Re: Help me upgrade my Bushmaster ORC 308 please.
Alright, well, no reply, so I'm going to make some assumptions and we can go from there.
.308 ARs are the best rifle platform on the market right now, if you ask me. I love mine, and plan on owning/building several more. The Orc has a midlength gas system, so if you want an adjustable gas system, you will need to keep that in mind when selecting handguards. You will have to either be able to access the adjustment mechanism through a slot in the handguard, or from the front, in which case they will have to be about 12" or less. I assume, since you got a rifle with a 16" M4 profile barrel, that the goal is to keep this rifle light weight. Since you asked my opinion, I would steer you away from quad rails - they add unnecessary weight to an already heavy platform, and you can hang all the necessary stuff off of a modular handguard with less weight, bulk, and cheese-grater efect. If you have to have a quad rail, get the DD - they're the lightest. JP, VTAC, Apex, Samson, PRI, SWS, and Troy all make good freefloat modular handguards, which is what I would recommend. Most, if not all of those handguards have or can have top rails designed to align with the upper receiver rails.
Your rifle uses the DPMS/Remington/Fulton setup. EVERYTHING from and for those rifles, along with every other "radiused receiver" .308 AR on the market that I am aware of is compatible with yours. A large number of parts from the "slant receiver" SR-25 mag .308 ARs will also work. The Armalite/Noveske stuff is different.
As far as a gas block is concerned, JP has some good setscrew options (I am running one right now). Keep in mind what I said about accessing the set screw with the handguard. My advice would be to run what you have until you have issues. If you have a lot of function issues or primer blowout, it might be a good idea to get an adjustable gas block, because chances are it is over-gassed. Check out Paladin Machine gas blocks - they come highly recommended, and I plan on on replacing mine with one when I get my next barrel, if not sooner.
For an optic, I would highly recommend a 1-4/1-6/1-8 scope. SWFA Super Sniper, Vortex, Burris, Swarovski, IOR, Leupold, Trijicon, S&B, March, and USO all have good options running everywhere from a few hundred to a few thousand dollars.
As for the buffer, what is in there is probably very serviceable. Fulton had a heavy buffer that you could try. Another buffer option is the Enidine hydraulic buffer, but I have heard mixed (mostly positive) reviews on them. They would help with recoil more than a standard buffer, and I liked the one I shot. I've gone back and forth on trying one myself - probably will. Keep in mind, the carbine and rifle buffers for .308 are are different from .223 ARs. I would do this upgrade after you have the rifle setup how you want it, and consider upgrading the buttstock with the buffer and spring to something that would balance the weight a little better. The UBR, ACS, and Vltor E-MOD all work very well on rifles that are more front heavy.
Another upgrade I would STRONGLY recommend is a BCM Gunfighter charging handle.
