The A&K SPR MK12 MOD0 is a very pretty gun, for certain. The externals are what you should buy it for; expect to modify or replace the barrel and hop-up. Ergonomically, it's pleasant, but the performance was disappointing. It's also missing some accessories that were included with the previous version of the gun.
Overall this feels like a gun that should be substantially cheaper than the last version, but it's not.
-It's an unusual M16 variant for under $300.
-Battery access is easy: just slide the locking tab on the stock downwards and let the door fall open.
-Monolithic rail can fit pretty much any optic, even a NV unit and scope if you can afford it.
-The flip-up sights are addictive to play with.
-Feels real; nice and heavy, but fairly well balanced even so.
-The finish on the gun's externals is even and attractive.
-Significant rate of fire; although I don't use it, it's around 14-15 rounds per second.
-Comes with a hi-cap M4-styled curved mag, rather than the VN-style midcap that's more commonly seen with the rifle.
-No battery, for those of you who'd like one. The other version DID include a battery and charger
-Really, no major steel parts. Everything's aluminum or unidentified pot metal.
-Inner barrel is only about 14 inches, while the outer barrel is 16. It just bugs me.
-Has poorer accuracy than my CYMA 048 (my typical benchmark).
-Missing the SPR flash hider that the other version also came with, instead has a cruddy A4 plastic birdcage.
-The hop-up is ineffective; even when all the way up, the BBs were still falling at around 120 feet.