2ndovc wrote:And why are all these companies still making those stupid stepped down barrels? Anyone really need the grenade launcher option?
Colt used to sell a "Target Sporter" version that used that very barrel, with the only other change being a ground-off bayonet lug...
As far as a 'company run down', there was a post I think on AR-15.com that went into the details of the various 'lower' manufacturers, and it turned out that almost ALL the lowers are made by about four companies, then marked/labeled for those vendors/retailers (at least as of when the article was written about five years ago). That was enlightening.
I bought one foreign-named lower that needed some hand-filing for stuff like the bolt-lock to fit, but I used it for a Zel bolt-action upper in 338 Lapua, so it didn't need to be precise in those dimensions, as long as it held tight to the upper, and held the trigger-group in place.
Personally, I find CMMG and Bushmaster and DPMS and Colt to all be quite well made, precise, and strong. However, it's like "Reloading Equipment" - most of us try a brand, like it (nearly all of them are good), and then become a strong advocate for that brand, or rarely, get burned by one item, and tell everyone to stay away from that brand forever.
The 18" 0.960" or whatever short/fat barrels seem to ME to be ideal, as they are short enough to not be as heavy as their diameter would otherwise cause, but stiff enough to be very accurate. If using a short/carbine gas system, consider an adjustable gas block, heavier spring or buffer, or even an exposed 'piston' system that vents excess gas, just for less wear, but honestly that may only matter if you are a very high-volume shooter.
Twist rates are debated, but just get the twist that suits the bullet weight you primarily want to use.
I currently have my AR set up with a 16" mid-weight barrel and carry-handle upper with iron old-school sights and suppressor, kept in the safe for urgent varmint duty (we live on a farm), plus these alternative uppers:
- a 18" fat barrel and scoped flat-top upper in 223 for more precise target shooting
a 20" 'bull' barrel that I dislike, as it is a 'Clinton-era' with compensator and way too LOUD (but accurate)
a 16" barrel (trying out several, actually) in 300 AAC Blackout, and suppressor (fun, but ? practical ?)
a 16" barrel in 50 Beowulf (even MORE fun - think semiauto 45-70 in a carbine-sized gun)
and the other lower with the 338 Lapua bolt-action upper (fun as well, but expensive to shoot)
So, as you can see, there is quite a variety of things and formats you can set up in the AR platform.