Removing upper and lower M4 receivers

[Widgit]

Hello guys,

I've got a TM SR16 that at some point has had a CA metal upper receiver put on it to replace the plastic upper which inevitably wears out. This has been working fine until I've come to try and remove the upper to get at the gear box.

The upper will slide forward an inch or two but the catch and not go any more forward. Upon closer inspection it appears that the moulding on the metal is snagging on the plastic magazine feed. I've got as far as trying to get a screw driver in the ejection port and remove one screw from the feed, but this isn't going to work as I can't get to the other side.

I can't work out how this receiver ever went on, yet alone how to get it off. If anyone could help you'd help me out a hell of a lot!

Cheers!

[johnnyj]

Re: Removing upper and lower M4 receivers

does the ca upper have pins at the back ? most tm's you just remove the rear pin and then is will open up

[Widgit]

Re: Removing upper and lower M4 receivers

It's not got any tabs, it just has a lip that sits into the lower receiver. I've removed both of the pins and can slide it forward, but no luck. The metal has no give in it at all to slide it forward around the gearbox and off of the lower.

[johnnyj]

Re: Removing upper and lower M4 receivers

1 or 2 part hop unit ?

[Johnno]

Re: Removing upper and lower M4 receivers

On the G & G you have to pull the Charging Handle back slightly and hold it steady while sliding the Upper Receiver off, not sure if your's is the same?

[Widgit]

Re: Removing upper and lower M4 receivers

It's a 2 piece hop unit. The top part of the hop attached to the barrel can move away from the gearbox, but the bottom part, which is screwed into the lower receiver is where the upper snags on. Is there a top secret trick to getting around the lower half of the hop?

[cannon_fodder]

Re: Removing upper and lower M4 receivers

I've had this before with a TM M4 modified to a 1 piece standard hop.

To remove the upper receiver I had to remove the stock and motor/pistol grip and the gearbox pin and the mag catch. This allowed the gearbox to move in the lower receiver and free up the upper. It turned out with the mods the gearbox nozzle prevented the receiver from splitting

[johnnyj]

Re: Removing upper and lower M4 receivers

this gun should break like the standard early tm's , you will have to pivet the gun on the front pin .
So pull the upper forward just a little so the lip is clear and the open the gun up like you would the tm/real steel m4 trying to keep the front together ( putting the front pin back in if you can to help )

[Widgit]

Re: Removing upper and lower M4 receivers

Thank you for all your help everyone!

cannon_fodder was right, having removed the best part of the lower end of the gearbox and receiver I could finally nudge the whole gearbox down and slide the upper off.

It's a real pain in the ass to get at. Now it's done I can finally get at the hop etc. A bit frustrating to have to strip the whole gun just to get the hop out!

Ah well. Thanks again!