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Discussion Starter · #4 ·
Yeah that was the first thing I did. However, I just took apart the piston and found the culprit. The piston is a vacuum piston, and I'm thinking it will be near impossible to achieve 100% compression in the cylinder with this piston. Doing some research, people say the vacuum piston is more consistent, which does not make sense to me. If there is 100% compression, it seems like the piston would push out the same amount of air each time (of course assuming the spring never weakens and is 100% consistent itself, which is not true).

I'll have to think about this some more. Switching to the hard piston (as its called) or a piston that can handle a power accuracy cup piston head.

I'm looking at this thing trying to think of a mod I could do that would be durable enough for testing but reversible, nothing coming to mind yet...

Edit: I put a thick piece of plastic over the piston head and then put the o ring back over it to hold it in place. I got 100% compression, until it popped the plastic! So now I know what the problem is there, time to decide on a new piston / piston head combo.
 

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Discussion Starter · #6 ·
I was looking at the one last night. I just can't pull the trigger on it yet though, until I know my current piston is the weak link. I think for now I will either leave the vacuum piston as is, and move on the the hopup / cylinder head seal, or try and do a non permanent mod to the air release valve in the vacuum piston. Fill the hole with an epoxy or something, not sure yet.

EDIT: OK, tonight I decided on a semi permanent solution to the vacuum piston leaking air. I used some steelstik, filled the chamber that houses the little rubber ball in such a way as when I screwed it back together (after it had cured) it forced the rubber ball deep into the intake hole. So even if the steelstik doesn't create a perfect seal, the rubber ball forced further into the hole will (in theory). I have 100% compression in the cylinder now, no matter how long I hold it. Good stuff!

I have used steelstik before, but never for applications where there is pressure and lots of pounding abuse. It will be interesting to see how it holds up to the punishment of existing in a cylinder with a 430fps spring.

On to the pdi hopup unit with the two potential leaks, cylinder head to hopup bucking and bucking to barrel. I cant find ABB devices for sale anywhere, and not too excited about trying to cut my own, but I do have a few ideas (will try the floss or wire mod).

Also, have any other maruzen type 96 owners noticed when the outer barrel is screwed all the way on, it's not in alignment with the receiver? I'm thinking some careful sanding down of the barrel edge (with the threads) can solve this, but I'm a bit nervous to try it just yet.
 

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Discussion Starter · #8 ·
Yeah, the cylinder now has excellent compression. I am moving on to the hopup area. Need to wait for a few different bucking to be delivered though. On a side note, anyone know where I can get nub less buckings? Would be easier than trying to sand off the nubs.
 

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Discussion Starter · #10 ·
Cheese Man said:
I don't think anyone makes them...
I saw that noobie makes some, but they look like they are for the vsr system, and even then it doesn't look like he is selling stuff at the moment. I might have to look into molding buckings. The nub is driving me nuts, and even when its sanded down it leaves imperfections that could cause inconsistency.
 
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