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 Post subject: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:15 pm 
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A guy on one of the other Forums converted a Crosman 2200 to HPA.... He did the math on the valve, but apparently didn't think about the strength of the bolt and receiver....

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The lower parts were a new flow-through bolt, which he blew up at 260 bar = 3800 psi.... He then (believe it or not) tried again with a stock bolt (upper parts).... with the same results.... Some parts were never recovered.... He didn't mention being injured, so I assume he wasn't....

What amazes me is that he tried it a second time.... The rearward force on the bolt was about 144 lbs, taken by the thin (pot metal?) receiver....

Bob

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:38 pm 
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rsterne wrote:
260 bar = 3800 psi.... The rearward force on the bolt was about 144 lbs, taken by the thin (pot metal?) receiver....

Bob


I don't think Crosman makes a gun for pressures that high. If the 2200 is the gun I think it is, there are far better platforms to work from at far lower pressures. 3.8 K psi on a piece of Chinese pot metal like that is really asking for it... That's the obvious point there.

What escapes me about this is the why. A little on-line research would have shown safety parameters.

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Doc Sharptail

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:38 pm 
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Darwin award winner there!

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:41 pm 
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Doc Sharptail wrote:
rsterne wrote:
260 bar = 3800 psi.... The rearward force on the bolt was about 144 lbs, taken by the thin (pot metal?) receiver....

Bob


I don't think Crosman makes a gun for pressures that high. If the 2200 is the gun I think it is, there are far better platforms to work from at far lower pressures. 3.8 K psi on a piece of Chinese pot metal like that is really asking for it... That's the obvious point there.

What escapes me about this is the why. A little on-line research would have shown safety parameters.

Regards,

Doc Sharptail


So American made pot metal would be better somehow?
The steady slamming of Chinese manufacturing all the while using quality made in China computing equipment drives me batty!

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:52 pm 
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Voltar1 wrote:
So American made pot metal would be better somehow?
The steady slamming of Chinese manufacturing all the while using quality made in China computing equipment drives me batty!


Suffer, pal :lol: :wink: . Everything is outsourced to China.
I think the last American pot metal I had in my hands was a Mk 1 frame, and that would not have stood up either... not to that kind of pressure.

Go batty :mrgreen: . I needed a good laugh this morning, thanks.

Yes, they are capable of mfg good things~ when the desire is there.

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Doc Sharptail

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 12:57 pm 
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Darwin candidate and certainly one with a horseshoe hidden somewhere.... and a change of underwear I bet.

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 1:04 pm 
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Plinkercases wrote:
Darwin candidate and certainly one with a horseshoe hidden somewhere.... and a change of underwear I bet.


Make that two underwear changes. That 2nd attempt really escapes me...

Regards,

Doc Sharptail

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 1:05 pm 
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:shock:

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 1:21 pm 
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why someone would want to HPA a 2200 at that pressure is beyond me :shock:
I can understand converting it to CO2 or HPA paintball tank @ 850psi which is more then enough to propel the pellet to a decent distance
but 3800 psi what was this guy thinking :axe:

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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 3:13 pm 
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The last thing that I am surprised by these days is how stupid people are.


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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 9:10 pm 
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I've never seen a complete 2200 (which is a pumper, in this case converted to PCP).... but I don't think that pot metal receiver is exposed to the air pressure, is it?.... As I understand it, that failure was caused just by the rearward force exerted on the bolt by the pressure inside the barrel.... I have used a valve from a 2200, and they look like a shorter version of the one in a 13XX, and I know that the 2200 tube is 3/4" OD x 0.065" wall steel tubing, I've used that also (on my Uber-Pumpers).... If the valve is properly retained in the tube, even in mild steel (44K yield, 53K tensile), that assembly should be good for 3000 psi with a 3.1:1 safety margin to yield, and 2.9:1 to burst at 3800 psi.... My point was that even if the tube and valve, the part that contains the pressure, WAS properly engineered for 3800 psi.... forgetting the force on the bolt (or other components) can be catastrophic.... Doing it twice just makes me shake my head.... :shock:

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 11:19 pm 
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So where is KG hanging out these days? :)

Okay...that was maybe a little mean, but struck me as funny at the moment...have a link Bob?

Al


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 Post subject: Re: Dangers of HPA
PostPosted: Tue Apr 07, 2015 11:24 pm 
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Gippeto wrote:
So where is KG hanging out these days? :)

Okay...that was maybe a little mean, but struck me as funny at the moment...have a link Bob?

Al


Quote:
Last visited: Thu Mar 13, 2014 7:10 pm


:wink:


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 Post subject: Re: Dangers of HPA
PostPosted: Wed Apr 08, 2015 6:08 am 
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rsterne wrote:
I've never seen a complete 2200 (which is a pumper, in this case converted to PCP).... but I don't think that pot metal receiver is exposed to the air pressure, is it?.... As I understand it, that failure was caused just by the rearward force exerted on the bolt by the pressure inside the barrel....


Yes, it's been kind of bothering me that I can't quite understand the failure mode here. I don't know how the bolt is held in place in those guns - I guess the answer is not particularly well! Is the bolt attached to some sort of sled that gets broken? Plastic perhaps?

Jim

Edit: Just pondering the strength of hammer spring you'd need to open the valve at 3800 psi, and where the cocking lever is attached. Perhaps the force of cocking did most of the damage?


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 Post subject: Re: Dangers of HPA
PostPosted: Wed Apr 08, 2015 10:26 am 
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from taking another look at that bolt assembly again it looks like he may have done some modifications Bob :?
I've never seen them with a steel bolt like that.. maybe he weakened it some...not sure :?
either way It still could not handle that pressure..

you can see the bolt in this pic its a plastic slide type....
2100 and 2200 are the same, the bolt is definitely not made for those kind of pressures.... :roll:

http://anotherairgunblog.blogspot.ca/20 ... art-1.html

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Last edited by Ace on Wed Apr 08, 2015 10:40 am, edited 1 time in total.
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