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Old October 24th, 2005, 02:50   #22
Delierious Designer of Dastardly Detonations
MadMax's Avatar
Join Date: Dec 2001
Location: in the dark recesses of some metal chip filled machine shop
Where did you read about the combustion system? I'd love to get more details on this marker. It would certainly explain how they surmounted the combustion issues. I couldn't beat my problem with a reasonably sized chamber. I had to go with bigass can about the same size in the PEP if I were to keep things at a starting pressure of 1atm. I can see how they could promise consistent performance with temperature if they went with combustion.

I would think that they would just go with direct drive using the direct exhaust instead of driving a piston. The thermal impulse would be pretty short so I don't think the pellet would be damaged. Clanging around a piston works fine with a nail driver because the speeds aren't that high, but with projectile speeds, you end up putting a lot of energy into moving heavy metal parts instead of the projectile. Not very efficient.

I have reservations threading a tank rigidly onto a gun like the PEP. I've ripped off the fittings off of empty propane tanks (intentionally to examine the valve design). I chuck a propane adaptor in my lathe and thread the tank on. I don't have to push too hard on the tank to yield the metal around the valve fitting. A couple flexings and I can rip the fitting right off. A bottle threaded onto a rigid rifle could have the fitting ripped if a player falls on their gun and bends at the root of the fitting. An entire bottle of propane venting in one go is a fair bit of propane.
Want nearly free GBB gas?

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