A number of persons on this forum have indicated that the Rock River AR15 chrome moly barrel has an edge on the Bushy for accuracy. Basically that chrome moly or SS is more accurate than chrome lined.

Since my intention for this rifle is primarily target shooting, is the accuracy factor enough of an issue to chose the RRA over the Bushy?   Groups of no more than 1.5" at 100yds would be acceptable.  I like the looks of the 16" carbine but am making the assumption that the 20" barrel is more accurate for longer yardages like 100-200yds.

When target shooting the standard AR15 rifle are most shooters going for targets at 25 to 50 yards or is 100 to 200 yards typical?

Target shooting at pistol ranges need not have a CMP heavy barrel on an AR15.  

There is no difference in accuracy between high quality chrome lined bores (Bushmaster and Colt's) and ordinary non-chrome lined barrels such as sold by RRA and Model1 Sales, etc.

Folks who sell non-lined barrels would like us to believe differently, of course, just like folks who only sell HBAR barrels would like us to somehow believe they're more accurate.

True match barrels are, of course, unlined and heavy.  But that confers no special accuracy to all unlined barrels or all heavy barrels.  V8s ain't always faster than 4 cylinders, I know of 4 cylinder street machines with 0-60 times in the 4s.  Not even a good V8 (or V10) will beat a good 4 every day.  Seems as if some folks are buying the "unlined heavy is more accurate" nonsense; there's more to it than that.

Even a M4 length barrel will shoot 1.5" groups off the bench with macth ammo if you do your part.

All barrels are chrome-moly steel, nothing special about that.

Ammo and your shooting will be the major determinate of accuracy at pistol ranges like these.  Unless you're using a sling or a bench rest you're not going to get 1.5" groups at 100 yards with any rifle unless you routinely place in the President's Hundred at Camp Perry.  

-- Chuck

As the owner of a RRA LEGP M4 and a Bushmaster M4, I can verify what Chuck is saying.

Either rifle will easily meet your needs.

for what it's worth on chrome lining: i was casting bullets for my Bushmaster and had to "slug" the bore. to slug a bore, one takes a pure lead bullet and taps it down the bore to get the exact diameter from grove to grove. when i slugged my BM, it was tight initially (as expected) for the first 3-4". then, the slug met very little resistance for 8". finally, resistance was met again for the last 4". this implies the chrome lining is not consistent. i call BM and they said to return the upper and they replaced it promptly. i slugged the replacement and it slugged as expected, same resistance throughout the bore.