I've had this barrel for 12-13  years and think it might be an original 605 carbine barrel.  It came from the estate of a friend who collected U.S. Military guns but stopped in the 1980s to focus on U.S. knives, medals, and unit histories. So it definitely isn't something modified in the last couple years. Unfortunately, it was acquired without a front sight base, which I think would have been a cast type, and a real SOB to replace properly.  It's photographed next to a Model 02/early XM16E1 barrel, the closest thing I have to a match.

The only markings are the VP proof between the FSB rings and the C on the collar.  The length is 15 3/8" measured with a rod to the bolt face.  To my eyes, the finish on the threads and muzzle face look original and the threads certainly look good enough to be factory made.  Sorry I didn't snap a photo of the middle but they all kind of look the same there.  Opinions are welcomed.  Thanks.

Rick

Have you checked the twist?

That's a good question....no, I haven't but will when I get home later.

I don't recall seeing an original 605, but would guess that one would have a "step up" before the threaded section like other Colt barrel lengths.  My guess, then, is that this one is cut down from a longer barrel.
But that's a guess.  

IIRC there were only about 50 model 605's produced, I think the chances would be slim, but you never know.

Very nice barrel.  Thanks for sharing the pics.

Looks like a great start to a 605 build.

What are your plans for this barrel?  How does the bore look?  

Contact me if you're thinking of selling.


Quick picture of my dedicated 22LR 605 style barrel assembly.

Looking at tgus' 605, there isn't enough barrel to have a step. It looks very similar to the one posted here. It could very well be an original.

I checked the old pics and I think you're right.  I also noted Todd's is M-VP marked.  
I'll be interested to hear if this one is 1-12 or 1-14.

Another thing that struck me was that the finish looks original, including the threads. Cut-down barrels typically don't have parked threads. A little thing, but the barrel looks really good. I too am interested in the twist.

Good comments so far.  The twist is 1-12 so it definitely isn't really early.  If I'm reading things correctly, that VP proof without the magnetic particle M stamp should date it in the 1963-early 1964 period, yes?  Do we know if all the known 605 rifles are grouped in a narrow serial range or if Colt assembled them over a longer period of time?

My suspicions regarding originality of this thing follow the thoughts of others here.......period markings, factory looking threading, and uniform finish.  Added to that is knowing where it has been for 12+ years and probably well before that.  My friend collected aggressively from the late 1950s through the early 1980s and had some killer U.S. Military guns, including a complete Pedersen Device setup, ramrod bayonet M1903, and others.  My 601, M14, M2 carbine, and gas trap M1 rifle all came from him. But when he moved on to other militaria, he really turned off the switch on guns.  Not saying it's impossible that he picked it up at a gun show after 1981 or 2,  just pretty unlikely.

And back in those days there wasn't much appreciation of the oddball AR variants, and nobody was building SBRs for fun like we do now.  Nothing conclusive, of course, but good circumstantial evidence from my perspective.  Thanks again for all the input.

Rick

Having never seen a stripped one, I'm not sure how we could verify it, but since it's a 1-12, I have to admit I see nothing to indicate it's not a 605 barrel.
It's a very cool artifact!

Things that come to mind, it looks like original finish and the extension / feed ramps / lugs face where a bolt carrier leaves a footprint look very unused.  Does it look like it had ever been used?  I see lube / grease by the dowel pin so it looks like it was in a receiver at one point in time.  Since the FSB is off, what size is the gas port?  Is the gas port parkerized or bare? Any carbon in the gas port?

Now that you mention it, I hadn't noticed how nice the barrel collar is.  It really does look unused with just minimal markings.  It has definitely been on a receiver as the area forward of the chamber has the telltale smudges from being held in GI type aluminum barrel blocks.  The bore is really nice but I don't have a 5.56mm erosion gage handy to verify anything beyond that.

The gas port measures .092".   I really can't tell about the finish in the port other than it's "dark", maybe from Parkerizing or 50 years of aging.  Even with a look through the inspection microscope at work tonight it looked inconclusive.