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MP7 Rocket Valve Spring, not a good choice


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#1 akiraspeedstar

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Posted 18 January 2013 - 08:57 AM

Even though after modifying my Dangerwerx valve to get the desired FPS, I wanted to replace my cut OEM valve spring. While I was at AONW, I felt I had to buy something as I drove out there and couldn't leave empty handed, so I checked to see if they had any rocket valve springs and they had one for an MP7. I compared it to the OEM spring and the diameter seemed the same though the length was a little longer. After installation it operated smooth so I didn't think anything of it.

Looking back, a lot of minor issues began to surface after installing the spring. The only downside is that I installed other parts at the same time. Gas efficiency seemed to be an issue, though it was sporadic. When I took out the WA spring, it seemed to help. When I later had issues with the A2 buffer and swapped back to stock, it seemed to help. When I changed out my Madbull Propane adapter with a AI, it seemed to help.

Well last night my gun completely crapped out on me. The shots were inconsistent, it jammed, it didn't cycle fully, it would vent all of the gas, then at on point it wouldn't fire any BBs. Unfortunately, before this game I had installed the RA-Tech super recoil kit, Guarder bucking, and the AEG Magazine catch. Considering I've shot the gun so many times with the RA-Tech kit, I didn't think it was that. The guarder bucking or the magazine catch (possibly having the magazine at a bad height) seemed to be the possible suspects.

Also to note, whenever I previously checked the bolt, everything operated correctly.

Anyways when I got home and ripped apart the gun the magazine catch was the same height as the OEM and the Guarder bucking was installed correctly. It turns out the MP7 Valve spring had jammed itself into the piston. Honestly I had completely forgotten that I had even installed the MP7 Valve spring. Due to the difference in length the spring would at times bind and in this case finally jammed completely. Testing the valve (compressed air and holding the piston in my hand) the valve would sometimes not close completely or it wouldn't reopen. This completely explains why the gas would vent as if it was running cold (which it would then become cold), why it wouldn't fire that day, why it jammed (BB actually didn't fire then the nozzle tried to load another BB), etc.

So either...
1) That's not even an MP7 spring and I was given the wrong one

or

2) MP7 Spring is bad Juju

Lesson learned, always remember what parts you install into your gun *face palm*

Edited by akiraspeedstar, 18 January 2013 - 09:09 AM.


#2 dos_Santos

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Posted 18 January 2013 - 01:09 PM

What I appreciated about your malfunction, was that I didn't get hit by your BB's when you had me dead to sights, lol.  Good times.

#3 akiraspeedstar

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Posted 18 January 2013 - 01:42 PM

One of you guys shot out my flash light haha. Already fabricated a polycarbonate lens for it.

#4 dos_Santos

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Posted 18 January 2013 - 02:21 PM

Dang!  You shot me in the finger tip, that hurt like a holy mother.

#5 gcw360

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Posted 18 January 2013 - 07:32 PM

View Postakiraspeedstar, on 18 January 2013 - 01:42 PM, said:

One of you guys shot out my flash light haha. Already fabricated a polycarbonate lens for it.
Lexan is your friend....




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