I built this one myself and it functions flawlessly. Has just under 800 rounds through the barrel.
This upper wil eat anything anytime. It has never malfunctione, even with Wolf.
Has some scratches on lower/front barrel from field/range work. A scratch or two on the upper receiver.
It is a hybrid of the following:
1) Custom 16" Heavy Barrel (chrome moly steel) w/milspec 7.62x39 chamber, recessed crown, shaved sight tower with A2 sight post.
2) New Colt? (can't remember...might be BM) hand guards with heat shields AND proper mount for Harris Bipod.
3) Colt A1 slab-side large hole upper W/Offset Bushing Installed. I pickd this up from a guy who tried to custom mount an A2 sight on it (note cut-away at sights). When it didn't work, I bought it from him and put the A1's back on. Works perfectly.
4) Colt carrier
5) Charging handle I believe is Colt. Looks like Colt, feels like Colt.
AND...a used 30 round USA Frankenmag.
$400 + shpg. FIRM