What I like best about the Colt Le6920 that they want your balls for has allot to do about the weight. Weighing in at 5.69lbs. I would like to build a good quality carbine with a 6 position stock or maybe an ace stock if it saves enough weight. I want it to be a flattop so I could put an Eotech on it. (Eotech not counted in weight). Chromed lined barrel and chamber, single stage trigger. I'd really like to get flip up front and rear sites. Without the carry handle the rifle should be around 5.5lbs. and be built with all solid quality parts and be cheaper then buying a Bushmaster or RRA carbine. Can it be done, with what parts, and how much would it cost.

There are a lot of ways to do it. A pencilweight barrel would be nice (as on a Colt 6520, but that is A2) as would a Clark or Hyperform carbon fiber free float tube (saves something like 4 oz.).

Old school M4 stocks are lighter, you could get an A3 upper with no forward assist, that is a couple ounces. A Young Manufacturing/Les Baer ultralight carrier (available from MSTN--but expensive) would save quite a bit of reciporating weight, but I don't know if that is good for reliability. Never tried one. Ace stocks are pretty light, if you get the right model. Tangodown pistol grips might be ever so slightly lighter than A2--no one has measured one, to my knowledge.

Flip front sights would be heavier, except maybe the models that attach to the barrel instead of the gas block. Then they would weigh about the same, if I may hazard an educated guess. Irons all around really would be lighter!

New-Arguy built a very light carbine a while back. Had a light even and was still very light. You should IM him.