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A 50 pound crossbow pistol to fire a ball valve.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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A 50 pound crossbow pistol to fire a ball valve.

Unread postAuthor: boyntonstu » Tue May 11, 2010 6:20 pm

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A 50 pound crossbow pistol to fire a ball valve.

Works OK but it needs some tuning.

The oxygen bottle and a gauge plus ball valves at the end of the feed hose allows me to fill the chamber to any pressure less than max.

I can get at least 10 shots per fill.

I plan to use the same barrel that fits the Trom-Boyn for comparison shots.
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Unread postAuthor: Gun Freak » Tue May 11, 2010 6:25 pm

Wow that's pretty nice, must be pretty comfortable to shoot, eh?
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Unread postAuthor: JDP12 » Tue May 11, 2010 6:28 pm

As an avid archer id say what youre doing is tantamount to dry firing it. No bow is meant to be dryfired, an even though some force is being transferred, i dont think enough. Id be extremely careful if i were you
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Unread postAuthor: Marffy » Tue May 11, 2010 6:29 pm

Would you say it was worth tearing apart a cross-bow pistol? looks pretty good though.
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Unread postAuthor: boyntonstu » Tue May 11, 2010 6:33 pm

Gun Freak wrote:Wow that's pretty nice, must be pretty comfortable to shoot, eh?


Thanks.

It is a prototype for testing.

However a few points:

I am a righty yet it feels good pulling the trigger with my left hand.

Most rifles and shotguns have 14" between the butt and the trigger.

The end of the plywood that points down at the chamber end is 14".


Instead, I would fire it lefty, add a right hand grip at 14" and have the chamber rest over my shoulder.

Similar to a Thompson sub-machine-gun.
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Unread postAuthor: boyntonstu » Tue May 11, 2010 6:38 pm

Marffy wrote:Would you say it was worth tearing apart a cross-bow pistol? looks pretty good though.


Can you make a spring, pistol grip, and a safety for $15?

That's what they sell for on ebay.

http://cgi.ebay.com/NEW-Hunting-Archery-50-LB-PISTOL-CROSSBOW-Gun-w-Arrows-/150442895180?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item230718674c

BTW I didn't tear anything apart. It goes back together, but I wouldn't want to do it.

It fired an 80 gr bolt at 164 fps with terrible accuracy.
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Last edited by boyntonstu on Tue May 11, 2010 6:49 pm, edited 1 time in total.
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Unread postAuthor: boyntonstu » Tue May 11, 2010 6:40 pm

JDP12 wrote:As an avid archer id say what youre doing is tantamount to dry firing it. No bow is meant to be dryfired, an even though some force is being transferred, i dont think enough. Id be extremely careful if i were you


I disagree.

Dry firing a crossbow is a no load situation.

Pulling a 3/4" ball valve open is further away from dry firing than shooting a bolt.
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Unread postAuthor: JDP12 » Tue May 11, 2010 6:46 pm

Yes i know. Thus all the energy from firing gets transferred into the limbs of the bow instead of something else, normally an arrow/bolt. Ive seen limbs literally explode because theyre not meant to handle all of that energy. I dont know how much force the valve takes o open, but i doubt its a ton.

Also please edit your posts instead of triple posting.
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Unread postAuthor: boyntonstu » Tue May 11, 2010 7:10 pm

JDP12 wrote:Yes i know. Thus all the energy from firing gets transferred into the limbs of the bow instead of something else, normally an arrow/bolt. Ive seen limbs literally explode because theyre not meant to handle all of that energy. I dont know how much force the valve takes o open, but i doubt its a ton.

Also please edit your posts instead of triple posting.


The limbs are steel (1 piece). Did you ever see 50 pound steel limbs explode?
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Unread postAuthor: JDP12 » Tue May 11, 2010 7:19 pm

Ah. Well i didnt know they were steel. Thpught they were jst traditional laminated wood. Sorry
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Unread postAuthor: Marffy » Tue May 11, 2010 8:29 pm

boyntonstu wrote:Can you make a spring, pistol grip, and a safety for $15?

That's what they sell for on ebay.



wow, thats cheap. dint know. I'd definitely try this for that price.
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