GTA
All Springer/NP/PCP Air Gun Discussion General => American/U.S. Air Gun Gates => Crosman-Benjamin Air Gun Gate => Topic started by: IslandShooter on January 22, 2013, 01:14:29 AM
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(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/image_zps63fd9d7a.jpg)
Someone here said something about Crosman and their new breech screw being moved to the rear of the loading port...now my breech I just ordered clearly is on the forward part of the loading port.. Is this new or the old style?
Also, I installed the bolt in the breech, closed the bolt and it doesn't seal up the loading port. I shined a light at the loading port and looked at the barrel and I can see light coming thru...I am afraid I will have air coming out of there instead of blowing toward the muzzle..there is an o-ring on the bolt, yes.
Any ideas?
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its the old location
cant help you with the rest of your questions
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you could do what I did (I recently installed this same breech) - put it all together and test-fire it, just to see if I'd missed anything....
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Also, I installed the bolt in the breech, closed the bolt and it doesn't seal up the loading port. I shined a light at the loading port and looked at the barrel and I can see light coming thru...I am afraid I will have air coming out of there instead of blowing toward the muzzle..there is an o-ring on the bolt, yes.
Any ideas?
It seals against the inside of the barrel, not the breach. The bolt and o-ring need to match the caliber of the barrel you are using. Maybe you have a .177 bolt/o-ring with a .22 cal barrel.
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the bolt is .22 can tell by looking at it
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the bolt is .22 can tell by looking at it
Good eye! Comparing to the .177 bolt, I do see that the O-ring is further back and larger. Which leaves something wrong with the barrel?
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Not wanting to HiJack thread, do you have to drill a new hole in tube , when installing the new style breech? Inquiring mind's would like to know!
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Are you sure you have the barrel all the way in the breech? That would be my best guess make sure the transfer port is lined up.
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Not wanting to HiJack thread, do you have to drill a new hole in tube , when installing the new style breech? Inquiring mind's would like to know!
You would need to tap the hole in the tube as the rear one often will be threadless but it will be a hole. The hammer will need to get a clearancing to make sure it doesn't hit the Screw if you use the rear position. The Breech shown is the Early AS 2250XT breech and the rear mounting position breech is the later part. If fitted to the 2240 or 1377 the hammers will need to be modified so they don't hit the screw. If yoyu put it together and fire it a few times with the hammer unmodified you will create a mess it is very difficult to get APART.
TimmyMac1
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Alright got more stuff from Crosman. 18" 22cal barrel, pump arm, 2289 barrel band. oh and i got and extra bolt and bolt handle. i guess when u order an 18" 22cal barrel, they give u extra bolt and bolt handle..cool.
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1931_zpsc11e1c08.jpg)
Here is the barrel crown on each end. Doesnt look too bad but i might just shine them up just to be on the safe side. what ya'll think??
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1935_zpsbeb6cae5.jpg)
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1938_zps09e0f8d8.jpg)
Alright..so i will use the breech with the forward screw hole as this will eliminate modification so it doesnt mess up my hammer. also ya'll were right, the bolt will seal up to the barrel. once i got them in, it sealed. thanks all.
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So do you re-crown just the muzzle end or both end of a barrel? Confused?...???
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The edge that is at the exit of the barrel is the crown. The entrance to the rifling is called a leade. The leade is a gradual taper into the barrel to ramp the pellet in so it engages the rifling with minimal abuse to the pellet.
The Leade is very important to make sure the transition is not abrupt and rather than a step that can damage the pellet as it enters we seek to have a nice beveled entrance as smooth as possible to help the pellet enter the rifling without shedding debris.
The Crown by contrast wants to be smooth but there is no intrusion to the rifling but a very clean concentric release to the pellet that is burr free. The tools needed to do a crown Job are not in any way related to the tools needed to do a proper leade polish.
There is great opportunity to improve production leade and crowns so that accuracy can improve realtive to the production item. Done right there is never a loss of accuracy when these improvements are made but sometimes the improvements will be marginal. It mainly depends on what we find. Burrs on transfer ports, stepped leades, excentric crowns, rough leades, Burrs on leade transitions and ragged Production Crowns all give us the opportunity to improve the accuracy of a production barrel. Bellmouth muzzles and tight Breeches are about the only conditions we can't improve upon because these are generally counter to the what makes accuracy. The muzzle needs to be tighter/smaller than the breech or the barrel is likely scrap.
TimmyMac1
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The edge that is at the exit of the barrel is the crown. The entrance to the rifling is called a leade. The leade is a gradual taper into the barrel to ramp the pellet in so it engages the rifling with minimal abuse to the pellet.
The Leade is very important to make sure the transition is not abrupt and rather than a step that can damage the pellet as it enters we seek to have a nice beveled entrance as smooth as possible to help the pellet enter the rifling without shedding debris.
The Crown by contrast wants to be smooth but there is no intrusion to the rifling but a very clean concentric release to the pellet that is burr free. The tools needed to do a crown Job are not in any way related to the tools needed to do a proper leade polish.
There is great opportunity to improve production leade and crowns so that accuracy can improve realtive to the production item. Done right there is never a loss of accuracy when these improvements are made but sometimes the improvements will be marginal. It mainly depends on what we find. Burrs on transfer ports, stepped leades, excentric crowns, rough leades, Burrs on leade transitions and ragged Production Crowns all give us the opportunity to improve the accuracy of a production barrel. Bellmouth muzzles and tight Breeches are about the only conditions we can't improve upon because these are generally counter to the what makes accuracy. The muzzle needs to be tighter/smaller than the breech or the barrel is likely scrap.
TimmyMac1
As always, the great teacher! Thank you Sir.
As you said, the Leade looks good with a gradual slope toward the inner rifling. The Crown do seems like it needs some work at it has burs.
Also bought a TKO valve. It's all aluminum and the port is not modded which lead me to believe that it's all stock with stock spring. Here are pics
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1939_zps2797e383.jpg)
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1940_zps5eb9c988.jpg)
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1941_zpse2c40725.jpg)
(http://i1306.photobucket.com/albums/s570/680-7twenty/Air%20Gunning/DSCN1942_zpsf8ac55f2.jpg)
Hopefully I can use some small drill bit to open the port to something other 90degree angle. Now, any recommendation on spring? Going to try the trigger spring and find a replacement for trigger spring and add a hammer spring guide. I think the hammer spring guide will create more tension on the hammer...thus, stronger spring.
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I'd try a dremel over the drill. Drill can gouge or jam/break too easily. I'd also test it as the valve is, before doing any porting.
PS: I have some .22 barrels, bolt, and o-rings in my current crosman order. :)
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Lol man the parts just keep showing up! Mr mac 1 is by far the expert on these so you have good advice there. Congrats on the parts and fun of building. Cant wait to see the stats on the final build. Congrats and have fun!
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I'd try a dremel over the drill. Drill can gouge or jam/break too easily. I'd also test it as the valve is, before doing any porting.
PS: I have some .22 barrels, bolt, and o-rings in my current crosman order. :)
Thanks, i will try that, and good luck on the build too. I don't have a chrony so I will do the phonebook test....lol.