Wow, love the diversity of builds here—super clean setups! 
I’m still fairly new to the gel blaster scene but slowly diving deeper. Curious about those nylon receivers like the RX AK-style one—how’s the durability holding up over time compared to something like Jinming or Wells receivers?
Also wondering: anyone have experience tuning these builds for CQB-style indoor play? I’m trying to keep my setup compact but still decent on performance. Appreciate any tips or build insights!
Hey there mate, glad to see you joining the circus here 
Would suggest heading over to the “Introduce Yourself” topic and telling us a little bit about yourself. 
Welcome to the show man!
Is the RX AK in question a newer one?
I haven’t had an RX across my bench in years, Aussies lost faith in them quickly before popularity of gel blasters rose in the rest of the world and we haven’t had any of the newer recent models here, which means I can’t speak to them as the might have improved.
They were not reliable performers until the heavy blowback was disabled, which was sort of their selling point, so you were better off getting any other brand. Also they were loaded with lots of proprietary parts so you were sort stuck with the same gear set, all you could do was change the motor, upgrade seals and spring.
But they might have improved, all my information on the RX is very dated, it’s been maybe 5 years since I touched one!
As for setting up for CQB, usually there are two main factors for a good CQB blaster.
A good reliable quick semi auto trigger response, and a short trigger travel/more sensitive trigger.
Fps and rps matters less in CQB, and usually any gains is a bi-product of getting faster response time.
High speed gears like 13 or 12:1, and hi torque motors will improve the response time without increasing the rps too much.
And an ETU /“mosfet” will improve the trigger travel and semi auto reliability and consistency.
RX has definitely slid off the map in terms of AK’s. The top two brands are AKA (Alpha King) or VS, at least in China. Those two are pretty solid but comes with a higher price tag. You get what you pay for I guess.
Oh and welcome to the community!
I had a few different AK’s, including the RX and Alpha King models.
The RiXiang was nicer than the JinMing or CYMA AK’s at the time, but those Alpha King versions were definitely the very best out of anything else at the time. 
I always thought the RX AKM47 was a little underated.
I had one, ripped out the BBU, darkened up the faux wood furniture and didn’t mind it at all. 
Oh yeah, definitely nothing wrong with the RX, they were a very nice AK compared to anything else.
But when the Alpha King arrived, it was just that much better in details and build quality.