B&T MP5 issue with feeding

[Bobbybrown]

Hi all 

Just got my first battery MP5 yesterday, only mark I can see on it is “B&T”.

issue I’m having is it doesn’t feed, if I drop the BB down the barrel it’ll shoot it out, it doesn’t take them from the mag despite the mag appearing to work as it should.

 

I’ve stripped it down and the gearbox(?) that connects to the hop up unit and the barrel appears to maybe be the issue.

 

I am assuming the small pipe on the end of the gearbox that connects to the hop up is supposed to go in and out when it shoots, to allow the next BB to load, this isn’t happening. 

Is this supposed to move in and out when being fired? And if so, any recommendations what I can do to repair it so it does? I haven’t fully stripped an AEG before so it’s new territory for me, but if there is something specific you need to be able to see in order to help I’ll do my best to get to that part and photograph it.

for now, this is the “pipe” I’m talking about.

 

many thanks.

[Nick G]

The bit circled in blue is the loading nozzle and it should indeed move back and forth as the gearbox cycles.  Is the gun new ? if so probably easiest to send it back. If you want to fix it yourself though you are going to have to open up the gearbox as the nozzle is moved by the tappet plate which is internal. May have popped off or there may be a damaged part.

 

If you havn't opened a gearbox before then get yourself onto youtube and watch a few videos first, also watch a coupke about stripping down an MP5 as they are different to an M4 and indeed there are several methods of strip down for MP5's so have a hunt for a video that matches your model.

[Floperator]

Should those wires be sitting there in the magwell between the mag and nozzle?

Did you buy this new or 2nd hand?

[colinjallen]

The nozzle should move, as it should be connected to the tappet plate.

Where did you buy it?  From a shop or from a private seller?

Edited July 19, 2022 by colinjallen

[Bobbybrown]

From a private seller, wasn’t able to check it properly but dry fired it and it was fine, wasn’t in a position to be able to cycle bbs through it sadly. Regretting that now.

I’ve had it in bits today and put it back together to make sure it’s nothing obvious. Still the same. I think I’ll need to get the gearbox open as you guys have said and see what I can see in there.

Would it be easier to replace the gearbox? I suppose then the question of suitable replacements pops up.

3 hours ago, Floperator said:

Should those wires be sitting there in the magwell between the mag and nozzle?

Did you buy this new or 2nd hand?

I had started stripping it at the point I took the photo so I think that’s why they are so obvious in the photo as I had moved things around 

[colinjallen]

10 hours ago, Bobbybrown said:

From a private seller, wasn’t able to check it properly but dry fired it and it was fine, wasn’t in a position to be able to cycle bbs through it sadly. Regretting that now.

I’ve had it in bits today and put it back together to make sure it’s nothing obvious. Still the same. I think I’ll need to get the gearbox open as you guys have said and see what I can see in there.

Would it be easier to replace the gearbox? I suppose then the question of suitable replacements pops up.

I had started stripping it at the point I took the photo so I think that’s why they are so obvious in the photo as I had moved things around 

There are lots of videos that will show you how to open and work on a gearbox; use this as a learning experience.  That nozzle should be attached to a long piece of plastic inside the gearbox; this is called the tappet plate and its job is to move the nozzle backwards and forwards.

Where are you based?

[Bobbybrown]

I’m in Tamworth.

To be honest I’ve wanted to strip one down for some time, I have other aegs but I’ve never taken one apart so I quite enjoyed taking it all to bits and reassembling, sure I’ll enjoy it even more if it works afterwards 😁

[Bobbybrown]

We have progress!

gearbox opened and I’ve found this broken piece. The only details on the gear is CA-SL.

Can anyone tell me the name of this gear so I can try to find a replacement please?

 

Thankyou 

 

I think it might be called the sector gear but an online search doesn’t show any exactly the same, are they all the same size? 

Edited July 20, 2022 by Bobbybrown

[colinjallen]

40 minutes ago, Bobbybrown said:

We have progress!

gearbox opened and I’ve found this broken piece. The only details on the gear is CA-SL.

Can anyone tell me the name of this gear so I can try to find a replacement please?

 

Thankyou 

 

I think it might be called the sector gear but an online search doesn’t show any exactly the same, are they all the same size? 

That would explain it!  That piece pushes the tappet plate back, allowing a BB to feed.

It is indeed the sector gear, but you would probably be best advised to buy a whole new 16:1 gearset from someone like AK2M4 (allegedly, other purveyors of airsoft bits and pieces do exist), along with a delayer chip to ensure that the tappet plate stays back long enough.

Whatever you do, you are going to have to do some shimming to ensure that the gears are spaced properly.  There are some very good guides to this online.

Edited July 20, 2022 by colinjallen

[Bobbybrown]

3 hours ago, colinjallen said:

That would explain it!  That piece pushes the tappet plate back, allowing a BB to feed.

It is indeed the sector gear, but you would probably be best advised to buy a whole new 16:1 gearset from someone like AK2M4 (allegedly, other purveyors of airsoft bits and pieces do exist), along with a delayer chip to ensure that the tappet plate stays back long enough.

Whatever you do, you are going to have to do some shimming to ensure that the gears are spaced properly.  There are some very good guides to this online.

Good, I’m going to need every guide I can find.

also had a look at a drop in replacement but will keep looking. I’ll check out the 16:1 gear sets and see what I can find. Would love to get this thing up and running before I forget how it goes back together 😂
 

Is there a way to know the ratio of the gears in there at the moment? Are they likely to be 16:1 or could they be some other ratio.

Off to YouTube to check out videos on shimming 

Edited July 20, 2022 by Bobbybrown

[colinjallen]

They are most likely 18:1; you can check the ratio by counting the teeth on each one and working out the ratio that way.

[Lozart]

12 hours ago, Bobbybrown said:

Is there a way to know the ratio of the gears in there at the moment? Are they likely to be 16:1 or could they be some other ratio.

Off to YouTube to check out videos on shimming 

 

10 hours ago, colinjallen said:

They are most likely 18:1; you can check the ratio by counting the teeth on each one and working out the ratio that way.

 

As above, standard gear ratios are usually 18:1. 16:1 will make your gun run faster (not loads more but even so). These are very good https://www.ak2m4.co.uk/internal-parts/gears/zci-gear-set-advanced-18-1 these are at the very least better than the ones that are in there right now https://www.ak2m4.co.uk/internal-parts/gears/shs-18-gearset

Set of shims https://www.ak2m4.co.uk/zci-shim-set?search=shim (do your research on YouTube and TAKE. YOUR. TIME.)

Get some decent lube and clean the gearbox out while you're at it.

Gear lube: https://www.amazon.co.uk/Abbey-Shotgun-Airsoft-Spring-Molybdenum/dp/B071FYQGLJ/ref=pd_lpo_3?pd_rd_i=B071FYQGLJ&psc=1

Seals and piston rings etc https://www.amazon.co.uk/Abbey-Silicone-Grease-Gun-Maintenance/dp/B00LHTIH7G

Degreaser (for cleaning) https://www.halfords.com/motoring/engine-oils-and-fluids/engine-cleaner-and-degreaser/halfords-engine-and-parts-degreaser-500ml-621525.html

[Bobbybrown]

Tremendous! Thankyou for that and the links, that’s super helpful.

I’ll have a look at those and get some orders in 

[Bobbybrown]

Gearset and shims should arrive today so fingers crossed I can figure it out. I’ll update when I’ve got some news 

[Bobbybrown]

Having some trouble getting the gearbox back together, given up for tonight will try again tomorrow. The smaller piece on the bottom left (think it’s a stop for the wrong way?) has moved so I need to figure out how it was in the first place.

 

Will battle on tomorrow, asked a friend who’s had airsoft in the past if he knew how to do it as he’s the only person in Tamworth that I know, that has airsoft but alas he hasn’t got a clue! Shame 😂

[Shamal]

I think you mean the anti reversal latch? Got a fine spring on it? 

 

Have a look at some pics on Google. That will show you the orientation of it.

It can be a pain to get it to stay in place. 

Good luck.👍

 

[Bobbybrown]

20 minutes ago, Shamal said:

I think you mean the anti reversal latch? Got a fine spring on it? 

 

Have a look at some pics on Google. That will show you the orientation of it.

It can be a pain to get it to stay in place. 

Good luck.👍

 

That’s the one 

[Shamal]

2 minutes ago, Bobbybrown said:

That’s the one 

Yeah. Just Google it mate.

I think you can use something really thin like feeler blades to hold it down while you offer up the top half of shell.

🤞

Regards 

[Speedbird_666]

A strong magnet usually works to hold the Anti-Reveral latch in place.

 

Put the magnet on the underside of the left receiver shell (the side where the gears are placed when assembling) over the hole where you insert the ARL. Makes life a lot easier.

[Bobbybrown]

Thanks for the advise guys. Really appreciate the help 

[colinjallen]

On 26/07/2022 at 20:41, Speedbird_666 said:

A strong magnet usually works to hold the Anti-Reveral latch in place.

 

Put the magnet on the underside of the left receiver shell (the side where the gears are placed when assembling) over the hole where you insert the ARL. Makes life a lot easier.

Alternatively, you can buy these wonderful things: https://www.thecageairsoft.co.uk/airtech-studios-gik-gearbox-installation-kit-aeg/

[Spencer6277]

Yes I was just going to recommend them clips. Very useful on a V2 box as the trigger likes to pop out aswell.

 

Yea as said above, just take your time on the gearbox. There is no rush. You will only end up having to strip the entire gun again if a problem arises. Been there so many times 

 

Just double check with the new sector gear and delay chip that the tappet plate pulls back far enough to load a BB and far enough forward to seal against the bucking.

I find MP5 to have small tolerances when it comes to this. If your running a full stroke then timing will not be an issue. 

 

There are guides online that walk you through this. Might be related to Short stroking but still relevant information

[Bobbybrown]

So I’ve been trying to do this for a couple of weeks now and failing. One part goes in then another pops out. Nothing feels as free moving as I would expect it to, almost like it binds but that will due to how I’m doing it I expect.

With this in mind, and that I’m close to going mad with it I’ve messaged the only person on the forum that I know is local to me to see if he can help, if not I’ll have to look for someone I can post it out to so they can put it together properly in return for some money.

I would love to get this mp5 up and running soon, it’s the one gun I’ve always wanted and it’s my second one, the first was a well g55 gas one that had a leaky mag then broke a piece inside, so I’ve never been able to use it properly. Hopefully this one will be different once the gearbox is sorted 😁

[Bobbybrown]

No luck so far 😫

Is anyone able and willing to put this gearbox together for me? I can send it to you how it is with the new shim pack I have, just let me know what you want for doing it.

[Mels]

maybe an idea? If not I'm close to you and don't mind having a look.