I have an older postban Bushmaster XM-15-E2S with a 20" Heavy Barrel, and less then 400 rounds through the barrel. The upper dose not have an elevation adjustment. And it is about 95%.
Question #1. What makes the AR a A1, and #2. What is its value?
Thanks, Kirk

It's "A-nothing."  

The upper is more accurately a C7 upper, there was no US military upper with a brass deflector and non-adjustable for elevation sights.

This is a nice upper as the elevation is rarely adjusted once the rifle is zeroed, so keep it simple.

Value?  A 20" HBAR barrel has little demand and is about $185 new.  The receiver is more in the $125 range new.  

You thinking of rebarrelling?  Have the barrel turned down to M16A2 profile and this makes a very nice weight rifle.  Probably under $100 to have this done.

-- Chuck

Turning the barrel down to A2 profile (with reparkerizing) is a $50 job at Kurt's Kustom, add $12 for shipping and Handling.

Kurt does a great job and turned my HBAR into a great shooting much lighter A2 profile.

Thanks, I think that im going to keep the upper but i want to find a 16" barrel, How are the RRA Barrels?
Thanks for the info, Kirk