OK, so maybe not super unusual, but definitely not run of the mill:

I have an upper receiver I bought from another guy that is black with engraved and painted T-markings.  The barrel on it is a 16" dark gray parked M4 profile with chrome lining.  The only markings on the barrel are the stamp "MP" on the top near the muzzle, which I take to mean "mag particle tsted" per standard barrel markings.  The twist is not marked, but appears to be 1 in 9.  the front sight base is forged with a bayonet lug, and has the raised forge markings "F01[symbols in a circle, maybe R1 or M]2" on the right side.

Any guessed who made it?  The barrel nut doesn't have any signs of having been removed/reset or buggered, so I would hazard a guess it could be the original barrel on the upper receiver.

Oh, and it shoots great!  Just want to know who made it!

Dawg

Ok, let's try this with a simpler question:

has anyone ever seen a barrel marked solely with "MP" on the top near the muzzle?

Got me by the balls.

But FYI,

M = Magna particle tested
P = Proof Load

Let me give you two possibilities;  both off the top of my head.

1)  A lot of Colt stuff has been coming out recently, with fewer markings than they used to put on.

2) Continental has been putting out bolts simply marked MP, and I'm wondering if they're not doing the equivalent w/their barrel markings.

My own hunch is on number 2, but since I've not seen any recent Conti barrels, I have to label it a guess.

Well, the barrel is at a minimum two years old, as that is when I got it from somone else, and I honestly don't know how long he had it for.

I guess the other question is what companies are MP testing their barrels?  I know Colt does, but how many others do?  Not many I would imagine...

Hmm, well at least those are soem leads....if anyone else has thoughts, please speak up!

Have I offically stumped the Hive Mind???