I already knew that this exact part would break soon enough, but I was just getting ready to field my seemingly complete AK74 GBBR for the very first time in a matter of days and was incredibly hyped for gaming it.
That dream of fielding a GBB AK is so close… yet so far.
I was experiencing major FPS loss (fluctuating between 280-350) which led me to wonder if I had an air leak somewhere… lo and behold, chunks of my hop chamber were breaking off near the rear of the unit, where the lip of the GHK bucking interfaces with the loading nozzle. No big surprise here though – practically every 2011+ GHK AK user reports the hop up chambers breaking. Mine has since broken a second chunk off and began to split open after I reassembled everything to check by chrono if this was in fact the case. I was intending to test a prototype A Plus bucking without a lip that was sent to my friend and coworker Joseph “CYC” from his buddy @ A Plus Studios – no lip may mean no lip to fold inwards or outwards and cause a leak. But then another chunk fell out of my hop up chamber and I’ve decided to shelf the whole gun until I get my hands on an enhanced replacement.
Oh well – at least this is the ONLY well-documented, repeated failure with the GHK AK platform to date. Edit: Samoon advises against modifying feed lips (as recommended on GGI forums) to be a little wider to aid in feeding on full auto, as this is more likely to cause double feeds and jams, which in turn will likely cause a BB to lodge between loading nozzle and hop up chamber, causing the chamber to break – good to know now that I’ve already done everything all wrong, according to Samoon’s other articles. Good news is that its easily fixed with aftermarket part – of which there are multiple manufacturers and lots of availability. I think I’m unlikely to have most of the sporadic issues that a few users have reported… or at least, here’s hoping that’s the case. Just another excuse to buy more parts, I guess; no complaints here.
On a good note, I discovered why my GHK shoots so straight and far – the gray coloured bucking has an extended patch of similar length and width to the Maple Leaf (increased compatibility with most AEG barrel windows), yet smooth surface like the A Plus Gen 2 or earlier buckings (R Hop reminiscent performance). I’m going to throw that into an AEG and see how it shoots while I’m waiting for upgrade chamber part(s) to arrive. Edit: caused jamming issues and double feeds (using same ammo I’ve previously confirmed to work fine in this gun) in my King Arms M4A1 with G&P hop up chamber Deep Fire shell and Guarder M16 nozzle. Unfortunately, the adjuster cushion seems to be cut too short – its a solid round rubber nub, but if it was a little wider I would think it would fit the hop window in the chamber a little bit better. May replace the whole system with an A Plus barrel/hop kit after all as the dial adjustment for the hop up is much harder to get at than I had initially thought – that being said, the A Plus adjustment is done via hex key which could be potentially quite a bit more annoying.
Also, the hop chamber design is really easy to work with – GBB allows for quick field strip to remove big components that would otherwise make accessing the hop up chamber incredibly difficult in an AEG: top cover, recoil spring assembly, bolt carrier. Way easier than any M4 GBBR design is to take apart and clean the bucking and barrel – makes my life much, much easier for maintenance.