Russian_Kangaroo wrote: That is actually a pretty nifty design that i have seen while roaming the forums but i dont think i would be able to scale to the gun i want to make. I was hoping to build a rifle - esque pneumatic that fired 50 cal round.
I got the idea from here
, (I was "fullmetaljacket" back then), the pictures are dead not but Spudinator was using 12 gauge slugs of the type shaped like airgun pellets (like these
- shuttlecock shaped, or shuttle[male reproductive organs]
according to spudtech
) in a 0.75" barrel and was getting good semi-auto feeding.
Do your rounds fire quite strong at 100 psi seeing as there would, im guessing, be a level of leaniance in the barrel to allow for the pellets to be able to fall into the the barrel in the correct position or do the angled tails really remove most of this needed room. Im sure that design could be made in a semi automatic fashion but the the round that i wish to use neesd to be able to recieve the best fit possible.
At 100 psi as you can see from the video my design was putting 0.22" pellets through 0.5mm aluminium pretty easily, if you scale up the calibre for the same pressure (and valve efficiency) you will get a lot more force, eg going from 0.25" to 0.50" you will get 4 times the force. For smaller calibres, higher pressure is a better idea.
Secondly one question i need to know for that gun is how you attached the hopper?
Does the pressure have a huge effect seeing as the compressed air is trying to escape and so will take any path or does the compressed air pass the closed area of the barrel that makes of the area where ammuntion comes from, having negigible effects on the ammuntion feeding area?
Naturally as the air expands into the hopper it will lose pressure and therefore give you less power, but for a small sealed hopper it won't make a huge difference. You can also negate this by including some form of blow-forward bolt
that seals off the magazine on firing.