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MP-7 Hop-Up Problem


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#1 jake556

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Posted 11 September 2012 - 11:08 AM

I recenty got a used MP-7 and am having what seems to be a hop-up related issue.

When firing, BBs curve up with no hop-up (adjusted using tool) at all. The hop-up does function as it casues even more of a rise in the flight path when I increase hop. The other problem I am having is that due to low/no hop-up the BB's tend to roll out of the barrel.

I have completely dissasembled the airsoft gun (including hop-up) to ensure that there isn't excessive buildup of oils but the problem still remains. I have also removed the bolt and looked down the barrel on the hop-up side and adjusted the hop-up to verify that it is in fact increasing and decreasing. With no hop-up there is not any part of the bucking protruding in the barrel, yet I am still having this problem.

I am using KWA Perfect .25g BBs. Should I try a heavier weight? The MP-7 is all stock right now.

Thanks for the help.

#2 Outlaw1995

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Posted 11 September 2012 - 06:22 PM

Hi jake556. Sorry to hear the issue. My MP7 experienced the same thing when I bought it used. You are going to need to buy a new hop up bucking and ball. Luckily, KWA sells this as a package deal for only 5 bucks. The reason why you're bbs are curving up is because the hop up bucking ball bearing is not set, and may not be in the gun at all. Without the ball giving hop up/ contac on the bb, the bb will curve up dramatically during flight. The reason why bbs may be rolling out of the barrel is because you have a swelled hop up bucking. This is usually due to using heavily lubricated propane, and so the silicon oil gets on and swells the hop up bucking.

Anyways, you can buy a new hop up bucking plus ball bearing off the KWA pro shop: store.kwausa.com.

If you need a tutorial on how to replace the parts, see the video in one of the posts at the top of the MP7 sub forum for a disassembly/reassembly video.

Good luck getting that gun fixed!!

#3 jake556

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Posted 12 September 2012 - 10:29 AM

Thanks a lot for the advice Outlaw!

I'm currently trying to let the bucking soak in soap and water.

Regarding the ball bearing I actually called KWA and they stated that there isn't a ball bearing in the hop-up in the MP7. Any ideas?

#4 Outlaw1995

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Posted 12 September 2012 - 01:24 PM

Definitely let the hop up bucking soak in a lot of soapy water. If that doesn't fix your swelling issue, you will have to get another bucking. And I don't know why KWA says that the MP7 does not have a ball bearing hop up design, because it does. I've taken mine and my friend's apart and the way the hop up is adjusted by rotating the screw, applying pressure to the little ball. Here's a link to the product you will need to get if this soapy water trick fails. http://store.kwausa....pupbucking.aspx

If what you're trying to say is that the hop up bucking they sell does not include the ball, then you will need to buy the one with the ball, and also, they may have said the reason why you are experiencing this problem is because you don't have the ball inside your hop up of your MP7, which is the reason why your bbs are curving up when you shoot.

#5 jake556

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Posted 14 September 2012 - 06:21 AM

After letting the bucking soak and dry for a day it has a lot tighter fit on the barrel. Looking good so far.

Again regarding the ball bearing, I'll try purchasing the part you linked and try it. There may have been some miscommunication but the KWA rep I spoke with was sure there isn't a ball bearing in the MP7.

Opening your own gun and finding one though doesn't lie! :)

#6 jake556

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Posted 14 September 2012 - 09:57 AM

Ordered a new bucking with the ball in the picture (like the one you linked).

I will keep you posted!

Thanks for the help :)




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