Inspiration to do this is from a couple of very clever people that have given me good advise and the recent purchase of a small vertical mill has rocketed my confidence in build quality.

This won't be a long thread, but you should get the general idea of what i've done.

I started looking at other designs in both the big bore and lower power design. The possibilities and concepts rattled around my brain for a while and I started off planning to use the std valve system that came in the 22XX.  I ended up using a bigger sized tube, and so I had to make my own valve and hammer system.

My main concern in all of this was safety. So after getting all the info together I felt good about what I was to do with a 3  x safety factor for retaining the pressure. With this sorted it gave me a base to work off.

I didn't know what sort of performance the pistol would produce, but I have been pleasantly surprised and now have a base to work off for future build and refinements.

Photos show a few different stages including my trial and error parts. I basically built the pistol twice. This was a good idea as it meant the finished item had minimal adjustments made to it, and my measurements are recorded, so each build will be quicker.

Photo to come in another post. Thought i'd get the words done and dusted first. I will also share a bit more detail about it's performance too.

Pretty bloody cool..

I used JSB 18.13 grn pellets.

33 usable shots and quite a gentle power curve. The variation between shots jumped about, but as I was shooting this string I was shooting groups and on paper it was a dead rabbit every shot.

Hopefully in the future I can refine this with trialing different spring tension and addition of a hammer tension adjuster to balance the valve and hammer. Shot string copied below.

I'm not after perfection, and to me it's a victory so far enjoying shooting it. I have teamed this up with a cheap hand pump and it only takes 50 strokes to fill to around 1800 psi according to the gauge on the pump. It's turning out to be a good little combo.

That should flatten out your power curve nicely, maybe even give you a few more shots.

Yes, it's a possibility for sure. On another build I can make the tank bigger so that there's more room for a reg and air. It will probably suit a carbine style gun with the bigger tank, as it will be kinda big for a pistol, although Dirty Harry had no problem wielding his pistol.

Whats the barrel length and over all length?

And how do you fill the tank?

A Punga, thats a good one. I do have designs here somewhere i found online a couple of years ago. I will see if i can dig them up and go over them to see if there is anything interesting

First string using 15.89 grn JSB with the hammer adjuster wound in 2 turns

Next Using 18.13 grn JSB hammer on same setting

then 18.13 grn JSB with hammer wound in 4 turns

So what I see is that the heavier pellets get better power out of the gun. There's no benefit filling it to a higher pressure with this valve/hammer set up, and that I think maybe 1 to 1.5 turns will be a good setting putting out around 13 fpe for more amount of usable shots.

At 4 turns it was shooting around 17 fpe for the first 5 shots, which is good power I reckon, but just not the air capacity for many shots.

Overall I am really pleased with how it's turned out, as it is good enough as a hunter if you can stalk and shoot a pistol well.

its looking great with the wood grips on! 

Performing nicely too

The next build will get them, but here they are with a first coat of oil.

This time I am using a cap head screw for the hammer pin with a bushing to stop threads catching on the slot. Certainly feels more solid than a pin. 

I still need to make a pellet tray and figure out the best way to attach the breech to the main tube, but everything fits together really well and the cocking is really positive and feels great using cap screws instead of a pin. 

I have figured out I need to make the actual hammer longer so the screw is further back, as how it is now, the probe won't travel back enough to load the pellet. the extra size of the cap heads cause this.  All in the name of product development.

I am planning on this being a straight pull bolt with a lockup mechanism. If I was making a revolving bolt that you lift and pull, I would need a meatier breech so that 90 deg channels could be cut into it to lock up probe for firing.

I used a 32mm round wood routing bit to form the bottom of the breech to fit the main tube. 

The stainless is really good to work with and my tooling seems to handle it well. The hollow probe comes out really well and I seem to be able to make them quite easily now, especially with the mill. I use the end mill to form the hollow part by plunging down and this comes out nicely with just a little bit of filing required. The mill also ensures a proper 90 threaded hole in the probe for bolts, and in this case a cap screw for the cocking lug.

 Be dam handy thing to know, if you start with mags as well. 

 Sweet work Pauly, gonna be fun watching you devolp and fine tune the pistol. 

 Got a name brewing for it? 

 Would work. 

what pressure do you plan to fill the cylinder to?

Im looking forward to seeing some groups 

 Like the breech on second. What's the size difference compared to original. 

 10 ft. Lb is a good amount of power for a bird gun. Fancy chucking a stock on one and testing it out to 30m? Be keen to see its accuracy when it streaches out a bit. 

 Whats the end goal? Hunting pistol, target pistols?

 Decided on a finish for them or you they stay metal? 

I don't plan to change colour, but have wondered what home anodising would look like, but quite like that semi polished alu with black or walnut look. Giving them a polish seems to harden the surface a bit too and they don't mark as much as unpolished.

They are both the same tank size and calibre. Latest has a shorter barrel.

Yea, I will try the stock on them, as I am keen to see what they go like at longer distances too. I will put a rifle scope on also as the pistol scope is challenging to use.

 Just throwing random ideas. Pistols are great as is, but you know arm chair spectator and all that. 👍

Blueing sounds good, but don't think alu responds to that.

I am coming up with a trigger frame made out of alu plate, or even a block including trigger frame that the air tube attaches too.

Ideas are great, it's surprising that although some seem ambitious, there are concepts and ideas to be taken from them.

Sweet pair! 

now... how about spring loaded bolt so you pull back and lock open to load it then a button releases the bolt forward ready to fire??

 Noisier than just closing it? 

 Run the risk of wedging the pellet if it didn't sit straight.

 

 I know with the 1322 I like charged, then decocking the bolt slowly, pushing the pellet in with bolt, then leaving the bolt loose ( sitting in firing position, not locked but saftey on) which allows me to keep the hammer spring from sitting under tension as I wait or stalk.

 Extend probe (Pauly made) needs to be cocked to allow the pellet to fit, so no chance of pellet falling out if not cocked. Plus the probe pushes it in far enough it doesn't come loose. 

 Cocking is just pull back, push forward, turn downwards in one short, quick, hardly noticable finger movement.

 But that's just my view. Could be a good set up for all I know never having tried a button release bolt. 

 Think those brown pistol grips toned it down a alot more.

 Still looks good. If it preforms as as well as it looks, that's easily gonna be a 30m bird gun.

 Whats the balance like with stock on? 

I like the idea of making a walnut forestock along the tank to give it a touch of height. I don't mind the black and metal, but a nice walnut is my preference. weather too bad here to go anywhere this week end.

It really needs a cheek riser as my chin is all that touches as the scope is so high, but I gave it a go anyway.

It's actually great to use like this, and it was an enjoyable little shoot.

I put 2 targets out at 20 and 32 m. You can see the orange squares on the pellets in the photo. I was shooting off my raised knee sitting in my ute, out the window, so not a totally stable position. There was a brisk blustery wind coming at me, so you can see the pellets hitting slightly left.

The groups look kinda bad, but you can see a couple of good clusters there that happened once I settled in a bit. I am quite happy with this, as I know that with a proper shooting position and improved cheek support, that this is quite an accurate little gun, and 30 m is a huntable range.

After thinking about hunting pistols a lot lately, I feel that for hunting, having something with a bit of length is good, as I would tend to support it against something like sticks, or a tree rather than freehand, so this is easier to do with a longer pistol.

Or they have hit old pellets already embedded in that bit of wood, as i've used it before to put targets on.

If you look back through this thread I have groups at 15m that are shot with 18 grn. I have tried rws and 15 grn JSB and the 18 grn JSB seem the best and yeild the best power from the pistol. I don't sort my pellets, but check the skirts as I take them from the tin.

Pretty sure those groups can be tightened with a better shooting position.