Problem is there are no marking of any kind on it. It's a A2 style upper, with an H-Bar type barrel (at least I think so… haven't had the guards off since I bought it) The only thing I know for sure is it has a Bushmaster bolt/carrier because I bought it new some years back.

No marking on the barrel or upper, though both are nicely machined and finished. The front sight tower is by far the nicest I've ever seen machining wise. lol

http://photos.imageevent.com/cas6969/web/coltup.JPG

http://photos.imageevent.com/cas6969/web/coltuppe.JPG

I think the only noteworthy marks on it are wrench marks on the flash hider. (and a little flaw in the seam of one of the guards.
Has a sling stud added (bi-bod?) and marks like it wore a handle scope mount.

http://photos.imageevent.com/cas6969/web/flash.JPG

Since it's not marked I don't know what the twist rate is, so I shot some 75gr Prvi ammo through it and it did pretty well, so it's probably 1-7 or 1-8. This was shot at 100 yards, with the large aperture in the pouring rain. The target is a mess from 2 other rifles but I didn't feel like getting soaked to change it. It's not sighted in as I was shooting at the brown circle, but in the rain I couldn't tell where they were going… nor could I see through the smaller peep.

$350 shipped.