WA-system M4 GBBR builds

Discussion of GBB (gas blowback) replicas.

WA-system M4 GBBR builds

Postby Mr. Technicality » Wed Jun 28, 2017 10:54 pm

Hi folks, been out of the airsoft world for a while but I'm back to work on this build. Wish I'd known sooner what a money pit the WA-system M4's can be but it's been fun tinkering with it. Anyone else out there with a WA-system build? What worked? What didn't work?

The journey:
Mine started out life as a King Arms. Just about the cheapest GBBR I could find. Back then the sticker price was $335. The loading nozzle and hopup arm both failed in rapid succession over the course of one game. Experimented with an Iron Airsoft nozzle, but it didn't fit right. Ended up breaking the locking plate. Started buying RA-Tech parts. Ate through a Prometheus purple bucking over the course of its second game. Three of four magazines held gas at that point. After storage for 6 years, 0/4 (What would one expect?) Swapped out for GHK CO2 magazines. Broke the bolt carrier. Upgraded to steel bolt carrier... and nothing else broke immediately. I was able to get it dialed in to under 330 fps for indoors.

The result:
The entire lower receiver, upper shell, and inner and outer barrels are original King Arms. The bolt carrier is made of steel by RA-Tech. The loading nozzle, bolt/NPAS, and locking plate are all aluminum (also RA-Tech). It's got an aluminum hop chamber from Matrix/5KU that keeps it compatible with AEG barrels. And I'm determined that this Madbull shark bucking will not become food. Magazines are GHK, powered by 12g CO2 canisters. Externals feature licensed Daniel Defense rail, real Magpul rail covers and grips, knockoff sights and stock, beautifully trademarked Chinese Trijicon non-magnifying red dot, ugly but necessary scope defender, black birdcage flash hider, and a QD sling mount. So we're probably up over $1000 with just the current parts and three magazines.

https://www.dropbox.com/s/s5fgdwixns8onld/2017-06-27%2021.27.05.jpg?dl=0
https://www.dropbox.com/s/zcmc2k5gclsnu2d/2017-06-27%2021.28.11.jpg?dl=0
https://www.dropbox.com/s/mj1ook3lidf69em/2017-06-27%2021.29.46.jpg?dl=0
https://www.dropbox.com/s/t737xsd30oc59ac/2017-06-27%2021.30.33.jpg?dl=0
I'm a "fair weather" airsofter. I only play in the pouring rain, freezing cold, or broiling heat.
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Mr. Technicality
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