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Mp7 Shoots 2 BB's with one trigger pull

Mp7 shoots 2 bb 2 bbs at once

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#1 Oldpouto

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Posted 08 July 2013 - 12:09 PM

I recently got this gun and I love it, My problem is that sometimes it shoots 2 BB's with one trigger pull, it looks like the mag is feeding two of them in the chamber at once somehow because I tested it multiple times by putting 10 BB's in the mag and shooting them in single fire and counting how many shots I get. I often got 8 or 9 shots out of 10 and every one of them fired something (hard to tell if it was 1 or 2 bbs as I was shooting in a pool at close range) And there were no stuck bb's anywhere they all shot out of the barrel only that some of them shot two at the time. What could cause this and how to fix this?

#2 Boss302

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Posted 08 July 2013 - 02:36 PM

I to am experiencing this problem with a relatively new mp7.  I don't know if its because the hop up is not on or the bucking swelled?

#3 gcw360

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Posted 08 July 2013 - 05:30 PM

View PostOldpouto, on 08 July 2013 - 12:09 PM, said:

I recently got this gun and I love it, My problem is that sometimes it shoots 2 BB's with one trigger pull, it looks like the mag is feeding two of them in the chamber at once somehow because I tested it multiple times by putting 10 BB's in the mag and shooting them in single fire and counting how many shots I get. I often got 8 or 9 shots out of 10 and every one of them fired something (hard to tell if it was 1 or 2 bbs as I was shooting in a pool at close range) And there were no stuck bb's anywhere they all shot out of the barrel only that some of them shot two at the time. What could cause this and how to fix this?
I'm guessing that either the hop-up is up too high or the bucking is swollen.  Either way the result is basically the same, the occasional jammed BB and double feed.

#4 Oldpouto

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Posted 12 July 2013 - 04:50 PM

There is no BB jamming, as I said, I put 10 BBs in the mag and get 8-9 shots... There is no dry shot...
My theory is that the BBs enter and exit the mag too easily and an extra BB might be blown into the barrel as the bolt is blown back... Unfortunately I don't have a high speed camera to check if i'm right, but if I am, finding a way to tighten the mag opening might do the trick...

#5 MustacheJason

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Posted 30 July 2013 - 11:43 AM

Quote

I don't know if its because the hop up is not on or the bucking swelled?

Well, the MP7's hop up is notorious for breaking. I use my MP7 for my local CQB field where shots are taken from 5-45 feet (yes it's that small), so i don't adjust the hopup.


Quote


What could cause this and how to fix this?

Check to see if the mags are double stacked. Not having a double stacked mag COULD cause the problem you have. Other than that, it may be hop up as well.

#6 Boss302

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Posted 10 June 2014 - 03:56 PM

I know this is an old thread, but I finally got around to changing the bucking to see if that was what was causing double feeding.  But even after putting in a new hop up bucking it would still double feed every 10 or so shots.  I did notice that the loading nozzle (the part that pushes the BB into the chamber) was rounded off a bit.  Could this be why it's causing double feeding?

#7 Chuck S

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Posted 10 June 2014 - 05:36 PM

Photos?

I can compare to mine (which ain't double shoting).

-- Chuck

#8 Boss302

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Posted 11 June 2014 - 06:00 PM

Here is what I got.Attached File  20140611_194912.jpg   28.43K   8 downloads

Edited by Boss302, 11 June 2014 - 06:12 PM.


#9 Chuck S

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Posted 12 June 2014 - 02:48 AM

Too small for me to see anything...

-- Chuck

#10 SR105

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Posted 12 June 2014 - 03:30 PM

From my experience, a double feed in an MP7 is typically these:

1) The follower in the magazine is getting weak. What this does is, when the bolt is traveling backwards, the tension on the magazine spring does not push the BBs up fast enough into the resting position in the magazine lip. Instead it skips off of the front of the cylinder and when the cylinder is on its way forward, it loads yet another BB.
2) The cylinder loading nub is rounded, essentially causing what I described above.
3) The cylinder springs are starting to lose tension, which does not pull the cylinder back fast enough and the same situation happens where one BB skips off the cylinder on the back stroke and another BB is loaded on the forward stroke.

So the most common issue that I run into for double feed has something to do with magazine follower spring, cylinder, or cylinder springs.





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