New M4 Upper receiver

[Jolly15]

I own a CA Metal sportline M4 and was wondering, can I build another upper receiver for it? So I can have one with a 14 in and one with a 10 inch barrel? I've been doing research on it but can't seem to find anything.

Any help is appreciated greatly!

[Gigueand]

I own a CA Metal sportline M4 and was wondering, can I build another upper receiver for it? So I can have one with a 14 in and one with a 10 inch barrel? I've been doing research on it but can't seem to find anything.

Any help is appreciated greatly!

 

 

Sure, all you need to build a separate upper is a separate upper receiver. I myself have a CA M15A4 with spare M4A1 and M16A2 style uppers. The M16A2 upper has the 20" barrel assembly on it, and the M4A1 upper has the standard 14.5" barrel assembly attached. Because the gun is rear-wired, I can slide off one receiver and barrel assembly and slide on the other.

 

There are a couple of things you can do.

 

You could either:

 

1. Buy a 10.5" barrel assembly, unscrew the 14.5" barrel assembly from your receiver and attach the 10.5" to it as a replacement

2. Buy a 10.5" barrel assembly and a spare upper receiver. Attach the 10.5" barrel assembly to the spare upper receiver and swap the whole thing with your old 14.5" barrel assembly and receiver.

 

For either option you'll probably want an AR15 armorer's wrench... but that it up to you.

 

You'll probably want to buy the correct length inner barrel and a new hop-up unit to go along with it. That way the swap can be made really quickly and easily.

[Jolly15]

What upper receiver would work? I've found a G&P Upper and could that work, probably with some work on it?