MP5 Metal Front Cocking Tube Slipping Out
 

Recently, I finally spent the cash and bought a mosquito molds RIS unit for my MP5. After quite a bit of grinding with the dremel to get it to position and fit onto the receiver, I was able to assemble to gun again.

The entire front of the gun is pretty heavy now and it is causing the front cocking tube assembly to pull/tilt forward out of the receiver. It really bugs me and every time I hold the gun, it looks like the barrel is bent downward.

1. is there any way to fix it? I installed the RIS unit a few years after I installed the metal recevier/front cocking tube bits, so the part that slides into the receiver may have lost some metal since it was really tight when I initially installed the metal kit.

2. how about crazy gluing it into the receiver? It would probably do a decent job of keeping it from slipping, but is there any way to 'un-crazy' glue it if I ever need to get into the guts and repair anything?

Thanks,
Jerold

A short length of copper pipe should work to reinforce the cocking tube.

can you clarify? I still have the tabs on the front tube. The weight and just the little bit of metal that shaved off from pulling them apart a few times loosened it just enough to enable the slippage.
I just remembered that there is a little copper or brass clip that goes around the inner barrel and has a hole for a screw that screws into the front tube assembly, so there essentially, the front tube won't come off, but there is enough play to cause the front tube to move out of the receiver.

The trouble is that the stock cocking tube assembly is not well attached to the receiver. It just isn't meant to take the weight of the RIS.

Crazy glue will crack quickly and need to be reapplied. Acetone will melt crazy glue quickly... but expect some damage to your gun in the process.

You could take out the cocking handle and slide a copper pipe into the tube assembly for now, but you need to reinforce the joint. A short copper pipe (2 inches) inserted into the joint between the receiver and the gas tube assembly and then secured somehow would probably do the job.
Mind you I'll need to look at my own MP5 to figure out exactly how I would do it.

Do I need to remove the tabs on the front tube assembly before trying the copper tube?

If you get a chance to look at your setup, can you take a few pics so I am not misunderstanding your description. I haven't taken a look at my own gun, so I don't know for sure how the copper tube will fit into the receiver and the front assembly. Just a little confused if I slide the copper tube into the front tube assembly (replacing the area where the cocking handle lives) and then I slide the front passembly into the receiver, wouldn't the copper tube be smaller than the hole in the receiver that it is sliding into?

Sorry for my lack of vision here...

Jerold

The copper tube will need to be small enough to fit inside the gas tube and the hole in the reciever.

If you use a small length of tube you should be able to have it sit just at the joint of the gas tube and the receiver like so:
http://www.geocities.com/darkalman/MP5.jpg

Then its just a matter of reinforcing it in such a way so that the pipe doesn't move. Ideally it should just be a friction fit.

Measure out the inside diameter of your cocking tube and buy about a foot of appropriately sized copper pipe. Then experiment a bit before you have to cut away anything.

If you do things right you should be able to keep a working cocking handle for the gun.

I acquired a junker MP5 last year (well abused, missing parts, etc. got her all fixed up and in pristine shape) and there was nothing in the cocking tube area except for a copper pipe, about 8" long or so, I'd guess 1/4" to 3/8" ID, wrapped with many layers of black electrocution tape. It sat about half way into the body, say about 4" into the body (where the spring and guide normally sit) and 4" into the cocking tube. It was done by the previous owner (said it was a rental gun for many years, and he added the pipe to strengthen the gun to better withstand "noob-abuse".)

Xtreme tactics modifies there MP5's in the same way. The pipe reinforces the structure of the weapon significantly so it can take alot of abuse.

However the process removes the cocking handle. You should be able to add some reinforcement in this manner without losing the look and feel of the gun.

Thanks for that description!

I'm forgetting what the inside of the upper receiver is like, but is it totally empty up in the area of the receiver where the front cocking tube assembly slides into the receiver so I would be able to get a pretty long piece of copper tubing into it?

I highlighted the area on the MP5 image that I'm referring to, but I can't figure out how to insert a photo...

Is there a tutorial somewhere?

off topic:
how come the muzzle on the MP5 A4/A5 attaches to the front sight so crappy, instead of doing it like the MP5K where it threads onto the front sight? Has anyone ever done an aftermarket to make a better front sight/muzzle for the A5?

That set screw is quite dissapointing to me as well.

Threading something like is possible, but not easy.

If and when I lose mine I'll likely drill out the hole and thread it to accept a larger bolt to act as a set screw.

Then again my brother is a metal worker...

You could yes, the only concern I have is do you care about the cocking handle. If not then put in a lengthy piece of pipe, otherwise you will need to shorten it so it only sticks out about 1-2 inches from the reciever end.
Then hopefully the cocking handle and return spring will float inside. You may need to add a stop in the middle of the pipe to prevent the spring from going too far back. A screw will suffice.

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I never had a problem with the muzzle or the set screw, just stick some nail polish or theadlocker on the threads and leave it.

Touché

Locktite is a wonderful thing. Just make sure to use the blue, otherwise you'll never be able to take it off.

Back in the day, I ended up stripping the threads on the front sight for the set screw to secure the muzzle. I ended up just getting a fatter hex head screw and tapping a bigger hole. The muzzle was always a tad bit smaller than the opening in the front sight, so to secure the muzzle with the screw, I tightened it until the top of the muzzle butted up against the underside of the front sight. The metal is so soft that the set screws end up boring holes instead of pressing against the parts.

just wondering if anyone has ever put out an MP5K type sight/muzzle for the A4/5

Sorry, I mis-wrote my question.

Is the uppermost area inside the receiver totally empty so I could possibly place a long length of pipe in the receiver (above the mechbox) and if I want to keep the cocking handle, just leave out 2" out the front of the receiver?

There's alot of space in there but I'm not entire sure.

The cocking handle spring goes a bit into the receiver if I remember correctly. But it should fit inside the hollow copper pipe. I'd have to examine my own MP5 to give you an answer for sure.

Cool!

Thanks for all your help!
I'll just take the plastic parts with me to the hardware store to size up the copper tube.
If I can just figure a way to get my battery to fit into my RIS unit, then I'll be set.

Full stock
Empty LAM module,flash light
Seem to be the most common options

If your lucky you might be able to float a stick battery inside the copper pipe, but I wouldn't hold my breath.

I actually use red and they still come off pretty easily, I think there are two different types of the red, one of them is pretty permanent, the other is like the blue. Just gotta pay attention to the label.

just got home and pulled out the original plastic MP5 body and I understand how the copper pipe can definitely do the trick. I forgot that the tabs were on the receiver and not the front tube, so it actually works out perfect. The copper pipe will stiffen the connectionbetween the 2 parts and the tabs will help to keep the parts aligned properly.

**UPDATE**

I was inspired late tonight to fiddle with all the advice from this post.

I found a piece of copper pipe and pipe cutter in the shed that fit perfectly into my factory plastic front tube. After some test fitting, I could only get about a bit more than 1 inch into the receiver because the top plate peice that spans both sides of the metal receiver doesn't copy the inner contour of the rounded receiver. I didn't want to totally take the gun apart to shave it flush, but it would be possible. That way, you could get about 4-5 inches into the receiver. Funny thing about the cocking handle - and timely. Stupid thing broke off, so I didn't have to take apart the sight to get it out. I can slide an entire 5" into the front tube. It bottoms out at 5" and helps when you jam it into the reciever for final assembly. The pipe totally fits snug into the front tube, so no cocking tube assembly anymore - kinda looks cool with the copper color showing. I couldn't get the pipe into the metal version of the front tube, so I decided to reuse the plastic front tube. It actually doesn't look too bad - I've upgraded everything that can be into metal so a bit of plastic works for me. The inner diameter of the metal tube is a shade smaller than the plastic one. I think that I can hammer it in, but I'll try it later. The plastic tubes works better for the battery and the wires since the metal tube didn't have enough space and the battery had to be jammed into the RIS unit.

Still unhappy with the 3 lug muzzle and front sight assembly. My modified grub/hex screw was just eating into the soft metal of the muzzle and if I screwed on a supressor to the muzzle, the weight of it would just grind the muzzle against the screw till it loosened up. I tried looking for a replacement MP5K front sight on the internet and NO ONE carries any type of replacement front sight for the MP5k. Not to be defeated, I decided to fill the empty space, so I wrapped 100mph tape around the muzzle that goes into the front sight, trim off the excess, cut out the alignment slot and peel off layers until I got a tight fit. Once in, I applied inward pressure and tightened the grub/hex screw up from the bottom of the sight and that sucker feels pretty solid. It actually came out way better than I thought it would.

Thanks for your help again!

No problem, glad it worked out for yah.