GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: redlined_b16a on December 23, 2024, 03:49:41 PM
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To start the intention of this post is so that others can learn and maybe save a life or injuries.
I am in contact with Airforce on the situation and I was extremely honest with them admitting my faults and concerns.
From the beginning
Dec.2nd ordered a Texan .357 Carbine from an online airgun supplier(No names mentioned)
Arrived December 15th
Dec.20th filled up the tank to 2900 psi
Fired about 20 rounds through it experimenting with hammer tensions.
Ammo is casted from a Lee mold 150 grain .358 and I size gem through a die at .357 they fit tight in the breech and I can only put 5/8 of the slug in the chamber
4th fill up
2900 psi Carbine pushed its first round at 830 fps with %90 hammer preload
Second shot 828 fps and air leaking out of the barrel.
Minimal leak we could barely hear it when we opened the breech.
At that point we let the air bleed to zero from 2600 psi on the Airforce gauge.
Researched and found a thread on another forum where this happened on another Texan.
Guy removed the valve(Top portion)and top hat to fid a tiny split in the poppet.Contacted Airforce and they sent a new upper valve.
So it was after 5 by the time we tried to contact Airforce.....closed till Monday.
My mistakes start at this point.
Removed the poppet saw the tiny split.
Decided let's pressure it up a lil to see if its still leaking......knowing it leaked previously.
Filled from a 65 minute 4500 psi scba which had 3600 left in it.
Got to 1000 psi I submerged the tophat into water and no leak was present.
Keep in mind the tank was off of the gun.
Filled to 2000 psi and I just bleed down my hoses to check for leaks again.
As soon as my pressure bleed down as I reached to un hook the quick disconnect.
Heard a loud pop and a blur in vision
The Airforce tank shot off the table like a rocket pulling the 15 pound 65 minute scba with it.
It launched 15 feet across the room destroying everything in its path.
My brother and friend were just standing in that spot seconds before.
All the dust settled and now it's time to see what the pain in my arm and damages are.
Top hat became a bullet and struck the counter and bounced into my forearm.Minor bleeding and bruising.
The Airforce tank beat up,valve in pieces,female QD broke and the male foster fill is bent and out of round.Gauge has scoffs
Numerous broken items in the room.
So what happened?
The poppet split at some point.
Pressure behind it parted the poppet in two
Since the tank was not in the gun the top hat was propelled like a bullet from the tank dump.
My advice to you is
If your Texan is leaking.......DO NOT REFILL IT WITH THE LEAKING PARTS
Had the tank been on the rifle I believe no one would have been in any real danger.
Airforce thinks my slugs were too loose and that can cause the poppet to slam closed too hard.
Or Ammo is to lite.
They are sending another tank and valve assembly.
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Also today my Texan SS .357 which has about 100 rounds through it.......is also now leakingvand the poppet has split as well.
Using a diffrent 150 grain sized to .357 casted in lead ammo.
What is going on?
My SS is weaker aswell.
Two Texan .357 platforms splitting valve poppers.
The SS split at 2400 psi on shot 5
Brand new guns.
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It must be a rear bottle big bore issue, I'm having similar issues with another brand. Been lucky no valves launching bottles yet ;) Ouch!!! :o
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Houston we have a problem!....
Glad no serious injuries, that looks bad enough....
Bob
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I have the symptoms of lite or loose fitting ammo
The carbine the .357 is tight
Both guns to me are anemic
The SS and carbine are supposed to be 790 fps with170 grain.That came from Airforce directly.
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So why a a delrin poppet?
I remember older Benjiman Sheridans with brass poppet with rubber o-ring style seals.
Just because you can does not mean you should.
Made a test part and it seems like it would function but I'm terrified........90 durometer oring.
Aluminum poppet.
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I rather doubt the O-ring will stay in place.... To clarify, I meant during firing....
Bob
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I rather doubt the O-ring will stay in place....
Bob
I machined it into a tight groove
The large aluminum supports the oring on the pressure side.
I'm no engineer or machinist.
Might put 500 psi on it and let it hold a couple hours.Slowly increase pressure
Drop the hammer tension very low and try to sling some pellets
I don't want to take another valve to the flesh again.
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I rather doubt the O-ring will stay in place....
Bob
Neat experiment lol.
2000 psi took 3 shots and tank dump
Achiever 4 fps
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Sounds to me like airforce has a bad batch of poppets. Probably trying to find a cheaper supplier of either the poppets or the delron(?) the poppets are made of.
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Delrin and acetal are both engineering plastics with similar properties, but there are some key differences between them:
Chemical resistance-
Acetal is resistant to hydrocarbons, solvents, and neutral chemicals. Delrin is resistant to chemical corrosion and weathering.
Temperature resistance-
Acetal is well suited to constant high-temperature exposure, while Delrin doesn't perform well at high temperatures. Delrin's temperature range is between -40 degrees Celsius and 120 degrees Celsius, but it can't maintain high temperature resistance for long.
Mechanical properties-
Delrin is the stiffest and strongest unreinforced technical engineering polymer available. It has a uniform backbone with a larger crystalline block structure than acetal copolymers, which provides better chemical bonding.
Machining-
Both Delrin and acetal are easy to machine in the proper temperature range. Acetal has less chance of centerline porosity than Delrin.
Cost-
Acetal is the better choice for maker projects as Delrin can be more expensive.
Applications-
Delrin is used in various aerospace, automotive, and medical applications. Acetal is a popular choice for replacing mechanical parts, such as gears, clamps, and spacers.
I'd also guess bad material batch?
For a discharge valve a solid poppet made from a tough material like delrin should work well. No o-ring there as the high velocity flow will try to dislodge it and eventually succeed.
A poppet valve with an o-ring seal could work fine as a fill/check valve... lots of little burps of lower velocity fill air is much less likely to dislodge the o-ring.
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Made an aluminum/nylon poppet but just can get it to 100% seal......barely leaking.
Wish Airforce would actually ship my parts.......been told several times it's ready to ship.