photo toplogo1_zps46807118.jpg

 photo ef7e91f7-efed-4c80-9d93-6fb3d862a8cc_zps0bafaaa9.jpg

Barry McGee's Custom 2300

Cothrane stainless tube, left handed breech, power adjuster,
Lothar 10" barrel, H.P.A.sports co2 cap, Clague ldc,1701 trigger group,
Stace trigger, Rick Andres grips and a Mueller quick shot reflex sight.

  << Previous Topic | Next Topic >>Return to Index  

OK 9mm barrel has been ordered. Now what?

February 8 2012 at 10:07 AM
Mike  (Login lowridr)
Crosman Forum Member
from IP address 129.119.241.47

What do I need to do so my 2240 can handle the pressure of a PCP charge? The main tube is stock but the valve has been modified internally. Very good trigger work if I do say so myself. I plan on going bulk.
Thought I would start with a longer tube and later go to a bottle on the back. Jump in any time. Thanks



 
 Respond to this message   
AuthorReply

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

wait , hpa or bulk fill?? with co2

February 8 2012, 10:27 AM 

u will need to dump a massive volume per shot to get those 9mm rds moving, with hpa u will need to seriously modd the crrent tube but it might be easier just to order a prod tube for 125 and save urself all the risks , like pinning the valve , installing a foster connection , installing a gauge etc.. Id go co2 , and make that valve dump a huge volume of c02 , hopefull get 330fps or so which would be like ~16fpe of killing power

[linked image]
"i never was much for book learnin"

 
 Respond to this message   
Phil
(Login Duane30)
Crosman Forum Member
74.140.196.166

Several things to note on such a build...

February 8 2012, 10:30 AM 

The valve will need to be pinned radially with screws. An absolute must - don't slack on this, or you may be sorry you didn't. Do a search on here.

A 2240 will yield way to little volume to go 9mm PCP. I'd suggest getting a PCP tube from Don Cothran's shop http://www.cothranmachine.com/). A 2260 and/or a Discovery tube, for volume AND pressure reasons. Don's tubes can withstand a great deal more pressure.

A Crosman steel breech will work for the barrel liner you ordered. However, you will need to have it bored out AND a probe made to match. Don can do up a breech and probe for ya' that will bolt right on.

The transfer port will need to be opened up to .21", or so.

There are number of hits on this site that can be accessed via the search function.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

yep

February 8 2012, 10:45 AM 

unless hes looking for a critter gitter like decvice for only 200 to 300 fps , a close range bird smasher. id even prefer to put this barrel on a 39x gun and work the AC concept .

[linked image]
"i never was much for book learnin"

 
 Respond to this message   
Jack Witas
(Login boomerdude)
Crosman Forum Member
76.24.9.142

Is Don still in business?

February 8 2012, 2:43 PM 

His new site disappeared and I've tried to order from him several times with no response.

 
 Respond to this message   
VAF
(Login VAFarmer)
Crosman Forum Member
165.214.14.23

I am just getting into modding 22 series guns, but

February 8 2012, 12:20 PM 

Roy Weid emailed me back and said that stock tubes were not meant to do more than 1k psi.

Reason was I had asked about HiPacs. Now, don't know if that is 100 percent accurate, and I may be repeating it wrong, so take with a grain of salt.

I will still end up getting a hipac for mine once it arrives, but just wont fill to over 1k. Even if its only good for 10 shots....heck, the only reason I will go hipac anyway is to be able to hunt this gun in winter temps......hunting, if I take more than 10 shots, then its cause Im missing.

By what I have read, you will need optimized dwell time, and a long barrel to realize the most potential. good news, larger the cal---the more efficient the co2 happy.gif


God bless,

Farmer

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

hipac concerns

February 8 2012, 12:29 PM 

the tube could actually handle over 3000psi , or vastly more lets assume. but the valve has nothing substantial holding it in place , and the threading on the hipac to 2240 tube would fail at some point , etc... So its not really the tube , its the way the other parts are connected.

[linked image]
"i never was much for book learnin"

 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
72.25.192.4

You have that all wrong Rob

February 8 2012, 12:56 PM 

The only force on the tube threads comes from the sealing diameter of the 'powerlet' and fill pressure.

Walter....

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

even in hipac mode???

February 8 2012, 1:41 PM 

something has to be holding the pressure back from disconnecting the 2240 from the hipac rig.
[linked image]
"i never was much for book learnin"


    
This message has been edited by robnewyork from IP address 108.21.103.165 on Feb 8, 2012 1:42 PM


 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
72.25.192.4

Could you calc the forces?

February 8 2012, 1:45 PM 

be a good exercise

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

well u have the tube diameter

February 8 2012, 1:48 PM 

lets asssume the worst case snenario that the hipac does not reduce down the exchange area flow. that would be 1000 psi times the sq inches covered by the tube I.d (r times r times PI ) , yeilding the number of lbs trying to push the hipac system off the 2240..
Im sure he reduces that channel to .25inches or less thus dispersing the pressure over different plains.

[linked image]
"i never was much for book learnin"


    
This message has been edited by robnewyork from IP address 108.21.103.165 on Feb 8, 2012 1:49 PM


 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
199.96.209.157

Okay lets do the math

February 8 2012, 7:07 PM 

The pressure inside the Hipac will be max at 3,000psi
tip of the seal is at 0.250" diameter
this will generate a force of 147 pounds against the valve reatining screw and the tube threads

The valve screw is a 6-40 with a diameter of 0.107" will see a stress of 16,333 psi. so no troubles

The tube thread at 13/16 x 28 and a 0.875" o.d. will see a stress of 925 psi. no troubles.

I would replace the valve screw with an 8-32 low profile SHCS as the head is the right size for the tube and makes for a better job.

in reality teh HiPac is a good way to allow powerlets and air without change to the base airgun.

Walter....


 
 Respond to this message   
robert
(Login gubb33ps)
Crosman Forum Member
68.105.50.68

Walter has it figured...

February 8 2012, 7:33 PM 

..and really, if you had one in hand, would make more sense to you.

What I find is that if you do manage to over pressure one of the HiPacs (yes..have tried it), it will leak at the seal between the HiPac tube and the valve (it seals as if it were a big long 12gr.).

As mentioned, valve retention is really important, but so is NOT cranking on the HiPac like it was a lug nut on a truck. Can really deliver much more than 3K's worth of air stress to the retention screws by over tightening.

The only other major factor is that the air volume is small. Even with the long 2260 Conversion, its a very thick walled unit that slides inside a 2260 tube..the internal diameter is much smaller than you'd first guess, so the volume is smaller than the length would lead you to guess.


    
This message has been edited by gubb33ps from IP address 68.105.50.68 on Feb 8, 2012 7:34 PM


 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

none of my math or reasoning was flawed , and ive never held a hipac,

February 8 2012, 7:59 PM 

PLEASE POINT OUT MY MISTAKES . id appreciate it
[linked image]
"i never was much for book learnin"


    
This message has been edited by robnewyork from IP address 108.21.103.165 on Feb 8, 2012 8:00 PM


 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
199.96.209.157

well let's see....

February 8 2012, 8:18 PM 

lets asssume the worst case snenario that the hipac does not reduce down the exchange area flow.

*******I have no clue what you mean by this statment, sorry.....

that would be 1000 psi times the sq inches covered by the tube I.d (r times r times PI ) , yeilding the number of lbs trying to push the hipac system off the 2240..

****** so you would get 442 pounds force pushing the assembly apart at 1,000psi
******* neither that pressure nor piston size exists in the HiPac assembly

Im sure he reduces that channel to .25inches or less thus dispersing the pressure over different plains.

****** again, I cannot understand the mixture of terms here that do not apply to the HiPac
****** what do you mean by channel?
****** what do you mean by dispersing?
****** what do you mean by different plains?

Sorry Rob, but that is what we are left with.

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

a good example

February 8 2012, 8:23 PM 

the way the disco gauge is attached to the disco , the direct pressure is offset by reducing the face area to a mere pinhole , so in affect the actual lbs the gauge is holding back is sub 100. (.050sq in @ 2000psi =100psi ) all guesstimates but i asssumed hipac also offset these pressures off the stock thread in some fashion. I didnt elaborate on much else, just the potential force on the stock threads , which you determined to be 442lbs if the device is configured as a straight screw on item.

[linked image]
"i never was much for book learnin"


    
This message has been edited by robnewyork from IP address 108.21.103.165 on Feb 8, 2012 8:24 PM


 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
199.96.209.157

Sorry Rob, this needs more explaining

February 8 2012, 8:31 PM 

A pressure acts on teh diameter at which the sealing occurs. Where teh pressure differential exists.

The 442 pounds comes from my limited understanding of your description of the tube diameter and 1,000psi. The actual force in the Hipac assembly at a full 3,000psi is only 147 pounds. nothing really.

The disco guage is sealing at a diameter of say 0.375 and a pressure of 2,000psi acting on that
means there will be a force on teh gauge threads of 222 pounds.

The size of a port has zero to do with reducing pressure when no flow exists through the port.

when there is flow through a port that is a different topic.

walter....

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

in the hipac case there would be flow through the port

February 8 2012, 8:36 PM 

so not knowing the port size one could only assume the pressure on the threaded connection , i have no idea where u got 222, i have to go look at my 2240 cap and measure it to make more sense of that -boring topic , were the device in front of me , with a micrometer , i can do math . I wonder why crosman used that disco stem if not to reduce the force on the face of the valve ?

[linked image]
"i never was much for book learnin"


    
This message has been edited by robnewyork from IP address 108.21.103.165 on Feb 8, 2012 8:58 PM


 
 Respond to this message   
Glover, Walter
(Login Voltar1)
Crosman Forum Member
199.96.209.157

222 pounds force came from your 'example' of the Disco gauge

February 8 2012, 9:00 PM 

The disco guage is sealing at a diameter of say 0.375 and a pressure of 2,000psi acting on that
means there will be a force on teh gauge threads of 222 pounds.


Flow through the HiPac tip will occur each shot but due to the choked design the pressure at the seal will be less than the static pressure so reducing the force. The maximum force on the assembly occurs at 3,000psi when filled. After that pressure drops reducing force as well as when flowing force is reduced.

 
 Respond to this message   

robny
(Login robnewyork)
Crosman Forum Member
108.21.103.165

"""but due to the choked design the pressure at the seal will be less than the static

February 8 2012, 9:10 PM 

what ive been trying to express the whole time too a tee.

[linked image]
"i never was much for book learnin"

 
 Respond to this message   
 
< Previous Page 1 2 Next >
  << Previous Topic | Next Topic >>Return to Index  

Crosman Corporation 1-800-724-7486