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MP7 Hop up problem/bucking problem?

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#1 Havoc Siege

Havoc Siege


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Posted 01 June 2014 - 05:31 PM

Thanks for checking out my post, its my first time posting on a forum. I would like a little bit of help with a problem I am havig with by brand new KWA MP7. I got it from Evike on Memorial day because it was a deal at 200$. Anyways, when I recieved the item, the first thing I did was went out and shot it to see how well it shot. I was not very impressed. About maybe fifty feet out, the BB curved extremely hard to the right. I was useing .25g bb's at about 380 fps (chrono'd with .25's).

I knew istantly something was wrong with it because I had watched so many videos on the preformance, and everyone seemed to have theirs shooting in a straight line. I took the the bolt out so I could see down the barrel and adjusted the hop up, and what I saw was when the plunger pushed down on the bucking the bucking would come down to the right more than the left. It was not even at all. Im not sure if its the buckings fault, or if it is the plunger that is not working right.

What do you guys think? Any suggestings on where I should go from here? I took the gun completely apart and took out the plunger, then shaved the end down a bit and rounded it out more smoothly, but not even that helped anything.

Thanks for the help!

#2 905taylor905



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Posted 03 June 2014 - 05:33 PM

Hey havoc.
Sorry to hear about the troubles with your mp7.  Unfortunately I am also plagued with this problem and have been for quite some time now.


My original problem was, with one click of the adjuster, the bbs would be curving up very strongly after about 50 ft, one click down and no hop at all.... Turns out my stock bucking was torn and needed replacing.

I purchased an angel custom v type bucking and I noticed right away in the plunger hole, my bucking divot wasn't lining up right with the plunger hole, causing the plunger to push down a little to far forward and not actually in the divot at all, so when applying hop up i couldn't see the bucking teeth down the barrel, but the rim in front of the teeth bending down, causing the loading end of the bucking to shape a little ovalish.   Tried it out and sure enough same hop up issue.  So I had to shave a touch off of the front of the bucking (bb entry side) to make it all match up.
(I believe now I just got a deformed bucking)

After that the hop up adjuster was not nearly as touchy and I could give a few clicks before noticing small hop up increases in its path.  That's when the infamous curve became my issue.

I put everything together and looked down the barrel while applying hop up and noticed the left tooth would always stick down farther in the barrel than the right tooth would.   No matter how many times I set it, it would always show more on the left tooth.   So I Teflon taped the bucking tightly in place and it shot well for about 4-500 rounds until slowly gaining more and more of a leftward curve. (No not the wind).  So I opened it again to notice the left tooth showing more again.  I believe the bucking I received was deformed a little bit and will not allow for proper flight path because every time it settles it is shooting to the left.    I know there is nothing in the barrel from the flash hider glue, I have checked thoroughly.

I was thinking about shaving down the teeth a little until they even out but I have been fitting for months and it is getting frustrating!  

One option is to buy the maple leaf barrel and hop up kit for the mp7.     It looks promising.
Here's the link for ehobby.

Edited by 905taylor905, 16 June 2014 - 07:02 PM.

#3 SR105



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Posted 12 June 2014 - 03:52 PM

There are only a few reasons why a BB would curve coming out of a barrel.

1) The inner barrel and hop up bucking are not aligned correctly. This is not likely since you cannot install the MP7 inner barrel and hop up bucking unless it's sitting properly
2) The bucking is not molded correctly. It sucks, but happens sometimes.
3) Debris in the inner barrel. This may include glue or thread locker that is put onto the flash hider from the factory. Some of it may have made its way into the inner barrel before it dried completely. The only way to tell is to hold the inner barrel up to a light source and see it
4) Inner barrel is warped somehow.

The easiest thing you could do right now at home would be to clean the inner barrel with a dry swab. Don't use any liquids to clean it. Just use a small square of tissue paper can clean very well.

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