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[Darklyte27]

Chrome is put on the barrel to make it last longer. If you want accuracy Stainless steel is what you want.
From aimsurplus,

These barrels are made to the Mil-Spec for the M249 SAW. They are the correct Certified CMV material and they are also Hard Chrome lined to the M249 SAW Mil-Spec, which is almost 2X as thick as the Hard Chrome on a Mil-Spec M4.

Overview

Cold Hammer Forging of barrels has been known for decades to produce the most accurate, longest lasting rifle barrels obtainable. The Cold Hammer Forging of barrels is accomplished through intense hydraulic pressure applied at opposing angles by carbide steel hammers. During the hammering process, a mandrel is inserted into the bore while the carbide steel hammers shape the barrel around the mandrel creating the chamber, the lands, and the grooves. In addition to the aforementioned benefits, the Cold Hammer Forging process creates a defect free bore and the most consistent chamber possible.

http://www.aimsurplus.com/product.aspx?item=XAIMDD16BAR12&name=AIM+16%22+CHF+.223%2f5.56+BAR-12+Upper+Receiver&groupid=586

I got one of these uppers, http://www.aimsurplus.com/product.as...er&groupid=586

[artoaster]

I would go with hammer forged, chrome lined, chrome moly vanadium (CMV), magnetic particle inspected (MP) and high pressure tested (HP).

These barrels are best for durability and reliability. Palmetto State Armory and others have them and they're what you want on basic carbine or rifle.

If you go custom you can get into specifics and maybe increase accuracy potential in sub-MOA. Otherwise 1-2 MOA in mil-spec type barrel is fine.

Another read:

http://www.lasc.us/RangingShotBarrelMakingFeature.htm

[ClarenceBoddicker]

Hammer forged barrels are way stronger than all others, due to the metal grain structure that follows & reinforces the rifling pattern. A chrome lined barrel can be just as accurate is a non chrome lined one. A chrome finish inside a junk barrel does not cause it to be inaccurate, the low quality barrel itself does. A chrome lined barrel will reduce wear caused by gas erosion & from high heat. A chrome lined barrel is much easier to clean. All semi-auto survival/combat weapons should have a chrome lined barrel. Many barrels that the not made to military specifications can wear out in a few hundred rounds, if shot a lot when the barrel gets hot. A target rifle does not need a chrome lined bore.