..So my long wait is over- I finally received my Gov't A4 midlength upper from RRA with the optional Surefire handguards on time as promised- since this is my first experience with RRA, could some experts shed some light regarding some questions I have:
1-the upper came with a triangular handguard cap with M85 Surefires (I thought the triangle type are fr VN era?), dont all modern AR's come with round ones?  Are there any pro's and con's to having round vs triangle caps?
2-How can I tell if the barrel is chrome lined, there are no markings on the barrel.
3-From what I have seen online at RRA all their uppers have a side sling adapter, my new upper with the factory installed Surefires have a standard sling adapter (below the front sight)

Overall are all these characteristics normal of a RRA upper with Surefire from the factory or did they make a boo-boo???

Thanks all for your patience and insights!

If you check out RRA's Website under Surefire they list the mid-length as follows:

AR3010 . . . . . . . . SureFire M85 Tactical Rail Handguard, Mid-Length
. . . . . . . . . . . . . . For triangular handguard cap.

For assurance that you got a chrome-lined barrel, check out the 'Industry' Form, then 'Rock River Arms', then look at the second sticky.  

They don't show a side sling mount in the picture of the Mid-length Upper (AR0375X  Mid-Length A4 Upper Half), nor do they list one as an option.  However, they do show one with the Elite CAR A4 Upper (you get both the std and side mount).

I got a new Elite CAR A4 rifle a couple of weeks ago and mine came with triangular handguard caps and a side sling mount. FWIW, my new RRA Mid-length, chrome lined barrel is marked '212' under the gas tube just in front of the delta ring just like Steve's list said it should.

I'm sure that if you call them, they will sell you a side sling mount for a nominal amount.

they probably expect you to find a way to mount your sling to your railed foreend now...

Most (but not all) mid-length barrels use triangular handguard caps.

Are there benefits to having triangle vs round caps or is this just in cosmetics?  Thanks gents.