Just on a side-note, airsoft GI is probably one of the best airsoft retailers I have come across. I've only had 1 problem with them, they forgot to include something in an order, but when I called and told them about it, they over-nighted it to me with no extra charge.
Edit: JG guns have gone up in their reliability the past few years, as have the CYMA brands as well(atleast on their AK line).
also, if you're planning on making an AR or a BR I would suggest using a FAMAS as a base (Not sure if anyone mentioned modding one in the thread, thought I saw something). The bullpup design of the FAMAS would make it a fairly simple body mod, no mucking with the internals.
Edit 2: Forgot to answer the "can it work?" question. Yes it would work, you just have to mod it. airsofters have been modding guns since the sport first appeared.
Once you get this working, this is going to be epic. Good luck man hope everything goes as planed. Are you actually going to try to use the gun in real airsoft matches or do you just want a working Sniper for the hell of it? Lol Either way it will be badass.
ryandaw: If he had $850 to spend he can buy the second gun I posted to avoid the bolt all together. He would just have to fill in the stock and turn the barrel into a floating barrel.It shouldn't be all too hard but it would tear my heart to hack away at that gun.
i like that airsoft gun he's getting i use to have it and it worked great. If i try making the sniper rifle i might get a CO2 airsoft rifle one from this place near me. Also the tippman A5 can be customized to look like the berret 50 cal for about $450 all together then you could go from there http://www.opsgear.com/Tippmann-A5-Shroud-M107-p/og-shroud-m107-a5.htm