9mm 22xx running on a hipac can be done...do not expect it to be cheap. You might find a DAQ 9mm upper (receiver, bolt and barrel) for a few hundred...if you're lucky...I believe they are no longer in production.
Performance with a bore that large would be better if you secured the valve and bulked the tube rather than used the Hipac ... due to potential for increased volume available at the valve face. You have to actually utilize that potential of course.
More $$$
Unless....you can do it yourself.
.308" rifle based (somewhat ) on a QB78.
.310" pistol based (somewhat ) on a 22xx.
"It could be that the purpose of your life is to serve as a warning to others" – unknown
Liberalism is a mental disorder, reality is it's cure.
I bet both of them pack a serious punch. I was thinking of building something like a 9mm with a Lothar Walther barrel (28'' for $178 I think..) , a big old' 1 inch brass coaxial valve with a co2 12g adapter until I move up to HPA.
Or a hammer valve of sorts, with a good sized amount of flow. I don't have any machining equipment and custom parts like a receiver and a hammer w/ trigger is a boat load of money, and takes the fun out of the build, IMHO. 8)
For now, ideas.... along with a .22 full auto hammer valve blow back gun, similar to the all mighty Caselman, a 9mm bore Hybrid with onboard metering propane.
I'm working on a coaxial slide valve combo, with a 6.03mm tight bore and a hop-up for airsoft sniping.
Its good to keep the mind busy
EDIT: Lets see a pistol grip on that "rifle based" QB78...
You could also contact Mike at TJ's Enterprises for a barrel....will likely cost you less than the LW, but will require you to do some bore polishing to get the best accuracy. Can also get greater lengths than from LW....Mike does charge a premium for 30"+ but it's still affordable.
Price is by the inch and I don't have my price sheet handy.
How good can these barrels be when everything is in harmony?
Google will provide a phone number for TJ's.
Trigger groups for Crosman or QB products run around the $30 mark....hardly a boat load.
Edit: Thinking thumbhole stock for the QB...black walnut or zebra wood...haven't decided yet.
"It could be that the purpose of your life is to serve as a warning to others" – unknown
Liberalism is a mental disorder, reality is it's cure.
Amongst many other things, I will be printing some discarding sabot's (The front portion, the pusher plate will be a harder material of course haha) to hopefully put this guy down range some day sooner then never!
Something that I've been playing it over the past couple of days, converting a Milsig K-series paintball marker to take RAP4 DMAG 20 round magazines, worked out pretty well.
[youtube][/youtube]
some photos of the mods done:
On the marker body itself, lower rails next to the paintball port milled off to allow the DMAG to enter the magwell enough to click against the catch.
Bottom view of modified magwell showing white delrin spacer and tab to open feed lip
Top view of modified magwell showing area milled out to allow mag entry
External view of feed lip tab bolted on.
Magazine follower modification (modified follower on the left) showing steel pin to limit travel
Comparison of modified magazine on the right and unmodified magazine on the left showing travel limit in order to stop the last ball being chopped by the bolt.
hectmarr wrote:You have to make many weapons, because this field is long and short life
I decided I really wanted to blow something up today.
So, I took some scrap 1.5mm steel (from some computer cases I recently threw out) and cut it up so I could bolt four layers of the stuff together:
I know it's not that impressive a target - it's only mild steel and it'd be a lot stronger if it weren't in layers, but I'd guess it's probably still capable of catching many pistol rounds.
The full arrangement was as follows, with some water jugs behind and some concrete as a final backstop:
And, of course, there's a video:
[youtube][/youtube]
And so, one hole through some steel plates:
And some holes through the water jugs too:
Watched closely, the video shows the penetrator bounce off the rear backstop, bounce again off the concrete to the left side pieces, then again off the water jugs before landing in the grass. With that in mind, I'm fairly sure it would have had the energy left to go through more water jugs if I had more spare - I don't know how many though, as it was starting to turn sideways in the third jug. (However, treating water as an injury analogue, a three inch long penetrator going sideways would certainly have some interesting effects.)
A marginally modified version of this design that I've shown before.
The primary difference was angled fin edges and a rounded base to the penetrator - which was mostly to see if it was easier to make fins for that design (turns out it is, as I can just drill a hole in the plastic sheet, rather than faffing around trying to cut square holes).
Basically, if you take the long range darts I was trying to design years ago, this is a baby version that I'm using to experiment with the overall design; It's tamed down by using masonry nails as the penetrator - they're (mostly) ready shaped and hardened, which saves on experimentation effort, but it does reduce the diameter to 3.5mm rather than the full-fat 6mm (although the sectional density and velocity have been kept the same for testing).
The original had the fins slot into the penetrator (rather than vice versa) which was good for aerodynamics, as the fins didn't need to take the forces of passing several thousand Gs of acceleration to the penetrator and could therefore be thinner to reduce cross section.
However, it's more effort to make it that way and the returns of a small decrease in drag (as most of the drag on these is actually friction based, not pressure based) are irrelevant at the distances I can actually use this at. So I'm redesigning a bit.
Old but rust and dent free fire extinguisher tank was welded (by my welder) to a 200mm long 1" pipe nipple, and has an Y-piston valve, followed with 3" barrel.
Just a mockup for a pic, the valve will be switched around to work as a chamber sealing one, and needs a separate fill for pilot/airchamber.. Will work pretty much like a piston hybrid, but this valve has some serious flow...
You might find a DAQ 9mm upper (receiver, bolt and barrel) for a few hundred...if you're lucky...I believe they are no longer in production. 
