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Posted: 11/19/2010 9:28:11 PM EDT
Do you guys think it's a bad sign that I've been noticing more and more when the clock says 6:33?

nevermind, I'm sure it's normal.

Anyway, I was just perusing through my folder of DOE pics (shut up), and happened across this one:



I have 2 copies of it, so I must have thought it was cool enough to save, more than once.  But I have no idea where I got it.

Anyone know where I found this?
I know they made a fixed front sight version, but does anyone know anything about the crazy handguards?  Plastic? Metal?
Other odities include the ambi-selector, dimpled takedown pin?, and the double mag release (or something?)

I kind of dig the look, but know nothing about it, or whether it was an actual Colt model, or some civie knock off?

Off to my Black Rifle I & II for research!
Link Posted: 11/19/2010 9:48:50 PM EDT
[#1]
It's an actual Colt model made for the DOE.

You see the uppers for sale every now and again; I just ran across one for sale which had a fairly lengthy description of features; am looking for it.

0633 variant I think it was but I'll have to check.
Link Posted: 11/19/2010 10:17:12 PM EDT
[#2]
Found it in the Black Rifle II, bottom of page 126.

Has the above photo, and the following caption:

167. Right side view of an experimental version of the Model R0663.  Note the one-piece aluminum handguard, andthe ambidextrous selector and bolt catch.

So handguards are aluminum.  Never seen them for sale but would love to get my hands on one. . .
Link Posted: 11/19/2010 11:03:21 PM EDT
[#3]
I'm sure one of the guys here could make them, we have some amazing folks building retros.
Almost looks like the HG also acts as the barrel nut, similar to a freefloat tubular HG. I wonder if the front has any holes for a barrel wrench.
Oh, what toys one could build with a CNC lathe......
Link Posted: 11/19/2010 11:10:00 PM EDT
[#4]
Ya, I was figuring it was the barrel nut too. There are 4 slots on the front that I was wondering about. At first I was thinking they were for a sling, but maybe they're (also) for tightening the handguards?  Though they don't look like they'd line up withe the three pronged wrench very well.
Link Posted: 11/21/2010 5:21:44 AM EDT
[#5]
Quoted:
There are 4 slots on the front that I was wondering about. At first I was thinking they were for a sling...


I would think almost certainly for a sling...Especially if it has an integral barrel nut/thread...(no way to tell where the sling slot will end up when it is tightened...hence the 4 slots)...  

Quoted:
I'm sure one of the guys here could make them...


Pretty much anyone here could turn one on their lathe, threaded to act as a barrel nut, and then taper the body, mill the flutes and the slots...but a lot of time involved; a lot of material removed...have to start with a really thick tube or a solid rod...The front flange looks to be about 3" OD...  

Almost looks like the HG also acts as the barrel nut...


And would probably be hand tightened...You can get a lot of torque with your hand...(or a strap wrench)...  



Link Posted: 11/21/2010 9:26:57 AM EDT
[#6]
Quoted:
Quoted:
There are 4 slots on the front that I was wondering about. At first I was thinking they were for a sling...


I would think almost certainly for a sling...Especially if it has an integral barrel nut/thread...(no way to tell where the sling slot will end up when it is tightened...hence the 4 slots)...  

Quoted:
I'm sure one of the guys here could make them...


Pretty much anyone here could turn one on their lathe, threaded to act as a barrel nut, and then taper the body, mill the flutes and the slots...but a lot of time involved; a lot of material removed...have to start with a really thick tube or a solid rod...The front flange looks to be about 3" OD...  

Almost looks like the HG also acts as the barrel nut...


And would probably be hand tightened...You can get a lot of torque with your hand...(or a strap wrench)...  


Being 9mm, there's no gas tube so I imagine you could get a barrel wrench to those holes in the back of the handguard.

My understanding of the reason for the flair on the front of the handguard was to keep your forward hand from getting in front of the muzzle during recoil.
Link Posted: 11/21/2010 10:03:23 AM EDT
[#7]
Scanned in from Black Rifle II for comparison:



Note that the sling on the later 633 is attached to similar 45 degree slits on the sheet metal handguard.
Also interesting that the prototype was on an A2 lower

Here's some rough measurements:



If any of you amazing machinists out there are interested in this as a commission project or something, send me a note with an estimate.
Link Posted: 11/21/2010 10:14:47 AM EDT
[#8]
Maybe I'll look around for a 6" length of 3" dia. aluminum the next time I'm at the salvage yard. I can write a program to shape the OD, bore and thread the receiver end, and then part off easy enough. The flutes, sling slots, and holes at the back can all be done with an indexer or rotary table. I'd probably have to turn it around, chuck up on the receiver end, and bore from the flange end to lighten it up some, but I can do that manually also.

Edit: Anybody got an extra barrel nut I could use to take measurements from?

After looking at the photo for a while it looks like there is a pin securing the front of the HG. Makes me think there is a custom barrel nut(the holes at the rear for a barrel wrench) and the HG slides over/up against it and is then secured to the equally custom FSB with a dowel or roll pin. Either way is doable.
Link Posted: 11/21/2010 10:49:20 AM EDT
[#9]
I can send you a barrel nut Pan. Send me your info.

I saw those marks too, but honestly they just look like scratches to me (looking at the book now).
As an additional arguement for a one piece design, the side flute is not at 90 degrees from the top. The photo is angled slightly up (you can see into the mag well slightly), but the whole handguard appears to be biased toward the bottom.
Link Posted: 11/21/2010 11:46:42 AM EDT
[#10]
Edit: Anybody got an extra barrel nut I could use to take measurements from?


I have one i can run down to you tomarrow aftermoon.

Whoopie
Link Posted: 11/21/2010 11:48:23 AM EDT
[#11]
I would be concerned about the HG barrel nut thread...If you thread the aluminum, even 7075-T6, you run the risk of stripping it (either the male or female)...or even galling...

I would use an OEM steel AR15 barrel nut, and relieve the end of the HG...Tighten the nut, and then slip the HG over it...before the FSB is installed...  
Link Posted: 11/21/2010 12:11:08 PM EDT
[#12]
Quoted:
I would be concerned about the HG barrel nut thread...If you thread the aluminum, even 7075-T6, you run the risk of stripping it (either the male or female)...or even galling...

I would use an OEM steel AR15 barrel nut, and relieve the end of the HG...Tighten the nut, and then slip the HG over it...before the FSB is installed...  


I think the threads will be fine as long as the barrel nut/HG and receiver are both hard coat anodized. Anodized aluminum AN fittings seem to work fine.

Edit: I used to be concerned about the barrel nut being made from the proper steel etc. until it was pointed out to me that the barrel extension/bolt lugs are what lock up and take the recoil. I understand there are aftermarket rail systems that use anodized aluminum barrel nuts also, but I haven't looked for myself to confirm this.
Link Posted: 11/21/2010 5:46:47 PM EDT
[#13]
I have a shorty FreeFloat HG from an AR pistol upper and the barrel nut part is hard anodized aluminum, as are most FF HGs I have seen.
Link Posted: 11/21/2010 6:00:31 PM EDT
[#14]
Quoted:
I have a shorty FreeFloat HG from an AR pistol upper and the barrel nut part is hard anodized aluminum, as are most FF HGs I have seen.


It sure would make it easier to go the one piece route on the HG. If it's a free float the FSB will be easier to replicate also. Maybe I was over analyzing the photo.
Link Posted: 11/28/2010 6:34:59 AM EDT
[#15]
I wrote a program this morning for the OD contour and barrel nut threads. Time to look for some 3" aluminum barstock.

Also, this site was passed on to me that has the barrel nut drawing along with just about everything else.
Blueprints
Link Posted: 11/28/2010 6:55:33 AM EDT
[#16]
Sweet!
Link Posted: 11/28/2010 7:34:55 AM EDT
[#17]
Quoted:
I wrote a program this morning for the OD contour and barrel nut threads. Time to look for some 3" aluminum barstock.

Also, this site was passed on to me that has the barrel nut drawing along with just about everything else.
Blueprints


That is one slick site...
Link Posted: 11/29/2010 1:24:42 PM EDT
[#18]
I did the turning for the HG today, just need to cut the flutes and the sling slots. Here it is screwed onto the de-milled upper from the 656 project, it's the only bare upper I have here ATM. Tumerboy do you want me to lighten this up as much as possible? It will leave the front opening at around 1-5/8" if I bore it out as much as I dare though.





With the collet and center spud I'll use to do the flutes and slots.
Link Posted: 11/29/2010 2:42:14 PM EDT
[#19]
Holy crap my65pan - you ARE the man! You never cease to amaze me. Tumerboy - have you noticed the weird mag catch? Extended? Ambi? I see it has an ambi selector - I wonder if it's set up to work in conjunction with the bolt catch somehow, so when you put a mag in and it catches, the bolt releases. It looks like a full-fence lower that was machined to allow the modification, simply making the mag release larger doesn't make sense - it's extended up. I really need to buy a copy of TBR.
Link Posted: 11/29/2010 2:43:15 PM EDT
[#20]
I know I shouldn't, but I'm constantly re-amazed with the talents here!
Link Posted: 11/29/2010 3:19:07 PM EDT
[#21]
Quoted:
Holy crap my65pan - you ARE the man! You never cease to amaze me. Tumerboy - have you noticed the weird mag catch? Extended? Ambi? I see it has an ambi selector - I wonder if it's set up to work in conjunction with the bolt catch somehow, so when you put a mag in and it catches, the bolt releases. It looks like a full-fence lower that was machined to allow the modification, simply making the mag release larger doesn't make sense - it's extended up. I really need to buy a copy of TBR.


Thanks Morg, I was looking at the mag catch and it looks to me like the bottom half is a modified mag catch and the upper portion is a separate ambi bolt release. Not sure how that works, but it sure gives a guy something to think about.

Link Posted: 11/29/2010 4:56:44 PM EDT
[#22]
Amazing work!  That thing is beautiful.  

Most all inexpensive free float tubes and rails are aluminum nuts.  Some of Yankee Hill's tubes require a strap wrench to install.

Link Posted: 11/29/2010 5:20:51 PM EDT
[#23]
Holy Fuck Mark!   That's amazing!

Ya, I'd say open it up (maybe not quite as much as you dare?  Dunno.  Seems like it would have been open enough inside to connect to the holes drilled around the back end?  Though it doesn't look like there would be enough room.  Not sure where it puts that though, nor what those holes are for since there'd be no gas tube.

LOL this is moving faster than I ever expected.  I've got my DOE barrel off at Garrison getting a flip down front sight at the moment.  I've only got one Colt 9mm Upper, I guess I may have to reconsider what I'm building. . . This really was a pondering thread more than anything.  But I'm not opposed to people doing amazing work on my behalf. :P

Morg, ya I certainly took note of that as well.  BRII said it was an ambi Bolt Release:



Presumably the mag catch is modified so that the right side bolt release can move downward a bit.  Sadly, being in CA, this will have to be a stockless pistol, with a Bullet Button. . . no crazy mag catch/bolt release for Tumer.

As I noted in an earlier post, it also seems to have a dimpled take down pin, and is on an A2 lower. . .  I think the barrel is longer than the standard DOE barrel, so I'll have to get something trimmed down to fit.  As well as getting the whole front sight base figured out.  


New question.  What would this thing be called?  Above, the BRII says it's RO663.  But it also calls the DOE 633 below it RO663.  Was the 633 NOT RO633?  Was it RO663, in which case, where's the 633 come from?  Or is that all a mistake in the BRII, and all of it should be listed as RO633?  I guess I've never understood the correlation/difference between common model number, and RO number?


Damn I love you guys!

Link Posted: 11/29/2010 5:35:32 PM EDT
[#24]
Quoted:
Holy Fuck Mark!   That's amazing!

Ya, I'd say open it up (maybe not quite as much as you dare?  Dunno.  Seems like it would have been open enough inside to connect to the holes drilled around the back end?  Not sure where it puts that though, nor what those holes are for since there'd be no gas tube.

Morg, ya I certainly took note of that as well.  BRII said it was an ambi Bolt Release:

http://farm5.static.flickr.com/4088/5195897454_eac633865f_o.jpg



OK, I'll open it up as far as I can then. A straight bore will just barely connect to the holes on the back, but I can cut an ID groove to connect them fully to the ID for ventilation. The holes at the back are what made me think the original design had a barrel nut with the HG as a seperate unit. I assumed the holes were for a barrel wrench.

Link Posted: 11/29/2010 5:47:16 PM EDT
[#25]
Quoted:
LOL this is moving faster than I ever expected.  I've got my DOE barrel off at Garrison getting a flip down front sight at the moment.  I've only got one Colt 9mm Upper, I guess I may have to reconsider what I'm building. . . This really was a pondering thread more than anything.  But I'm not opposed to people doing amazing work on my behalf. :P



Tumerboy, please don't feel like you're commited to this HG. I realize you were just pondering, but I sort of took the ball and ran with it. It isn't done yet either, I've been known to snatch defeat right from the jaws of victory before.

Link Posted: 11/29/2010 6:02:42 PM EDT
[#26]
Ha Ha! No worries. If you get it done, I will surely put it to good use!
Link Posted: 11/29/2010 6:04:03 PM EDT
[#27]
My own uneducated two cents on the aluminum/aluminum threads:

Consider perhaps application of a dry film lubricant to the threads, and then greasing them up heavily before the install.  I doubt you'll have any troubles if you do that.
Link Posted: 11/29/2010 6:25:18 PM EDT
[#28]
Quoted:

http://farm5.static.flickr.com/4088/5195897454_eac633865f_o.jpg


New question.  What would this thing be called?  Above, the BRII says it's RO663.  But it also calls the DOE 633 below it RO663.  Was the 633 NOT RO633?  Was it RO663, in which case, where's the 633 come from?  Or is that all a mistake in the BRII, and all of it should be listed as RO633?  I guess I've never understood the correlation/difference between common model number, and RO number?



I would like to add to the new question and  point out an observation of the weapons in the pic. The bottom one, i'm thinking ,is not an RO633 all though it is simular. look at the plate behind the front sight where the sling is and the front sight. it does not fold, it has a fixed sight on it. so it may in fact be an RO663 and the top one a product improved RO663 proto type as it is made with an A2 type rec. Just something else to ponder.

Whoopie
Link Posted: 11/29/2010 8:22:26 PM EDT
[#29]
Quoted:
New question.  What would this thing be called?  Above, the BRII says it's RO663.  But it also calls the DOE 633 below it RO663.  Was the 633 NOT RO633?  Was it RO663, in which case, where's the 633 come from?  Or is that all a mistake in the BRII, and all of it should be listed as RO633?  I guess I've never understood the correlation/difference between common model number, and RO number?

I would vote for typo.  I'm not aware of any Colt numbers in the 660s, and since there is a 634 and 635, both of which are 9mm SMGs, 633 makes more sense.  As for the lettered prefix, from what I can tell these were only introduced sometime in the 1980s to differentiate between select-fire and semi-automatic only weapons.  They are effectively irrelevant for separating the two categories, as the former have only 3-digit model numbers, while the latter have only 4-digit model numbers.  The prefix only seems to have any clear relevance for 4-digit weapons, where there are multiple prefixes.

The prefix R was initially used for semi-auto only weapons, while the RO prefix was used for select-fire weapons.  This led to a number of lettered prefixes.  The Colt Accurized  Rifle used the CR prefix and the Match Target series used the MT prefix.  With the effective end of direct sales by Colt to civilians, the R prefix was replaced by the AR prefix, and they then added the LE prefix.

There is only one instance I know of overlap, and that is with regards to the 639.  The original 639 was an export/commercial version of the 629, while the number was recycled with the RO prefix later for a 9mm SMG, an export/commercial version of the 635.  The 9mm SMGs are the only weapons I know of in the 600 series that used the RO prefix.  Note the RO prefix is also applied to the M203 (RO801).
Link Posted: 11/29/2010 9:37:24 PM EDT
[#30]
Hmm dunno about numbering.  I'm leaning toward calling it a 663 (even if it's a made up number) just because that's what BRII calls it, and since it was never a production gun, it'll be hard to prove one way or another anyway.

new question:  Assuming Mark get's off his lazy ass and finishes this thing . . .
Anodized, black? or grey?  Hard to tell from the image as everything seems to be roughly the same tone (maybe the receiver is black as well?)  I'd lean towards black, to match up with the actual DOE styling, but who knows. . .
The only Colt 9mm upper I own at the moment is black, though I'm not opposed to changing that.  

Link Posted: 11/29/2010 9:58:04 PM EDT
[#31]
Wow those are SKILLS right there. Neat stuff.
Link Posted: 11/30/2010 5:16:03 AM EDT
[#32]
Quoted:
My own uneducated two cents on the aluminum/aluminum threads:

Consider perhaps application of a dry film lubricant to the threads, and then greasing them up heavily before the install.  I doubt you'll have any troubles if you do that.


Whats the issue?  There's nothing special about it.

Aluminum Barrel Nut

Link Posted: 11/30/2010 9:04:56 AM EDT
[#33]
Just to add to this some more I'm thinking a typo also as I have not found any reference to a RO663 but it falls in the model number range of the 9mm SMG's. as I posted above the weapons in the pics do not have folding sights so they could be another sub variant of the 9mm SMG's.
The RO633 is what we all refer to as a DOE, RO633HB is the same with a hydraulic buffer,.
The RO634 and RO636 are integrally suppressed, 634 having an AWC suppressor and 636 having a KAC suppressor. The 636 is referred to as a DEA, as it was used by the DEA for clandestine lab raids.
The RO635 and RO 639 is a standard 10" SMG with the 639 having 3 round burst,(not an export/ commercial version of the 635).

I would like to know for sure as I am in the process of building all the 9mm variants and so far have a 633, 633hb, 635 and 636.
I missed out on a 634 upper not long ago so the search continues.

Whoopie
Link Posted: 11/30/2010 9:34:37 AM EDT
[#34]
Did the 634 and 636 look the same externally?  i.e. how can you tell them apart except knowing which company's suppressor the upper has?

How as the front cap held on the 636?  I've never seen any good photos from the front, just the side shots.
Link Posted: 11/30/2010 10:09:20 AM EDT
[#35]
Quoted:
Did the 634 and 636 look the same externally?  i.e. how can you tell them apart except knowing which company's suppressor the upper has?

How as the front cap held on the 636?  I've never seen any good photos from the front, just the side shots.


636 is the one with the a2 hand guards with the front sight sticking out the top . the 634 is kind of like a can inside a FF tube i have a pic somewhere i'll see if i can find it. The 636 i have is not a true KAC version and just a copy with a different supressor and is just a represenitive of a 636 for my collection. it is ugly as hell but one of the most fun weapons i have and sounds all most like a pellet gun when you shoot it.
Link Posted: 11/30/2010 10:55:06 AM EDT
[#36]
ya, i dunno that I've ever seen a 634 then. . . maybe a photo would jog my memory.
Link Posted: 11/30/2010 11:07:57 AM EDT
[#37]
Quoted:
Just to add to this some more I'm thinking a typo also as I have not found any reference to a RO663 but it falls in the model number range of the 9mm SMG's. as I posted above the weapons in the pics do not have folding sights so they could be another sub variant of the 9mm SMG's.
The RO633 is what we all refer to as a DOE, RO633HB is the same with a hydraulic buffer,.
The RO634 and RO636 are integrally suppressed, 634 having an AWC suppressor and 636 having a KAC suppressor. The 636 is referred to as a DEA, as it was used by the DEA for clandestine lab raids.
The RO635 and RO 639 is a standard 10" SMG with the 639 having 3 round burst,(not an export/ commercial version of the 635).

I would like to know for sure as I am in the process of building all the 9mm variants and so far have a 633, 633hb, 635 and 636.
I missed out on a 634 upper not long ago so the search continues.

Whoopie

That's the first I've heard of a 636.  I've more often seen 635S for the DEA model.  From what I've read, the 634 was identical to the 635, with the exception of possibly being semi-automatic only.  There was a suggestion somewhere that it used the hydraulic buffer too.  Do you have a source for this info?  I'd love to add it to my notes.

I did forget the 639 was S-1-3.
Link Posted: 11/30/2010 12:07:19 PM EDT
[#38]
For clarification.  Here's what's in my head when I say the following numbers:
(Photos all stolen from the kind and benevolent UXB)

633:


634:
???

635 (top), 636 (bottom):
Link Posted: 11/30/2010 12:21:39 PM EDT
[#39]
The 635 and 636 in UXB's pics are my rifles. He took the pic back in june when i went home to see him. My computer crashed last week and i lost a lot of stuff but i think the pic of the 634 is on the computer at work.

Whoopie
Link Posted: 11/30/2010 12:42:26 PM EDT
[#40]
Quoted:
Quoted:
Just to add to this some more I'm thinking a typo also as I have not found any reference to a RO663 but it falls in the model number range of the 9mm SMG's. as I posted above the weapons in the pics do not have folding sights so they could be another sub variant of the 9mm SMG's.
The RO633 is what we all refer to as a DOE, RO633HB is the same with a hydraulic buffer,.
The RO634 and RO636 are integrally suppressed, 634 having an AWC suppressor and 636 having a KAC suppressor. The 636 is referred to as a DEA, as it was used by the DEA for clandestine lab raids.
The RO635 and RO 639 is a standard 10" SMG with the 639 having 3 round burst,(not an export/ commercial version of the 635).

I would like to know for sure as I am in the process of building all the 9mm variants and so far have a 633, 633hb, 635 and 636.
I missed out on a 634 upper not long ago so the search continues.

Whoopie

That's the first I've heard of a 636.  I've more often seen 635S for the DEA model.  From what I've read, the 634 was identical to the 635, with the exception of possibly being semi-automatic only.  There was a suggestion somewhere that it used the hydraulic buffer too.  Do you have a source for this info?  I'd love to add it to my notes.

I did forget the 639 was S-1-3.


I have allways seen the DEA model refered to as a 636 and have seen the 634 listed before as you state and also as the awc suppressed model. So i may be wrong about the 634 so don't take it as gospel. the one that was for sale was listed as a 634 upper and i have seen reference to the 634 as a suppressed model though i cant find it at the moment. So i may be wrong about that designation but would like to find out for sure.

Link Posted: 11/30/2010 1:06:55 PM EDT
[#41]
Quoted:
I have allways seen the DEA model refered to as a 636 and have seen the 634 listed before as you state and also as the awc suppressed model. So i may be wrong about the 634 so don't take it as gospel. the one that was for sale was listed as a 634 upper and i have seen reference to the 634 as a suppressed model though i cant find it at the moment. So i may be wrong about that designation but would like to find out for sure.

Do you have a specific source for the 636 number?  I can only find 2 references to an RO636 online, one as the caption to an artwork of DEA agents, and another from the Michael Connelly book Black Ice.  I don't own a copy of The Black Rifle II, but the much maligned (and rightly so) AR-15/M16 Sourcebook by Duncan Long IIRC has this weapon as the 635S.  I've also heard it just referred to as the "DEA Model."
Link Posted: 11/30/2010 1:22:58 PM EDT
[#42]
Right off the top of my head BR II pg. 271 model list. BR II also has ro634 as semi 635, so at this point im going to say i'm wrong on that one and the upper that was for sale was mis labled.

Whoopie
Link Posted: 11/30/2010 1:23:35 PM EDT
[#43]
I'm at work, so I don't have the BRII here with me.  I don't think it lists it as 636 either.  I think it just calls it a (paraphrasing from memory) "short lived suppressed version that was intended for law enforcement but never really caught on."
Link Posted: 11/30/2010 1:30:42 PM EDT
[#44]
Quoted:
I'm at work, so I don't have the BRII here with me.  I don't think it lists it as 636 either.  I think it just calls it a (paraphrasing from memory) "short lived suppressed version that was intended for law enforcement but never really caught on."


In the text part it doesn't mention a model # but on the model list page it has it listed and states KAC silencer  for muzzle device and special long for hand guard. although BR II has a few inconsistency's I will take it over anything Duncan long has written any day.

Edit: reading the model list page it also list an RO630 has 7" barrel, clamp on front sight and free float handguard. this may be what the pic calls the RO663.

Whoopie
Link Posted: 11/30/2010 2:59:16 PM EDT
[#45]
Quoted:
Edit: reading the model list page it also list an RO630 has 7" barrel, clamp on front sight and free float handguard. this may be what the pic calls the RO663.

Whoopie

This makes me wonder whether there is overlap in the usage of numbers between the 630 and RO630 like there is for the 639.  If the USAF bought replacement GAU-5A/As during the 1980s, this would also explain the appearance of the 649 model number.

I'm starting to wonder whether the prefix letters actually appeared in the 1970s, along with the Carter administration restrictions that led to the NFA classification of the 4" moderator.  This would create a more reasonable timeline for an overlap between the 630 and the RO630, since its generally suggested that Colt effectively dropped the 639 from the catalog and replaced it with the 733 as a result of the moderator issue.  This then freed up the number to be used with the prefix for the 9mm S-1-3 SMG.  This might also suggest that GAU-5A/As with the A1 flash hider instead of the moderator might well have been actual factory weapons, rather than rebuilds.

The collection at the Springfield Armory National Historic Site for instance includes this weapon, marked as GAU-5/A, but said to be a 649 in the collection's notes:



Has what appears to be 11.5-13" barrel.
Link Posted: 11/30/2010 3:19:55 PM EDT
[#46]
Quoted:
Whats the issue?  There's nothing special about it.

Aluminum Barrel Nut

http://media.midwayusa.com/ProductImages/Large/748/748354.jpg


That's interesting...Is it internally threaded to screw on to the upper??? And the handguard screws onto this???  

Seems complicated...Why not just thread the handguard internally, like Mark did...  
Link Posted: 11/30/2010 3:30:52 PM EDT
[#47]
Quoted:
Quoted:
Whats the issue?  There's nothing special about it.

Aluminum Barrel Nut

http://media.midwayusa.com/ProductImages/Large/748/748354.jpg


That's interesting...Is it internally threaded to screw on to the upper??? And the handguard screws onto this???  

Seems complicated...Why not just thread the handguard internally, like Mark did...  


Cheaper parts, labor and tooling?  You could now make the handguards from 3" extruded tubes, instead of solid blocks.  And use as much solid aluminum for 1 handguard to make several barrel nuts?
Link Posted: 11/30/2010 3:51:28 PM EDT
[#48]
Quoted:
Quoted:
Quoted:
Whats the issue?  There's nothing special about it.

Aluminum Barrel Nut

http://media.midwayusa.com/ProductImages/Large/748/748354.jpg


That's interesting...Is it internally threaded to screw on to the upper??? And the handguard screws onto this???  

Seems complicated...Why not just thread the handguard internally, like Mark did...  


Cheaper parts, labor and tooling?  You could now make the handguards from 3" extruded tubes, instead of solid blocks.  And use as much solid aluminum for 1 handguard to make several barrel nuts?


also for indexing the hand guard due to variances in rec. threads and barrel sholuder thickness. when mark cuts the sling slots on the hand guard it needs to be on the upper and barrel its going to be used with or shims to index the sling slots will have to be used. I ran into this on my 636 and wanted to put it on a gray upper and lower but the suppressor barrel nut would not index right with out the use of shims.

Link Posted: 11/30/2010 3:57:29 PM EDT
[#49]
Quoted:
also for indexing...


Exactly...That aluminum nut will have to be indexed to fit the gas tube (on other than 9mm uppers)...and unless it's exactly on, it will be loose or tight...and aluminum is not very forgiving for tight threads...  

Not an issue on Mark's handguard...
Link Posted: 11/30/2010 3:59:41 PM EDT
[#50]
The sling slots and flutes will be where they end up once the HG is tightened down on the barrel. If you look at the picture neither the flutes or the slots appear to be indexed symmetrically.
Also, pics of more progress.


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