How can I tell if my barrel is Chrome-Lined?

[ZombiesAhead]

I have an AK-style rifle that I can shine a light into from the receiver end and it looks pretty darn shiny. I'm pretty sure it's chrome lined.

However, I recently bought a Bushmaster AR-15 and while I should have done more research, I needed it NOW!

The salesman informed me it had a semi-heavy barrel (and indeed the barrel seems heavier than that of a friends' RRA AR-15). It is a 16" and he claimed it was chrome lined. It's hard to look inside because of the small caliber to check for chrome.

How can I tell for certain it is chrome? If it is shiny at all, does that mean it is chrome-lined?

 

[rcmodel]

You can't tell chrome from a good shiny steel bore by looking at it.

Colt AR chrome bores are kind of a duller mat look then a highly polished steel bore would have.

You should be able to see where the chrome stops on the muzzle and on the chamber end of the barrel.
Look for a change in color from white to the blue, black, parked, whatever, finish.

rcmodel

 

[Drail]

Like the last poster said it will have a duller sheen than polished steel. The easiest way to tell is that almost nothing will stick to it. You can almost wipe fouling off with a dry rag.

 

[Clemson]

A drop of cold blue will stain the bore if the barrel is not chrome-lined. It won't touch the color of a chrome-lined bore. After you shoot it, the color is gone, so this test won't hurt either barrel.

Clemson

 

[Onmilo]

Look on the barrel towards the muzzle at top or bottom.

There will be a stamp.
If it is a Bushmaster barrel the stamp will read something like; B MP 5.56 NATO 1/9
The B indicated a Bushmaster manufacture barrel, the MP indicates magnaflux particle inspection of the barrel and a chrome lined chamber and bore.
The other numbers indicate the type of chamber dimensions and the twist rate of the rifling.

Almost every mil-spec type barrel manufacturer will use similar stamping on their barrels
Colt will use C MP 5.56 NATO 1/7 for chrome lined chamber and bore and 1 in 7 twist
You mat also see one stamped C CB 5.56 1/12 or CC 5.56 1/12