Madbull upper receiver threads?

[MooseHead92]

Hey ASC,

I'm doing a Mk18 mod0 CQBR setup for a friend. His primary is currently an ICS CXP 08 with a Madbull Double Star Corp body (link: http://www.airsoftgi.com/product_inf...oducts_id=6254).

I'm not familiar with the CXP 08's RIS mounting system.
As far as my educated guess goes:
1) ICS uses imperial threading on the upper receivers and barrel nuts.
2) G&P also uses imperial threads on their upper receivers & nuts.
3) My Madbull Spike's 9" RIS fit perfectly out-of-the-box on my G&P body.
4) This guy's body is Madbull.
5) His CXP front end fitted fine on his Madbull body

:. Therefore, if Madbull barrel nuts fit G&P uppers, G&P delta rings should fit on his Madbull upper.

I do not want to proceed further until I get clearer info. I've looked up Madbull receiver threads but found nothing. If anyone here knows, please help me out!

Cheers,
Moose

[HKGhost]

Madbull uses Metric threading. The reason for their rails fitting on Metric and Imperial is it's deeper and larger than the intended threads. You'll notice it's kinda loose when screwing on the barrel nut, but not after it's tight.