut until the carriage bottomed out.

The sides are within just a couple thousandths. Good enough. Next, I did some layout finding the hole locations and depths for the A/S and the 22XX valve thread.

Big markings so I don't do anything (more) stupid (than usual).

After endless centering on the punch mark , I finally spotted the hole for the 9/16-18 valve threads.

Gradually drilled...

...then bored to 0.515"--my tapping size.

Without disturbing the set up in the chuck, I tapped the 9/16-18 thread.

Note the work piece's offset in the 4-jaw. Couldn't turn at anything but the very slowest speed otherwise the vibration got ugly. Could've used a steel or brass packing block to act as a counterbalance--that might have allowed faster turning speeds--but this worked. Just barely.

Threads cut

Still keeping the set-up intact, I bored the relief for an o-ring seat. Matched the original dimensions used by Crosman on the 22XX valve.

One down, one more hole (two actually) to go.

Here's the centering procedure I mentioned above. With a pointed center indicator in the tailstock, the work is adjusted in the 4-jaw and rotated by hand until the center punch has no perceptible run out under magnification.

I'm set up to start the A/S threading next time around.

Rochester Disassembly/Reassembly, Part 7

I decided it would be a good idea to test things out now that the valve and pump work.

Reassembled the breech with the pellet trough and barrel.

A thin o-ring.

In the valve body groove

Nope, not enough clearance. I could cut that groove deeper although I’m not sure whether that’s needed. The teflon tape alone seems to give a great seal between the tube and valve body.

Things you notice only after the fact when looking at pictures after the fact – a small piece of teflon tape hanging over the front of the valve inlet face. I won’t make that mistake again.

The parts screwed together and aligned perfectly (as witnessed by the old solder blob.)

I decided to use one of the hammer springs and locknuts from another Rochester as the one from this gun was short…

Have to assemble the bolt first, then the hammer…

The bent rear sight.

Placed loosely in a vise under the arbor press ram.

Bent…

Another thing I didn’t notice until I looked at the pictures – an old burr on the stamping. I’ll have to dress that.

In place. Does it go this way or backwards? I need to dig up some pictures.

The gun is now holding air well, and I spent a half hour plinking at cans. I still need to chrony it. There’s a bit too much headspace between the pump plunger and the valve face so that the residual air pressure causes the lever to flip open. So I have to address that as well as make a new pump cup.

Getting there!

CO2 Tank Adapter for the Aeron Part 2 Final

Back to the tank fill adapter for the Czech CO2 tanks that came with the Aeron guns.

Up top is the tank. I've attached the bulk-fill adapter that will be screwed to the gun. I need a better look at the tank/bulk-fill adapter interface. That'll reverse engineer the dimensions for my tank adapter.

Started by removing the o-ring that seals to the tank valve stem. It's size P8.

Then removed the large clip...

and pulled the body out. A small punch presses out the pin that retains the check valve.

Here's the entire bulk-fill cap from the Aeron pistol. I didn't remove the large o-ring on the body--that seals the end of the gas tube housed inside the gun's grip.

Measured the ID of the bulk-fill adapter with a telescoping hole gauge.

The hole gauge is spring loaded and expands inside the bore. It's then locked, removed and measured across the ends. 0.353" on the micrometer.

Used a depth micrometer to measure from the face to shoulder on the counterbore. It's not a true flat-bottomed hole, but it'll get me in the ballpark. 0.334" Since the valve stem on the tank is sealed around it's circumference, there's some leeway here. Ideally, the bottom of the counterbore will crack the tank's pin valve open for filling.

Spotted.

Drilled to a depth of 0.330" to the shoulder of the bit with an 11/32" drill bit.

Then opened up the hole to 0.353" with a small boring bar.

Ground one end of a lathe knife to sort of an L-shape to cut the internal groove for the o-ring.

Took a bit of trial and error with the tool before I had the relief clearances and rake correct, but it worked. Repeatedly test fit the o-ring several times until it fit correctly and the tank seated--and sealed.

Then through drilled.

Turned the adapter around and started the taper on the end of the M16 A/S thread with a shaped knife. All the taper does is interface with the deep internal o-ring on female A/S fittings.

Wasn't getting quite what I was after, so I switched to the Taig Radius Turning tool.

Don't ask about the clearances. I took very light cuts for control and was extremely mindful of where the 3-jaw and the tool were at all times.

top view.

Done?

Ahhh, the missing link.

So, this gets more or less permanently attached to a Crosman A/S to paintball adapter.

and I'm in business.

If you're starting from zero and need to fill a Czech tank like this from a paintball tank, there are probably easier ways to go about it. This kludge was my "minimal machining solution" (trade mark pending) based on utilizing fittings I already had on hand from my other CO2 guns.

Once the tank is charged, the B&A valve connector is closed at the paintball tank end, then the Aeron tank is unscrewed from the steel fitting. It gives just a quick pop of gas--no prolonged hiss to empty the tank. Couldn't have asked for a better result.

To charge the gun from the tank, I shot the gun empty and removed the 12 gram end cap.

Side note on the Aeron 12 gram cap: The 12 gram cap normally has a dull piercing pin that will just give you trouble. A couple seconds on the bench grinder gives it a triangular, reinforced chisel point. Avoid the temptation to make it a needle or cone shape. This is stronger.

Screwed on the bulk fill cap.

And attached the gassed up tank.

Almost forgot, the gun must be cocked first.

Ready to rip for pennies per charge.