Pneumatic Skewer Gun / Rifle. Not Pvc,

A pneumatic skewer rifle made from left over plumbing parts from the shed.
Fires reasonably well, only tested at around 100 P.S.I fairly self explanatory construction,all measurments were purely guess work, and although ive included a few images for scale later minor adjustments were made, please leave any questions as comments.
parts;
length of 15mm copper pipe (around 6ft), 4x compression fitting corner pieces, 3x isolating valves, 1 of which is a tap type the other 2 screw driver operated (although all tap would be preferable), 1 solder banded end cap, bolt in car tire valve, ptfe tape, epoxy resin and
6mm (4mm inner diameter) aluminium pipe.
To pump up: open first valve (nearest tire valve) and second leaving final closed, pump up (not tested past 100 P.S.I), close first and second valve, drop skewer down barrel, to fire release third valve, to reload close third valve and open second.
I accept no responsibility for damage done to property or self as a result of making or attempting to use this.
first instructable (well slideshow) so be constructive. sorry about poor photograph quality.I'll add a video when i can, if requested.