No problem. Glad my ramblings helped someone.
I have am 8 foot work bench strictly for building at this point. I love the entire building process to the point of being obsessive..and I comparison shop and dig through data on A LOT of parts when I buy. Ive repeated the above process each time to figure out what I want/need.
I probably failed to cover handguards sufficiently. If you are not buying a pre-built upper..look for handguards that have some newer form of mounting/clamping mechanism. Older styles requiring timing a barrel nut to line up with the gas tube by tightening/loosening the nut until the holes lined up with the fixed position mounting holes on the outer area of the rail. This is a pain in the ass. Even worse are the YHM style designs where you're basically twisting a collar onto the barrel nut while simultaneously twisting the handguard on in the opposite direction, and hoping the top rail lines up with the receiver at the end.
The wedge/clamp style locks as youve seen on BCM, Aero, Midwest Industries, Hodge, Zev, Triarc, etc. are all better methods of lockup. Geissele ones are expensive but good too.
Also.. consider the shape of the handguard and the intended use. quad rails look cool but suck to use (cheese graters basically) and add extra weight.
A rail with TOO many lighting cuts and similar will be less durable and will vent heat into your hand.
If you dont run a "low profile/slim" style gas block some of the smaller ID rails can have problems clearing your gas block...
Also..when it comes to choosing the length of the handguard in relation to the barrel..go with at least a half inch less than the length of your barrel, and if you go with one thats shorter (ie a 12" handguard on a 13.5" barrel), make sure your gas tube and gas block will be covered.
