On I go…
The cocking bar, that part of the cocking linkage that pushes the piston back.
I don’t know why it has that square bit. Possibly a sort of anti-beartrap? Hmmm.
One trigger pin pushed out.
The sear is odd, there’s a ball bearing on the sear and one on the piston.
The trigger and its two pins.
I couldn’t remove the “cocking body”.
The pin just wouldn’t come out more than this and I did not want to destroy the gun.
The rear sight.
A setscrew locks the plug to a cross-pin.
I was too lazy to drag out my spring compressor so I just used a bar clamp. The spring does have a significant preload.
Pushing the cross-pin out
The end plug. Notice the integral cruciform spring guide.
The piston.
See the ball? Shiny ball
.
The piston seal is a simple slug of molded elastomer. I forgot to take pics but it has a groove on the underside as it’s molded. I think an easy replacement would be an aluminum slug with an o-ring.
All the parts…
Here’s a poor shot of the two sear balls in contact, representing a cocked condition. When the trigger is pulled the one ball slowly rotates out of contact, which yields a sliding motion as the sear releases. Not crisp, but smooth.
Anyway…reassembly is exactly in reverse. I took some time to properly lube everything. The gun does shoot smoother than before.
4 comments:
Thanks for a great job describing the dissasembly. The piston seal on my Manu-Arm is completely disintegrated. For this newbie, what's your recommendation for a replacement seal? Is the aluminum slug with an o-ring that you mention something that is commercially available?
TIA,
Frank
Wow. Are there many examples of spring airguns that use o-rings over traditional piston seals? Seems like once the o-ring wears out a bit, the narrow surface area of the o-ring would allow lots of bypassed air, and result in some that piston slamming pretty hard!
Frank,
Not available, but something you could do with a lathe. I don't know of any commercially available seal replacement. Possibly you could find a seal of the proper diameter (Maccari?) and make an adapter as well. Or you could even make a leather seal.
Ryan,
Sure, tons of airguns use o-ring type seals. Not as wear resistant as a parachute type seal, but they do work. The Meteor I resealed a while back had one.
A little bit of help
Hello!
First of all thanks for this post! Forgive me because i don't speak English, i hope you can understand my problem.
I've also got a MANU-ARM cal. 4,5 mm and i can arm no more. I opened up the 2 plastic pieces and i remove the triger pin to see what is wrong with it. It is nothing broke or missing. I think maybe is something wrong with the 2 balls system but i don't really know how that arm system it's working. I hope you have 5 minutes to say me how i can shoot again with my MANU-ARM.
I'm waitting for an answer on e-mail: alexpahomi@yahoo.com or like a comment on this post.
Thank you very much!
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