MP7 not firing

[jerryliang2k]

I was at FR yesterday (27th, Feb) and I brought my mp7. I have two batteries and charged one of them the night before. When I woke up on the 27th, I took a few shots in the basement and the gun performed flawlessly on auto and single fire.
When I got to FR, I went out to the firing range to adjust the hop and calibrate the laser. After about 20 BBs, the gun's ROF started to decrease dramatically. Perhapse 10 BBs later, the gun just refused to fire. It seemed like the battery just died or something and I figured it was just due to the cold.

Now when I pull the trigger, absolutely nothing happens. No motor wirrs, no clicks, no nothing. The trigger does pull all the way down so its not the safety causing problems. This is true for both single and auto firing modes.

Now, I'm fairly sure all thats broken in the gun is the fuse, but what could have possibly caused that? Cold weather? The gun hasn't been used much and the FR game was supposed to be it's first game. The previous owner never gamed with it either.

any insight would be helpful,

Zi-Xiao

[jerryliang2k]

OK so I got a G&P aimpoint today and replaced the A10 fuse for my MP7A1. So with the new fuse in and a charged battery, I pull the trigger and hear a clicking sound in the reciever. When I let go of the trigger, I hear another clicking sound in the reciever.

After a few trigger pulls, I don't hear the clicking sound anymore but the gun doesn't fire either. I remove the top rail to find that the fuse has once again been broken. The fillament that runs down the legnth of the fuse is severed in the middle. So now I'm sure it wasn't JUST the fuse thats causing prolems.

Something must be causing these fuses to break so easily. I have no idea whats causing these problems.

Help would be greatly appreciated.

thanks,

Zi-Xiao

[jerryliang2k]

I took most of the MP7 apart. If I look down into the reciever, I can see that the second click is accompanied by an electrical spark. Hopefully that means something to someone.

In the mean time, if anyone knows how to remove the mechbox from the MP7, please let me know. I've taken out the stock and rear plate, but the mechbox won't slide out.

Zi-Xiao

[Vince]

I had a similar problem on my M16
I played an outdoor game in the cold, and in my basement it was firing perfectly, avec only a real cap mag, nothing happened. So changed the fuse at home, and heard clicking inside the reciever. The fuse died each time after two pull of the trigger. I finally opened up the GB just to find that I had a gear with missing teeth. I changed it and it now works just fine. I'm quite sure you have the same problem as I had.

[Jayhad]

it is possible that the screws in the top rail have contacted the power wires and they are now arcing. I have seen this in 2 stock mp7s lately, not my onw but team mates

[Razcal]

I had the same problem with my TM M4. It was working just fine then it just stop firing all together. Blew the fuse aswell. I had just completed some work on it so i thought that it was an electrical problem. I took the motor out and hooked it up to the battery, replaced the fuse, and when i pulled the trigger it powered the motor just fine. Not an electrical problem. After some playing around i figured out it was the placement of the motor that was wrong. It was not seated in the (handle) just perfect, which caused it to jam in the mechbox. Motor stops turning, turns into a heater, then blows the fuse. By making small adjustments to the allen key screw at the bottom of the handle i have managed to fix this issue. Been through a couple thousand rounds since with no problems.

Dont know if this is your problem, but i hope this helps.

[Uziguy]

I remember there being a thread on ASC which talked about the MP7 charger "dangerously over charging" the batteries because of the voltage differences between HK and Canadian outlets. Is it possible that your battery is overcharged thus frying your fuses?

.......... just a thought.

[Kos-Mos]

No it is not possible. An overcharged pack will just won't last as long as a well charged one.

I bet on the binding somewhere in the mechbox, since it would cause the motor to constantly drain an extreme amount of power. Also, it would cause the trigger to arc when opening the contact. The tick sound probably comes from the arking both when closing and opening the trigger switch.

[jerryliang2k]

Thanks for th feedback guys. I've heard nightmares about the MP7 mechbox. Having had first hand experience with MP5Ks, I'm not touching the MP7 with a 10 foot pole.

I'm trying to contact my local gunsmiths but haven't got responses (maybe they're scared too ). Anyways, if anyone knows someone whos man enough to take apart an MP7 mechbox apart, please let me know.

As for a mis-aligned motor, I'm not sure if thats possible. MP7 moto isn't in the grip because of the magazine. I think its fixed in the gearbox. But of course I wouldn't know for sure.

Zi-Xiao

[TheYellowDart]

On the top rail, there is a small hole where you can fit an allen key through to adjust the motor position. Not sure if it is your problem, but the motor can be adjusted.

[Jayhad]

Johnnydo has been in my MP7's mechbox several times, he did a great job on it try PMing him

[JohnnyDo]

you have PM

[jerryliang2k]

I've talked to John already and he's been very helpful. I'd like to take a look around for local gunsmiths before sending it off to calgary. So are there any local gunsmiths willing to take a look at my MP7?

Zi-Xiao

[Apoc_]

I sure hope this isn't the same MP7 I just bought, as there was no mention of it not working in the original post....