Build log for 1st High Pressure Pneumatic

[Novacastrian]

I love combustions, but i wanted more power from a small chamber firing 12.7mm rounds.
I knew a pneumatic could do this under normal pressure, but with a large chamber. I asked a fellow member his expert opinion and he promptly sent me his idea for a 300 psi small chamber High Velocity Spud Accelerator.
I will post pics as i continue construction, here are a few to start with, the chamber with lfx sleeve, and the lfx piston with polyurethane integral sealing face.



I can't thank Jacksmirkingrevenge enough, and as he is as true Gentleman he gets full credit for this project, Thanks Jack

[jackssmirkingrevenge]

I'm very impressed so far

In all fairness all I provided was a basic drawing:



The interpretation of the drawing and choice of construction is all down to the builder - and that makes the difference. There are tons of good ideas out there, but if you don´t have the facilities to flesh them out, it's all they'll ever be.

kudos, keep it up

[wannabie]

looks good so far lol

what type of pipe are you using?

[Novacastrian]

Pvc rod, machined to my specs I also use an internal sleeve of L.F.X. ,a self lubricating polymer.

[Novacastrian]

I have just changed the piston to glass filled ptfe, the lfx one was too tight a fit, i also used softer polyurethane, so it seals better. pics soon....

Edit, i forgot to mention that the end cap with integral bumper is also complete, well iv'e gotta drill a hole out to place the schrader.
The poly is 55 duro, very good for this purpose. oh yeah and the whole gun will *weigh 600grm approx, the piston weighs 14 grams

Edit edit, that *weight includes the silencer

Weigh is not a word

[jackssmirkingrevenge]

Still keen to see the finished result

[Novacastrian]

Not long now Jack.....

[jackssmirkingrevenge]

Might I make one small suggestion for the silencer, if you're using multiple chambers I think a series of holes will work better than the slits you cut into the barrel of your 12.7mm combustion.

[chaos]

Might I make one small suggestion for the silencer, if you're using multiple chambers I think a series of holes will work better than the slits you cut into the barrel of your 12.7mm combustion.

ill agree with jack here i have tried both slits and holes with baffles and the one with holes seemed to work a lot better.

[wannabie]

Sounds better by the post I cant wait to see it, I wonder what kind of speeds you will get...

oh yeah there only seems to be 4 people posting on the thread... thats odd

[Novacastrian]

Odd or not i will use your suggestion for the holes. i have the other barrel and it seems to port very quickly, it reduces db by approx 40 percent max.
Thanx for all the support...x4

Edit: it sounds kinda stoopid but with the holes, would it change the frequency of sound disgharged by your gun, they could be tunable

[jackssmirkingrevenge]

Also for maximum effectiveness, why not have the silencer outer case shroud the whole length of barrel?

[MrCrowley]

On the subject of silencers, (note I don't helluva lot about the maximum effectiveness of them) couldn't you have a very effective silencer by doing what jack said, having the shroud the whole length of the barrel, and then what if you have a longer barrel then what you would have originally.

The wasted air wont shouldn't have too much effect on the velocity, so it would also be quieter and more effiecent then if you had a short barrel?

[Novacastrian]

Jack, my dear friend, you have, have you not heard the story of the german
.22 calibre rimfire that is SILENT apart from the click.. i think you may have provided the link, YOU ROCK, i really like the idea, i will start brainstorming.
I would really like your help with ideas as i would other members

[Novacastrian]

I'm designing a new "Flat Top" Silencer, it will be fat on the bottom and WILL require a pod, however it will allow aiming by eye, over the top of the barrel.
It will kind of look like a cam, with the barrel as the shaft.