Looking for a 20", crome lined, 5.56 chamber. Thanks.

Accurate, chrome lined barrel.  Kind of like asking Cheech and Chong for their best clean joke.  I'm sure that they exist, just haven't encountered many of them.  A chrome lined barrel is created by oversizing the bore, shooting hard chrome down the bore, then recutting the bore.  If all the planets are aligned and two chickens are sacrificed in the pale moon light then a nice uniform coat of chrome will exist in the barrel.  When this happens you have a nice accurate durable barrel.  However most of the time you get a variable coating of chrome, which is nice and durable but as accurate as filling your NCAA bracket out in November.  

That's why if you are looking for accuracy going with a SS or chrome moly barrel is the path most traveled.  Just some food for thought.

Jesse    

Jesse is correct. Thus, I also will not state one manufacturer is better than another.

We are considering an ar. It will probably be relatively accurate, period. The design, however, has the potential for truly, exceptional accuracy.

A bigger factor than chrome lining is the chamber and the ammo.

The differences in dimensions are minute but significant. A chamber cut to 5.56 NATO has a great tolerance than one cut to .223 Remington.
Thus the .223 Remington rifle will probably be more accurate.

If one consumes various surplus ammo in one session the potential accuracy of the rifle can not be realize either.

Chromed and accurate is not an impossible compromise. But, it is a compromise.

My experience is limited but it suggest that you get what you pay for. My ar is very accurate. My friend's is better. But, he paid five times as much.

Dan

Accurate chrome lined barrels do exist - a case in point is the FN SPR rifle chambered in .308 and 300 WSM.

http://www.fnhusa.com/contents/r_spr_a1.htm

While chrome lining barrels are indeed not an easy task, recent developments in manufacturing have been made to ensure the even coating of the chrome in the barrel internals.

With that said, I have an ongoing project building an M16 based 5.56 SPR and am also insterested in finding out the most accurate chromelined 5.56mm barrel.

COLT!

Ditto!

No one!

Why would anyone want a chrome bore for a rifle used as "regular" shooter.  We aren't in Vietnam here you know.  Clean your gun once in a while and chrome bores / chambers are unnecessary.

It's a proven fact that high-carbon (without chrome) or stainless barrels are the most accurate.

Bushmaster
I have several and they shoot as well as my stainless national match.  

I've read that chrome lined barrels aren't supposed to shoot well.  Apparently nobody has told Bushmaster!

My main rifle has a Bushmaster 20" National Match chrome lined barrel, 1 in 9 twist, NATO spec 5.56 chamber.

With my good handloads,  I routinely get five shot groups in the half inch class, and have shot groups as tight as 3/8ths of an inch with precisely matched ammo components and loadings.
(Weighing every component, matching and uniformly trimming brass, inspecting bullet bases, etc.)

It's possible that this setup can shoot even better, but I have a slight problem in that the groups I shoot end up being invisible in the 'scope as the crosshair COMPLETELY obscures the groups unless I shift the point of aim slightly to take a look!   I need a 'scope with a finer crosshair before I can get better!

In theory, I will be able to improve (!!) my load's performance by switching from Hodgdon H322 powder to Vihta Vuori N133, which has superior temperature stability.

Tight enough for ya?  [;D]

Anyone who would opt for a non-chromed bore on an AR when one was available is making a bad decision as chroming makes cleaning MUCH easier, more than doubles barrel life, and (obviously) doesn't hurt accuracy to any noticeable degree if it's a quality job.  

If I were shooting the nationals, I'd go directly from a chromed bore to a top flight stainless barrel, and I wouldn't select a non-chromed, non-stainless barrel for any reason.
There IS no advantage to doing so.

Among chromed barrels, I would only buy Bushmasters or Colts.  Both make top notch barrels.

I might be tempted to add FN barrels to the list, but I haven't had a chance to try one out under conditions that allow me to determine their real accuracy potential yet.

CJ

If you would be so kind as to share where you get your statistics on chrome "more than doubles barrel life."

As far as the high end national match guys, they use SS and stay away from chromed barrels because they are not as accurate.

Many of us cannot outshoot a chromed barrel, so we are happy to not need the high end SS barrels.

I was under the impression that all of BM's barrels were chrome-lined [b]except[/b] the DCM(NM) & Varminter.

NM is not DCM but you probably can't out shoot bm's chrome lined.