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?

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.

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.

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?

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

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

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

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.

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.

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!

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.

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?

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.