I am looking to get another A3 16" upper.
I understand that the M4's have feed ramps cut in them and some are available chrome lined. Could someone please give me the benefits or problems with having the chome lined barrels or feed ramps?
Also if I get a 5.56 chamber are there problems with firing commercial .223?

Thanks
Bill

There are no problems with a chrome lined barrel, if anything, it aids in reliablity with feed and extraction.  The chrome lined barrel will last longer, even though most shooters won't shoot enough to see the difference.  I see a massive difference in cleaning, with the chrome barrel coming much cleaner much quicker.

The 5.56 chamber will fire the .223 and 5.56 (military surplus) ammo without a hitch.  The .223 chamber is a bit tighter, and will not work as well with 5.56. It should work most of the time, but most of the time isn't good enough for me.

No doubt you will hear some people comment that a chrome lined barrel isn't as accurate as a stainless steel or unlined barrel.  True, but unless you are good enough to notice an 1/8th inch difference at 100 yards, you will never notice.  Regardless of how good many people claim to shoot with open sights at long distance on this board, most are telling fishing stories.

I completely agree![:D]

I second the motion.

Yep, what Stick said.