duplicating Colt gray/green from the late '80s

[jaygee]

Many of you will remember the Colt Gov't model 6550 from around
1987 or so. The uppers and lowers were finished in a green shade
that came very close to duplicating the steel park job on the barrel
and other steel parts. I'd like to apply such a finish to an A2 style
lower I'm using on an A2 build. What would come closest to getting
me in that direction.

[ZRH]

You can vary the shade of anodizing by adding various acids to the electrolyte solution and changing the voltage. Then it gets sealed in water or with a finish like teflon. This is why some anodizing jobs end up grey or black or purple. The thing is though that you cant change it when it's done (except by carefully removing the old anodizing which is usually cost prohibitive and you lose the top .001" of metal).

The original Sporters also reportedly had green aluminum extension tubes. I've never seen one though.

[jaygee]

I'm actually thinking about an external type coating, such as Duracote
for this job....something that could be removed if absolutely necessary. Re-anodizing would be a possible option if I was 100%
sure it would match my other parts....pretty tough, so that would be
my last choice.

[CAR]

Sandstrom 9A is not the gray finish used on Colt AR-15s. They are anodized in that color.

[ZRH]

Good call I totally forgot about that. Sandstrom 9A was used to refinish stuff for the military at some point I know for sure. It's a good match -.- The grey color is greenish. http://www.sandstromproducts.com/gun...t-coating.html

[Col_Crocs]

Thanks for the link!
Anyone with experience and knowledge on this stuff?
Im curious as to why the 9A was chosen over the 859 back then. Was the 9A the only one available at the time or does its surface durability(mar resistance) actually compare to that of the 859's with the added benefit of lubricity?

[ZRH]

I don't think that's what they used at the factory but it colour matches pretty well. In TM 9-1005-319-23&P on page 8-2:

Solid film lubricant (SFL) is the authorized touch up for the M16A2, M16A3, and
M16A4 Rifle and M4/M4A1 Carbine and may be used on up to one third of the
exterior finish of the weapon.

FOR ARMY CONUS USE ONLY AND AIR FORCE TRAINING WEAPONS ONLY:
Solid film lubricant may be used as a touch up without limitation on the upper
receiver and barrel assembly. Units which DO NOT fall under the category of
Divisional Combat Units or rapid deployment type units may have up to 100 percent
of the exterior surface of the upper receiver and barrel assembly protected with SFL.
Prior to application of SFL, the surface must be thoroughly cleaned and inspected for
corrosion and/or damage. If corroded or damaged, the part must be repaired or
replaced prior to application of SFL. Continued use under combat conditions would
result in an unprotected surface when the SFL wears off. This would result in a
large light reflecting surface and accelerated deterioration of the unprotected surface.
Therefore, Divisional Combat Units and units which fall under the definition of
Rapid Deployment type must adhere to the limitation of NOT over one third of their
exterior surface covered by SFL.

Then SFL is MIL-L-23398 which is Sandstrom 238 among others, which described on their website as:

Air Dry solid film lubricant used for parts too large to be baked or parts that cannot be subjected to bake schedules of 9A, 099 and LC-300. Ideal for field touch-up of parts originally coated with 9A, 099 and LC-300.

So essentially 9A is the more heavy duty stuff that you have to bake on. USGI mags also are coated in SFL.

I've used 27A in grey to refinish work surfaces on machinery and it's just like spray paint. Usually the instructions are pretty thorough on this type of stuff.

[ZRH]

If you have in the white parts: these guys do a good job anodizing. http://www.usanodizing.com/colorchart.htm#ATypeIII

[jaygee]

I have two lowers actually, that need to be considered here. Both,
1 Bushie, 1 Colt, are finished in the current near black coating. The
Bushie would be OK in the older gray finish, but the Colt wants to
be the green stuff. A spray on type coating, if it's durable and
chemical proof would be fine here, as I'm not looking for a re-
anodizing at this point.

[Dave_M]

When I made an XM-16E1 clone for my ex's father (he carried one in 68') I had to have the lower custom modded so it would have a partial fence.

Anywho, AHII in parkerizing gray matched great. However, it wasn't exactly the instructions on the package:
-Prep metal (I bead-blasted with aluminum oxide)
-Degrease
-Heat metal
-Apply as directions state
-Bake it for 5.5 hours at 180-200 degrees (I find baked AHII to be far tougher than the air-cured)
-After baking, while the metal is still wet, slick it all down with some CLP.

Color came out perfect


It's that perfect vintage 'Colt gray/green' color. Looks more gray in the pic but it really does have that green tinge to it