I am wanting a 5.45 upper for my SAW/Olympic conversion and am wondering if these are any good? Since the barrels aren't chrome lined I was wondering about the life expectancy on these as well. I did see a S&W upper on another board for sale. I did notice that it has a chrome lined barrel. Here is the link to the site. All constructive comments welcomed. Any links to other discussions welcomed as well. Thanks, delta-10

http://www.huldraarms.com/uppers/product_76b374d367d8/

I have probably 9-10 tins of 5.45 through my Adam's Arms upper(same system you are looking at).
Chopped it to 11.5, opened up the gas port, installed a Carlson Nitro flash enhancer, Wolff extra power spring and it just runs and runs...and breaths fire.
I have broken (2) C-clips that hold the plunger in on the gas adjuster ($.10 part) and (1) firing pin on the last tin of ammo.
No clue on true accuracy, it only sees mag dumps, but it is still minute of burning car at 100yd.