Curious if anyone's ever used an Airsoft GBBR to practice/train? They have some pretty damn realistic ones. I'd imagine a Gas Blowback system would be better than an AEG. Used to have a KWA SR10 and i can't see that being too great. Watcha guys think? Have 3+ acres of open land here with a bunch of trees lining the back of the property, so i'd probably set a few metal targets or something up against the trees. That with a few low cap mags (10rds each i guess) would be cool just to practice acquiring targets and such. Can find one to mock my real AR, perhaps.

Its been done before.  Depending on the model, you may be able to add/use real steel components, like holsters, grips, sights and certain other accessories.  Problem is, stuff like springs are wimpy and weak compared to the real thing, controls may not always work (especially on AEGs) trigger pull is usually pretty substantially different (again AEGs), and dimensions and/or weight are usually off, so they may be too tight or too loose in a holster.  Certainly cheaper and somewhat safer to practice with (still wear at least shooting glasses), but you do need to be aware of the limitations.  If you can get it set up properly like your real firearm, it probably will be somewhat helpful and at the least fun to plink with if you already have it.  Otherwise, depending on how expensive the model you're looking at may be, an extra case or two of ammo might be a better use of funds...

Used to plink at little steel targets and crap when i was younger, which is where the idea came up (Found some BB's stuck in my moms old ass planters :D)
I had a Gas blowback 1911 for the longest time (Recently threw it away, brother 'borrowed' it, and i got it back years later with the springs so worn the slide just flopped around). that i'd also shoot with. Actually got pretty good with both lol. 
Anywho, been a long time so i forget what it was like, and i'd never shot a gas blowback rifle. Obviously not identical to the real thing but as far as practicing something like acquiring a target, aiming and pulling the trigger, i'd imagine itd be a great resource if i could find an inexpensive one locally. Only downside is green gas performs terribly in the cold for obvious reasons (it being a gas). AEG's don't have those issues, and i've fought in many winter war scenarios... lol.