AR Sponsor
Posted: 6/3/2016 10:57:19 AM EDT
|
- Wrench flats machined on all 4 sides? - The different location of the cutting line behind the shoulder, suggesting a different machine or setup. This line appears to be on the majority of early tubes and current ones for that matter. I do have one early full round pictured with no cut line, oddly it is nearly the same color these have peeking through. Its a full round 601. -a slight rounding on the rear edge of the shoulder Other notable differences: These appear to have the gold/green anodizing underneath like some of the early 603 uppers had. Where have you guys seen these attached to guns? 603? GM? HR? mixed in sub contract? Next to some early ones for comparison of tooling cut and color. The square ends are the two on the right. |
| I've also noticed some 604/M16A2 rebuilds also had wrench flats machined or filed into the receiver extension as well. My guess was it was a CATM practice to do this to facilitate ease of removal of the receiver extension. Too bad too, seen a lot of early receiver extensions that have had this modification. |
Boywonder777 sold me some crushed chunks of GM lowers, one had a stub of bright gold tube still stuck in it. I also see similar bright gold rings showing in pictures of real GM rifles. Below are some of the original chunks:
I'm not sure if all parts were 6061 and were then changed to 7075, but the different alloy might have something to do with the different colors. I have an early buffer tube with the hole drilled in it and wrench flats cut in after the fact, it has a slight brown tint to it. It looks like someone rubbed the whole thing with steel wool so the edges of the exposed ring are worn through to bare aluminum so I put it in this beater as if it were partially rebuilt at some point in its life: 
I like your brown tint early buffer tube, it is nice to see a mix of colors instead of everything looking plain gray. |
| My Buddy Nicky is the "manual guru", we recently had reason to look up the question of the extra added 2 wrench flats totaling 4. It is well described in manuals. Off hand it may be one of the 1968 dated ones, but just off the fone with him he says most likely the 1971 TM, not FM, TM manual. He's gonna check when he gets home from work. I'll update when he confirms. |
|
Thank you for the replies! I have been collecting those different colored early ones for awhile, I think we share a desire for the odd and early anodizing colors somebob  I would like to hear the reference when you find it M1sniper! I am curious though what led you to looking on the topic? Thinking out loud, maybe I should compare it to my m16 barrel wrench? I bet the larger side of the rectangle is the same as the compensator... I got these with the intention to cut them down for 607 buffer tubes, but I think Ill save the ones with 4 flats for awhile longer. |
AR Sponsor