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-   -   KWA MP7 Double feeding like a mofo (https://airsoftcanada.com/showthread.php?t=139459)

djKail April 20th, 2012 17:08

KWA MP7 Double feeding like a mofo
 
Was really excited to field this tomorrow, however after obtaining my new silencer the gun seems to be acting up.

For every 10 shots I load into any of my three magazines the gun double feeds 2 - 3 times. I am using propane, and King Arms 0.25 Bios. Any ideas?

ShelledPants April 20th, 2012 17:13

Did the problem start when you added the silencer?

If so, it's possible it's not a double feed, but the bb is hitting the inside of the silencer and cracking in half. It would not be the first time I've seen this.

djKail April 20th, 2012 17:42

Actually it did but I think it happened this way by chance. I have been testing it without the silencer or suppressor with the same results. Everything is brand new as well, so it can't be the feed lips on the magazines. I also removed the bolt for cleaning and lubing but to no avail. I can understand a double feed now and again, but 3 out of 10 shots seems pretty bad

ShelledPants April 20th, 2012 17:45

Quote:

Originally Posted by djKail (Post 1642028)
Actually it did but I think it happened this way by chance. I have been testing it without the silencer or suppressor with the same results. Everything is brand new as well, so it can't be the feed lips on the magazines. I also removed the bolt for cleaning and lubing but to no avail. I can understand a double feed now and again, but 3 out of 10 shots seems pretty bad

I want you to load 10 BBs (not more) into the magazine, and see how many double feed. I have a theory. Repeat this a couple of times if it doesn't double feed (I have a feeling it wont). *Sometimes when a magazine is loaded to the max with BB's (like 60 rounds in a 40 round magazine...) the pressure from the magazine spring will push bb's very quickly into the chamber before the nozzle can block them off. Which, because the gun is designed to feed a full magazine, means the nozzle isn't returning to battery fast enough ... which says a lot because the MP7 is really fast firing.

djKail April 20th, 2012 17:53

Hey, actually that is how I was counting. I was loading the Magazines with only 10 rounds. I would then count the number of shots before the bolt would lock. I would get on average 7 - 8 before the bolt would lock.

Could it be the BBs? I have never had an issue with King Arm Bios in my WE SCAR?

ShelledPants April 20th, 2012 18:03

Yep. Try that too. BBBastards are a good choice.

Crunchmeister April 20th, 2012 18:34

I suspect BBs are your issue. Could be wrong, but bios often cause issues.

HeadlessChicken April 20th, 2012 18:37

I was about to suggest trying BBBs, I have the same MP7 and never had issues with them but did with other brands.

Danke April 20th, 2012 18:51

On the MP7 hopup rubber swells up from silicone oil.

The fix is to change it out.

Then use less oil when lubing your mags and don't apply it to the rubber.

djKail April 20th, 2012 19:49

Quote:

Originally Posted by Danke (Post 1642066)
On the MP7 hopup rubber swells up from silicone oil.

The fix is to change it out.

Then use less oil when lubing your mags and don't apply it to the rubber.

I did a bunch of research before purchasing the gun. I am aware of this issue and only put one drop of oil on my propane tank before installing the nozzle. I highly doubt my bucking is swelling when I have only put 4 or 5 magazines through the gun. Would that cause double feeding anyways? a BB always fires, none ever get stuck in the barrel, just double fed for some reason.

I am going to try some BB Bastards tomorrow and hope it solves the problem.

Summers1000 April 20th, 2012 19:58

Quote:

Originally Posted by djKail (Post 1642095)
I did a bunch of research before purchasing the gun. I am aware of this issue and only put one drop of oil on my propane tank before installing the nozzle. I highly doubt my bucking is swelling when I have only put 4 or 5 magazines through the gun. Would that cause double feeding anyways? a BB always fires, none ever get stuck in the barrel, just double fed for some reason.

I am going to try some BB Bastards tomorrow and hope it solves the problem.

Do you do this everytime you load up a mag? Because with the MP7 (and some other KWA guns) you tend to not have to oil the propane for about 7-10 refills, rather than the traditional every couple of mags.

djKail April 20th, 2012 20:01

No, I was planning on placing one drop ever 8 - 10 Magazine fills?

Another thing I thought of...is could the magazine being low on gas cause this issue? I can get a few reloads on one fill. Maybe I should charge the magazine fully with propane after each reload?

Thanks for the tips and information. Really great community here. Appreciate it!

Fuzzy April 20th, 2012 20:09

Check the oring on the nozzle. If it is dry, the nozzle may not be retracting into the bolt carrier properly. It could cause a misalignment of the nozzle when the bolt carrier returns to battery.

Danke April 20th, 2012 20:28

Quote:

Originally Posted by djKail (Post 1642095)
I did a bunch of research before purchasing the gun. I am aware of this issue and only put one drop of oil on my propane tank before installing the nozzle. I highly doubt my bucking is swelling when I have only put 4 or 5 magazines through the gun. Would that cause double feeding anyways? a BB always fires, none ever get stuck in the barrel, just double fed for some reason.

I am going to try some BB Bastards tomorrow and hope it solves the problem.

Most likely the action is cycling but the BB is not firing. When you get a few BBs jammed in the chamber one will be kicked out of the muzzle when another feeds.

Have you wound your hopup all the way off?

In warm weather you can get a few mags from each fill. Are you sure the magazine is fully charged with gas?

djKail April 20th, 2012 21:37

Yes, The hop up is dialed all the way off. Because I was running out of things to do I dialed it up by a few notches but it has no effect. I am pretty sure the Mags are filled all the way as I am pretty familiar with GBB guns.

Again, the gun shoots a BB every time I pull the trigger. Nothing is getting stuck in the barrel nor is the nozzle failing to chamber a BB. All that seems to be happening from my oobservations and testing is the rounds are being double fed 2-3 times for every 10 rounds fired.


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