Broken m4 upper receiver tabs

[keyserSOZE]

someone had asked me to fix up his gun, but didnt really want to spend much much into getting a metal body. So I came up with a simple solution.

 

 

Basically, a small hole is drilled from one end of the receiver into and through the gearbox' upper rail and through the other side of the gun. Then a pin is placed through the hole and that holds the upper receiver down.

 

First find a pin that you could use. I used one from a rear sight pin I had no use for. Then just drill with an appropriately sized drill bit. I suggest making the fit of the pin really tight.

 

hope you cheapskates found this useful.

[Outlaw of Torn]

Thats a good idea. May come in useful when my reciver tabs break (crummy plastic....*grumble*).

[Hissing_Sid]

Very impressive.

 

Much better than using a couple of cable-ties.

[Sale]

Outlaw of torn: I would do this mod to a plastic receiver even before they break. Consider what "broken tabs, fixed it" will sound like compared to "flawless receiver, reinforced against breaking tabs" if you want to sell your gun or brag about it.

 

-Sale

[Hissing_Sid]

Hmmm...

 

From what I gather, most people break their tabs when they "slam" the receiver halves together and get the tab caught on the side of the gearbox or when they don't close the receiver correctly and then try to hammer the pin through the hole.

 

In that case, fitting the new pin wouldn't do you any good.

 

Must admit, I honestly haven't much experience of this. Most of the people at my site aren't armalite fans and those that are have gone for metal guns.

My own experience of totally broken tabs is limited to one case where, sure enough, an over-zealous kid slammed the receiver closed and the tabs exploded in a flurry of plastic shrapnel!

 

I have seen a couple of receivers with cracked tabs but it's never clear if it's purely due to stress or if it's due to damage from inserting the pins incorrectly.

 

This is pure speculation but it does explain why some people (probably those who are careful with assembly) swear the tabs aren't a problem and yet most people assume they're a timebomb.

[Aod]

i'm not sure i'd trust to putting all the stress of holding the front receiver up with the Gearbox, i mean, if its out of alignment with the motor, untold damage to the pinion gear, bevel gear and maybe even motor could be caused?

[keyserSOZE]

i'm not sure i'd trust to putting all the stress of holding the front receiver up with the Gearbox, i mean, if its out of alignment with the motor, untold damage to the pinion gear, bevel gear and maybe even motor could be caused?

<{POST_SNAPBACK}>

 

 

even in stock form, the receiver is already held down by the gearbox. so there is really nothing new here.

[Hissing_Sid]

Nah.

 

The worst thing that could happen is the hop-up will leak air and the gun will lose power slightly.

 

The only thing that could happen is the hole in the receiver will stretch and the receiver will become loose (causing the air-leak as above).

 

Even if this happens you could always drill the hole slightly bigger and then fit a bigger pin.

Alternatively, you could always drill a totally new hole.

Either way, you'll be extending the lifespan of the receiver by months or even years.

[keyserSOZE]

here's another photo for reference.

 

[Ghost_Rider]

That's a really good idea..... +1

[The Chef]

nice mod...

 

its probably one of those little things that all Marui owners should do even before the event of the tabs breaking. Nothing like making things ultra safe.

 

for info, the tabs on my marui broke due to the stress of having a Marui 203 on the barrel. The resulting flex when cocking the 203 stressed the tabs and caused one to break.

No taking the reciever apart was involved.

[powelly]

That is a great idea have a +1!! one of my tabs broke on the day i had the gun! christmas day!!!Im gonna do this right now! does anyone know know where to get the stock hop-up set from cuz thatt also broke at christmas, and im losing power cuz of it!