My new Panther Classic sounds exactly like what you've described. It is stamped A-15 and has the A2 upper. It also has a very heavy barrel with 1-in-9" twist. The barrel is .980" under the handguards. I ordered this configuration because it was the exact exterior dimesions of my issued M16A2's in the Cavalry.
I have had a few sub 1/2"@100yds with the factory A2 sights. See my range report on this page. I know it will shoot 1/4" with a scope. I nearly held one group at .251", but got excited. The 5th shot went wide and brought the group to .476".
My younger brother was down this weekend to try it out . We put 90 more rounds through it. It has now went 480 rnd without a malfunction/jam.
My next upper will be the 7.62X39 for a short range deer combo. Havn't decided on upper reciever design yet. I think it'll be a flat-top and a good low power, light gathering scope. I'd like to find a 4X with at least a 40mm objective.