GTA
Airguns by Make and Model => Benjamin Airguns => Topic started by: glmthomas on September 03, 2015, 12:21:14 PM
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Hello,
I own a Benjamin Trail NP and need to replace the NP piston. Where can I find instructions to perform the disassembly, replacement, and reassembly.
Thanks for any help you might be able to supply.
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I don't know how mechanically skilled you are but I know of no instruction set specifically for replacing the Nitro Piston. You will require some sort of spring compressor.
I would first remove the scope and mounts if you have one. Remove the stock - two screws on the forearm and one accessed through the trigger guard. Caution, some trigger guards are a brittle plastic and will break with very little pressure. There are a couple of small parts which may drop off. Watch for them.
Remove the rounded plastic end cap from the gun. Only friction holds it in place. Place what remains in your spring compressor. Remove the long square bolt which accepted the stock mounting screw. Now put enough pressure on the spring compressor to equalize the force from the gas spring. The cross pin should be under little lateral pressure and a few light taps should dislodge it. If much force is required to remove it that means your spring compressor has too much or too little pressure on it.
With the pin removed you can back off the spring compressor. The trigger group will need to move back slightly to remove it. You will probably want to disconnect the anti beartrap linkage and spring at this point. It may take a tap or two to move the trigger group as sometimes they stick. Pay very close attention to how the pieces come apart. You may wish to take pictures.
With the trigger group out of the way everything else can be removed from the cylinder, though need not be. Pay very close attention to any spacers which come out with the gas spring.
Reassembly is the reverse of disassembly.
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Welcome to the GTA.
Richard
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Welcome to the GTA 8)!!
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Hi Mike,
There are several you tube videos on the web that show this procedure. Read Roadworthy's description a couple of times and have at it. But as he said be very careful with the trigger mechanism. I liked Pyramyd Air's video on this. It's a cleaning video but it's the same procedure.
Good luck,
Pellet Fun
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Mike, I have taken this rifle apart many times. I could do it with a blindfold (like I had to do with my H&K G3 when I did my 18 months in the German Army a long time ago...). Feel free to PM me and I will coach you through the process.