M16A1 Lower without Pivot Pin Drain Hole?

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[ARCHIVED THREAD] - M16A1 Lower without Pivot Pin Drain Hole?

Posted: 4/25/2012 7:00:10 AM EDT

Has anyone seen / noticed Colt M16A1 lowers *without* the pivot pin spring channel drain hole?

I was looking over pictures of the MK 12 MOD 0 SPR (built by NSWC-Crane on refurbished M16A1 lowers) and noticed this:

Please try to ignore all the rails and spray paint, and just focus on the A1 lower - I know I've got a picture of the other side, but I'll need to pull it from my other computer, however, it was marked with the earlier M16A1 rollmarks that say "AR-15" as well as M16A1. I can probably get the serial number off the photo as well.

Has anyone seen this before? The mag fence also looks "flatter," kind of like the early M16A2 lower forgings.

~Augee

Posted: 4/25/2012 8:09:08 AM EDT

[#1]

You mean the hole in the side of the fence? I always thought it was to assist in dis/assembly. Yeah that one is missing, and the rear and square part of the fence does look flatter.

I have not noticed this before. Could it just be wear and tear (the flat issue) and a heavy paint job (the missing pinhole)?

Posted: 4/25/2012 8:42:37 AM EDT

[#2]

Quoted:
Has anyone seen / noticed Colt M16A1 lowers *without* the pivot pin spring channel drain hole?

I was looking over pictures of the MK 12 MOD 0 SPR (built by NSWC-Crane on refurbished M16A1 lowers) and noticed this:

http://i1239.photobucket.com/albums/ff502/augeekim/DSC00289.jpg

Please try to ignore all the rails and spray paint, and just focus on the A1 lower - I know I've got a picture of the other side, but I'll need to pull it from my other computer, however, it was marked with the earlier M16A1 rollmarks that say "AR-15" as well as M16A1. I can probably get the serial number off the photo as well.

http://photos.imageevent.com/willyp/firearmsalbums/pendingwork/Mkg%20Early%20Colt%20M16A1.jpg

Has anyone seen this before? The mag fence also looks "flatter," kind of like the early M16A2 lower forgings.

~Augee

The drain hole was an add on at some point during Vietnam to drain water and as an oiling point. Armorers were directed to drill the hole on the ones that didn't have it. Looks like this one slipped past it.

Here is the info from the TM

Posted: 4/25/2012 9:10:39 AM EDT

[#3]

Quoted:

Quoted:
Has anyone seen / noticed Colt M16A1 lowers *without* the pivot pin spring channel drain hole?

I was looking over pictures of the MK 12 MOD 0 SPR (built by NSWC-Crane on refurbished M16A1 lowers) and noticed this:

http://i1239.photobucket.com/albums/ff502/augeekim/DSC00289.jpg

Please try to ignore all the rails and spray paint, and just focus on the A1 lower - I know I've got a picture of the other side, but I'll need to pull it from my other computer, however, it was marked with the earlier M16A1 rollmarks that say "AR-15" as well as M16A1. I can probably get the serial number off the photo as well.

http://photos.imageevent.com/willyp/firearmsalbums/pendingwork/Mkg%20Early%20Colt%20M16A1.jpg

Has anyone seen this before? The mag fence also looks "flatter," kind of like the early M16A2 lower forgings.

~Augee

The drain hole was an add on at some point during Vietnam to drain water and as an oiling point. Armorers were directed to drill the hole on the ones that didn't have it. Looks like this one slipped past it.

Here is the info from the TM

http://i603.photobucket.com/albums/tt118/fortis120/drain.jpg

PS, the TM is dated Feb 1972

Posted: 4/25/2012 10:37:00 AM EDT

[#4]

Quoted:

Quoted:
Has anyone seen / noticed Colt M16A1 lowers *without* the pivot pin spring channel drain hole?

I was looking over pictures of the MK 12 MOD 0 SPR (built by NSWC-Crane on refurbished M16A1 lowers) and noticed this:

http://i1239.photobucket.com/albums/ff502/augeekim/DSC00289.jpg

Please try to ignore all the rails and spray paint, and just focus on the A1 lower - I know I've got a picture of the other side, but I'll need to pull it from my other computer, however, it was marked with the earlier M16A1 rollmarks that say "AR-15" as well as M16A1. I can probably get the serial number off the photo as well.

http://photos.imageevent.com/willyp/firearmsalbums/pendingwork/Mkg%20Early%20Colt%20M16A1.jpg

Has anyone seen this before? The mag fence also looks "flatter," kind of like the early M16A2 lower forgings.

~Augee

The drain hole was an add on at some point during Vietnam to drain water and as an oiling point. Armorers were directed to drill the hole on the ones that didn't have it. Looks like this one slipped past it.

Here is the info from the TM

http://i603.photobucket.com/albums/tt118/fortis120/drain.jpg

Awesome! I knew someone would have the answer!

Knowing that, I would bet, as this lower didn't have any rebuild stamps that I recall, it might have been a Navy or otherwise rarely / lightly used weapon, and may never have made it to Vietnam in the first place and probably sat around mothballed basically new until Crane got a hold of it to build MK 12s and MK 18s.

Interesting new "lease on life" for these old retro rifles - sucks that they're getting broken up - but a lot of these lowers, formerly "obsolete" are showing up on "higher speed" specialty weapons - certainly settles the argument about whether there's anything inherently bad about the A1 lower without the A2 reinforcements!

Regarding the "flat sided" magazine fence, I've seen a lot of those on early A2 lower forgings, I just never noticed them on an A1. I wonder now, how common it was?

Actually, I've found that the PWA lower matches that forging exactly, with the undrilled hole and flat sided magazine fence! Which puts me in a retro / clone builder's dilema, here: do I look for a PWA lower so I have the exact forging? Or do I wait for an NDS so that I can have Ident engrave the right markings?!

~Augee

Posted: 4/25/2012 10:38:49 AM EDT

[#5]

colt made some rifles for the civilian market that used the normal sized pivot pin except it had a screw head like the SP1 therefore it didn't have the spring or detent for that. not the case here since it's select fire.

Posted: 4/25/2012 12:33:11 PM EDT

[#6]

Quoted:
The drain hole was an add on at some point during Vietnam to drain water and as an oiling point. Armorers were directed to drill the hole on the ones that didn't have it. Looks like this one slipped past it.
Here is the info from the TM
http://i603.photobucket.com/albums/tt118/fortis120/drain.jpg

Looking at this page, I wonder about the concern about drilling all the way through into the "INNER WALL OF THE SPRING CAVITY" I would think it wouldn't make much difference going all the way through into the magwell.

Posted: 4/25/2012 12:59:01 PM EDT

[#7]

Yeah. Really great info.

Drain-hole or no never registered with me. Always assumed they were there from the get-go. Wonder when the fence drain hole entered production on the Colt assembly line? Before or after the tech document ?

"I wonder about the concern about drilling all the way through into the "INNER WALL OF THE SPRING CAVITY"" Thinking the same thing.

Caution: Excercise extreme caution when drilling hole that penetration is not made in inner wall of spring cavity. (See Table 3-1)

Wonder what is in table 3-1

Posted: 4/25/2012 1:12:22 PM EDT

[#8]

I'll have to refer to Nickys 1966 TM manual,but IIRC all XM16E1s/M16A1s up to that point (1966) did not have the hole from the factory.It was added as said above by Fortis. The addition was sometime between 1966 and 1967. I will need to double check that date,so please don't take that info as dead balls accurate just yet.

Posted: 4/25/2012 2:46:01 PM EDT

[#9]

Quoted:
Yeah. Really great info.

Drain-hole or no never registered with me. Always assumed they were there from the get-go. Wonder when the fence drain hole entered production on the Colt assembly line? Before or after the tech document ?

"I wonder about the concern about drilling all the way through into the "INNER WALL OF THE SPRING CAVITY"" Thinking the same thing.

Caution: Excercise extreme caution when drilling hole that penetration is not made in inner wall of spring cavity. (See Table 3-1)

Wonder what is in table 3-1

I think the concern about over drilling was some over zealous Armorer may drill all the way into the mag well and possibly cause burring, mag fit issues.

Here is table 3-1

Posted: 4/25/2012 5:46:43 PM EDT

[#10]

Ok,just off the fone with Nick.The 1st time the hole shows up is in the 1968 manual. This is not to say some late 67s didn't have them.

Posted: 4/25/2012 6:02:43 PM EDT

[#11]

Fortis can you show Fig 3-9 on stock repair. Have a few surplus stocks that appear to have been field repaired at some time. Wondering what the proceedure was in figure 3-9? Most just look like JB weld dyed over to me. Thanks for sharing pics Augee. Never really looked at many A-2 FA's for flatish fence or drain hole.

Posted: 4/25/2012 6:16:42 PM EDT

[#12]

Quoted:
Fortis can you show Fig 3-9 on stock repair. Have a few surplus stocks that appear to have been field repaired at some time. Wondering what the proceedure was in figure 3-9? Most just look like JB weld dyed over to me. Thanks for sharing pics Augee. Never really looked at many A-2 FA's for flatish fence or drain hole.

i have some repairs that look like whitish jb weld and some that are greyish. some have a cloth patch like pattern too.

Posted: 4/25/2012 7:06:24 PM EDT

[#13]

I can just see it now - guys smashing the crap out of their stocks, then using JB weld to fix them and to plug the detent hole in the magfence to make it 'more accurate historically' on a BTDT build.

You friggin' guys are really out of control.

Posted: 4/25/2012 7:51:18 PM EDT

[#14]

Quoted:
I can just see it now - guys smashing the crap out of their stocks, then using JB weld to fix them and to plug the detent hole in the magfence to make it 'more accurate historically' on a BTDT build.

You friggin' guys are really out of control.

What, me?

~Augee

Posted: 4/25/2012 7:53:37 PM EDT

[#15]

Fortis

Never call a Small Arms Repairman an "armorer".
Them's fightin words.

Posted: 4/25/2012 8:03:07 PM EDT

[#16]

Quoted:
I can just see it now - guys smashing the crap out of their stocks, then using JB weld to fix them and to plug the detent hole in the magfence to make it 'more accurate historically' on a BTDT build.

You friggin' guys are really out of control.

Not me. I'm moving on...

Posted: 4/25/2012 8:37:46 PM EDT

[#17]

I like this post by nobar60 showing his XM16E1 with no hole drilled:

http://www.ar15.com/archive/topic.html?b=3&f=123&t=527014

I made a partial fence lower the "wrong way" by filing down and having a friend weld up the right side markings and drain hole of an A2 lower receiver. Gray is Norrell's, I need to re-park some things.

ETA: NDS has some 0% full fence forgings so you could make a replica without welding or re-profiling an A2 lower.

Posted: 4/25/2012 9:52:22 PM EDT

[#18]

In the early days of this forum, before NDS blessed us with their presence, the '2nd stage' of building retros was either doing an 80% or reprofiling an A2 to A1 specs. No one gave anyone a hard time about A2 lowers on their build because EVERYONE had A2 lowers, other than a few SP1 builds and some lucky bastards with happy switch weapons. I have quite a bit of fabricating experience, but I am still in awe of those brave souls who grind their way into the pages of this forum. I like to razz people (It's genetic) but damn boys, you folks make me feel like I'm not pulling my weight. I intend to change this soon, but dammit, you are such a talented group of individuals, it's hard to stand tall next to you. I'm constantly impressed by the skill level and determination of members of this forum. Why spend $45 to buy a Magpul stock when you can spend $250 to build a 608 yourself? (UncleMoak will probably correct me on that - where the hell is he anyway?) Anyway, Drive on!

Posted: 4/26/2012 2:39:17 AM EDT

[#19]

Quoted:
In the early days of this forum, before NDS blessed us with their presence, the '2nd stage' of building retros was either doing an 80% or reprofiling an A2 to A1 specs. No one gave anyone a hard time about A2 lowers on their build because EVERYONE had A2 lowers, other than a few SP1 builds and some lucky bastards with happy switch weapons. I have quite a bit of fabricating experience, but I am still in awe of those brave souls who grind their way into the pages of this forum. I like to razz people (It's genetic) but damn boys, you folks make me feel like I'm not pulling my weight. I intend to change this soon, but dammit, you are such a talented group of individuals, it's hard to stand tall next to you. I'm constantly impressed by the skill level and determination of members of this forum. Why spend $45 to buy a Magpul stock when you can spend $250 to build a 608 yourself? (UncleMoak will probably correct me on that - where the hell is he anyway?) Anyway, Drive on!

Yap,yap,yap,,,slacker...Get off your arse and show us what you can do.

Hell,,even Gunner pitched in with his damn fine "tool"

< Somehow dat just don't sound right...

Posted: 4/26/2012 3:11:54 AM EDT

[#20]

Quoted:
Fortis

Never call a Small Arms Repairman an "armorer".
Them's fightin words.

I did that for the masses. How does Combat Arms Training and Maintenance (CATM) sound?

Posted: 4/26/2012 3:15:27 AM EDT

[#21]

Quoted:
Fortis can you show Fig 3-9 on stock repair. Have a few surplus stocks that appear to have been field repaired at some time. Wondering what the proceedure was in figure 3-9? Most just look like JB weld dyed over to me. Thanks for sharing pics Augee. Never really looked at many A-2 FA's for flatish fence or drain hole.

Fig 3-9 is on the same page as the drain hole drawing (see the top of this post)

Posted: 4/26/2012 4:51:28 AM EDT

[#22]

Quoted:
In the early days of this forum, before NDS blessed us with their presence, the '2nd stage' of building retros was either doing an 80% or reprofiling an A2 to A1 specs. No one gave anyone a hard time about A2 lowers on their build because EVERYONE had A2 lowers, other than a few SP1 builds and some lucky bastards with happy switch weapons. I have quite a bit of fabricating experience, but I am still in awe of those brave souls who grind their way into the pages of this forum. I like to razz people (It's genetic) but damn boys, you folks make me feel like I'm not pulling my weight. I intend to change this soon, but dammit, you are such a talented group of individuals, it's hard to stand tall next to you. I'm constantly impressed by the skill level and determination of members of this forum. Why spend $45 to buy a Magpul stock when you can spend $250 to build a 608 yourself? (UncleMoak will probably correct me on that - where the hell is he anyway?) Anyway, Drive on!

I remember those days!

Getting a PWA forged A1 lower was a major coup! Actually, they were the most expensive part, because you had to compete with all the "preban" guys to get one!

I had one early on - when NDS started selling their retro-lowers, I actually traded a ban state guy two stripped NDS lowers, and money for LPKs for my PWA! (This amounted to about $350 for a complete preban lower at the time - so I didn't "gouge" on the preban, either!)

~Augee

Posted: 4/26/2012 10:04:08 AM EDT

[#23]

Fig 3-9 is on the same page as the drain hole drawing (see the top of this post)

Went right by it. Tough going blind. Should have stopped when I just needed glasses. Joke! Any mention of field/armorer preceedure or did I miss that too? Always thought it was some pretty tough epoxy and TM pics kinda confirm my suspicions. Have seen some real nice jobs and some not so nice jobs but stuff doesn't seem to sand very well once it's set. Guess I'll dig up some old TM's and take a look. Probably a market for the old beater stocks now. I was always scared to sell them and just use them on my personal shooters for that budget sleeper look.

Posted: 4/26/2012 2:07:54 PM EDT

[#24]

Going back through TBR and some other docs I do see that partial fence lowers do not show a drain hole in period images. Also looks like full fence had the hole from the get-go (?) not sure about that.

Posted: 4/26/2012 2:42:23 PM EDT

[#25]

If you re-read what I wrote above,,the hole shows up for the 1st time in the 1968 manual TM9-1005-249-34 Dated Aug 1968, which would mean all partial and full fences up to approximately 1968 would NOT have had the hole from the factory.
There is always a slight chance that a late partial or an early full did get drilled at the factory.
ETA,hope this doesn't get to confusing,,but here we go. That 68 manual above has printed in it that it "supercedes" the 1966 manual..Nick has the 66 manual and that manual has an "addendum" (am I using the correct word) dated Jan 1967. He does not have a 67 manual,,BUT going but the statement printed in the 68 manual "supercedes" the 66 one,,there may not have been a 67 dated manual????? The late 66 one with the addendum may have been used for 67.

Posted: 4/26/2012 5:14:43 PM EDT

[#26]

Yeah, I missed that part of your post. Interesting thread. Hats off to the OP

Posted: 5/2/2012 9:42:30 PM EDT

[#27]

I would like to ask mike_nds and / or HarlanNDS if they would consider making the NDS-XM16E1 lower receiver without the drain hole. Everyone would benefit, production would be simplified & costs would go down, existing lowers with the hole would become collector items, people with drain hole lowers would buy the new ones so they could have one without the drain hole.

what do you think? (should we take a poll? How do you do that here?)