Barrels

[warhead052]

Well, if its two cylinders going into each other, you would have to rotate it until it works, if its built in and pre drilled, well no need to line it up.

[Goats spudz]

no you wouldn't you have a 15mm tube and a 15mm barrel both with the same ID of 4.5 or 5.5 mm depending on caliber, going into a 15.01 mm hole it will line up

[DYI]

Goats, I think what warhead is getting at is the issue of concentricity of the bore with the tube for both tubes.

So long as the barrel's bore is sufficiently concentric with its external diameter, this is just a matter of producing the OD and ID of the other part without re-chucking, which will ensure concentricity.

[Gippeto]

Keep it simple...drill the transfer port into the barrel...or use a longish flow through bolt. This really does not have to be difficult.

[wyz2285]

Flow through bolt
That solves everything But how does it affects the flow? I still want a muzzle speed of >1000 fps

[Gippeto]

I still want a muzzle speed of >1000 fps

Not for accuracy you don't. Max should be around 900fps with whatever ends up grouping best....hopefully 10.3gr. Best accuracy will likely be slower yet.

[wyz2285]

But won´t higher speed give a straighter trajectory? Accuracy for me comes first, but I do hope it can do some damage like penetrate a coke can at 40/50 meters

[DYI]

At speeds where trans-sonic effects become noticeable, accuracy will be reduced. If you want "damage", you shouldn't be firing .177 pellets with compressed air

[wyz2285]

you shouldn't be firing .177 pellets with compressed air

I did took a long thought about machine about 5 cartridge and make bolt-action hybrid, but from JSR´s results, valveless isn´t reliable, burst-disc is too complicate. But indeed, I should use this opportunity to build a decent hybrid (but hybrid is that kind of thing that´s between firearm and hobby also because spudding isn´t popular around here at all, I can´t even find a law about it)

[DYI]

Come on wyz, you should have at least included an ellipsis at the start of that quote

I don't have any problem with traditional pellet guns, and a hybrid gun which fills the function you're looking to achieve would be very difficult to design, and quite expensive. It's also worth noting that the pellets you want to fire are not designed for stable supersonic flight, and that the launch forces may end up destroying them, especially in a commercial barrel which has a twist rate appropriate for operation as a compressed air pneumatic.

[Goats spudz]

IIRC the airforce condor reaches 1200+ FPS with room temperature air

[wyz2285]

you shouldn't be firing with compressed air

True true, but time will tell, if there are any time left to design a above 50x hybrid, I´d give it a go, as have the parts machined won´t cost me a penny the only problem would be where to shot it.
Gippeto: What do you think about this?

[Gippeto]

IIRC the airforce condor reaches 1200+ FPS with room temperature air

Yep, the Condor can reach those speeds...and more. I've seen a much modified Condor shooting .177's chronying ~1400fps and still grouping "fair" at 25m. Was ~ 3/8" ctc as I recall. Would be real deadly close up.

But push the range out....and it becomes a truly ineffective shotgun.

The owner switched to a .25 setup to make better use of the air he was using...now pesting beyond 100m.

If trajectory is your biggest issue, get chairgun. When you've settled on a pellet and velocity, you enter that data into chairgun and print yourself a handy trajectory chart...if yer real picky, get a range finder to add to your kit.

Edit: You REALLY don't want to drill that hole do ya. You really won't bugger the whole barrel if you fork up the tp hole once or twice....at worst it costs you an inch or so of length....and you won't fork it up.

That's the basic idea. The hollow section of the probe should be ~.010" smaller than the lands of the rifling...this will allow you to NOT have to chamber the barrel. (assuming you don't drill the barrel for the tp)

Obviously the barrel cannot be allowed to block the flow to the probe...the receiver block is going to need some alteration to accommodate the transfer port and the probe will need to be lengthened to compensate.

ORRRRR...you could drill the bloody hole in the barrel.

[wyz2285]

Fine!, I drill the hole should be fine.
Also, once this gun is finished, and I feel more experienced, I would design a .22 with high muzzle speed, for now looks like I should stay around 900 fps, witch it´s good too, it will give me more shots, also much easier to open with a solenoid

[wyz2285]

Watched this video.
Is the bad accuracy because it was too powerful or there are something to do with the barrel I saw a edgun matador shooting pretty well at 100 yards with a L.W barrel