building second upper for M4

[ericwilliam]

I'm building a second upper for my CA M15A4 CQB-R

What upper receivers are compatible with the CA lower? (It only uses the single front pin, not the double pin style)

Any help would be great, thanks.

[Stealth]

Single front pin??

AFAIK, all CA's have the double REAR pin.

Only other uppers compatible with the CA lowers are the VLTOR ones by Madbull, they may be discontinued.

[ericwilliam]

mine is taken down the same way as this

(Airsoft) Classic Army M15A4 Disassembly/ M4 Disassembly - YouTube

[Stealth]

Ahh learn something new everyday..

G&P's *may* be compatible with a CA lower, but the tolerances may be off and you'd have to shim the body or use a magic pin. You can try some ACM uppers. The one from asiaairsoft looks awfully similar to CA's upper.

[ericwilliam]

Excellent, I was looking at G&P's, and I dont mind doing some tinkering to get it to fit, whether its some small grinding etc.

thanks!

[Kos-Mos]

Most aftermarket receivers use that method of assembly.

BUT G&Ps are know not to fit with anything else.

Best bet would be a cheap chinese upper. At least it won't cost you an arm if it does not fit, and is easy to resell.

Older CAs had two metal pins extending from the rear of the upper receiver into the lower above the buffer tube. Theses are long gone.

Most new metal body use a lip that slides under the lower receiver at the same place.