I had a chance to pick up a BNIB A&K M4 CQB recently and thought I'd share my thoughts on the gun since these low end AEG's are all the rage these days (and all that's "readily" available).
It comes packed in a sturdy styrofoam & cardboard box, containing the gun, metal hicap, unjamming/cleaning rod, a bag of 0,20g bb's, vertical foregrip, a small phillips screwdriver, hopup adjustment tool and manual. Battery & charger are not included. It came with the muzzle brake painted blaze orange, the brake has been removed in the picture to have the paint removed and repainted. Circa 1850 brand stripper worked great btw.
The gun has no trades and is simply marked with the makers "trades". The body is plastic and tabbed like to previous M4 version by TM, not the "New Type" version with reinforced tabs, etc. I expect the tabs to break in short order, like the older TM ones did. The top rail on the upper is metal and is bolted on with allen keys. I chronoed the gun prior to disassembly and it shot a respectable 310 fps with 0.20g bb's. Chronoing was done through a calibrated F1 Shooting Chrony.
The front sight is a standard Armalite triangular type (nothing special) the BUIS is a bit on the crude side for finish but is click adjustable for windage and and elevation and has a flip up sight for longer ranges.
The RIS is metal with rails top, bottom and both side and has covers for the left and right sides. Pretty solid affair, but again, nothing special. The covers provided are quite loose as well. The outer barrel is one piece metal and while no wobble was present (yet) it did twist slightly. The fake gas tube had a fair bit of surface rust. I could not get the RIS off and the Delta ring did not move.
After disassembling the lower and pulling the gearbox this is what you see:
Not overly pretty is it? It's pretty crudely casted and has nylon bushings. Oddly for a gun with a 10" or so barrel, the cylinder isn't ported like it usually would be.
A non-reinforced gearbox. On closer inspection, steel gears and almost no lube:
Seriously, if there was any less lube, I'd say there was none. Shimming was ok, not too much slop. There is a bit of cardboard stuck to the antireversal latch. There's also a lot of what looks like small metal filings all over, though I could find no evidence of any binding or burrs.
The upper end of the gearbox:
Odd, the small tightly wound spring was stuck in the front of the piston. I guess to increase the spring tension and to add a bit of slip like a ball bearing piston head. And no, the head isn't a ball bearing type. Although it is well ported.
The cylinder head sucks. The nozzle is stupidly loose. This will mean the loss of a lot of fps. Notice how the nozzle points down instead of straight out. This will probably break off in short order.
Another point of air loss is the two part hopup chamber. It works, but is quite inefficient.
Overall, it's a cheap copy of a TM M4 with a decent metal RIS. While servicable and inexpensive (good for new/beginner player), I wouldn't expect the tabs to last too long before breaking and I don't know how long to expect the gearbox to last before breaking. It could last as long as a stock TM or longer or it could go it's first game.
While I won't say don't buy one (unlike the Firepower AK I reviewed a few years ago), I will say, expect to get what you pay for. When you pay about $300-$350 for an M4, don't expect the same quality as a TM costing +$500. But at this price, one could replace the gearbox shell with a reinforced version, replace a few internals and replace the body with a metal one and have a pretty decent gun for the money, especially if one were to shop around and pick up a few used parts.