Hello,

Does anyone know conclusively what the original Colt triangle hand-guards were made from? The butt stock is definitely some form of composite; I can see that clearly when I look inside the storage chamber; its a kind of yellowish-gold resin.

People on-line often make bold statements in absence of any actual knowledge, and many of them say that they are actually made of fiberglass. But mine seem far too thin and light to be glass-fabric bedded inside gel-coat. Are we sure that they aren't just plastic?

My AR is an early 80' vintage NIB, and as such the hand guards are unmarked and matte black, and therefore give nothing away regarding their underlying composition. I want to 'improve' their finish because they look like they were finished by a chimpanzee with sputtering rattle can.

Please advise.

Timothy St. John

The very early proto-types were glass fibers in an epoxy matrix, the glass fibers are quite visible.

The later ones are glass fiber reinforced plastic, either Fiberite FM-7700, FM-3510, or Rogers RX475, initially semi-gloss finish due to the molding process, later matt.  The glass fibers are mixed into the plastic resin prior to pressure molding.

The butt stock is is an assembly, the shell is the the same glass fiber reinforced plastic the inside (the yellow stuff) is a separate plastic piece epoxied in place, and between the two is foam for rigidity, the complete assembly is epoxied together.

Hello,

Genius! Thank-you very much. That is far greater return than I could have hoped for. It can be very difficult sorting through this huge resource. All posts are in earnest, but its hard to tell which ones have actual authority behind them.

Do you know, were they then painted, or coated some how, or is the black just a property of a colored resin? I wonder...would a light sanding with 400-600 grit, disturb and expose the glass filaments, so as to reveal them, or are they far enough beneath the surface to suffer a polishing? Thanks again!

Timothy St. John

As manufactured they were not painted, the plastic is just black.

I do not know if painting them was ever officially authorized as a way to refinish/refurbish them.

Oh, and a few things I was mistaken on . . . .

- All of these plastics are classed as phenolics.
- FM3150 and RX475 are fiber reinforced, and the reinforcing material is cellulose, not glass.
- FM7700 is not listed as having a reinforcing fibers.
- This is only true for original production triangle handguards, those made after the Army stopped buying them made be made from other plastics.

Sir,

I am in your debt. Your replies were military in response: accurate, precise, succinct, as requested, on-point, and on-time. Normally one would have to suffer all kinds of irrelevant abstractions to secure that much relevant and pertinent data on another sight. Thank-you!

Timothy St. John

Hi again,

I looked up the Bakelite, and found, among many other interesting facts, this forumla for FM7700. It is described as: FM 7700P is a two-stage phenolic molding compound reinforced with cotton fabric in pellet form. FM-7700P is recommended to customers desiring approval under ASTM D-5948-96,Type CFI-20. (Replaces Military Specification MIL-M-14H.) Here is the sight information: http://www.matweb.com/search/datasheettext.aspx?matguid=881fb446f0f047278efd6c9e455ed844

I know it's not very tactical, and I apologize to anyone whose tastes and service from this rifle run in that direction, but I want this AR to look as little threatening as possible when I take it to the range. To that end, I've already ordered a walnut set of Matt Shuster's beautiful wooden furniture from his "Ironwood Designs". If you haven't checked Matt's stuff out you really should give it a look as...http://ironwooddesigns.com/IWDHome.html . Until then, I would like to play with the stock furniture while I wait.

Bakelite polishes up beautifully with Brasso, or other mild abrasive and a buffing wheel (or elbow grease). There are lots of videos on refurbishing Bakelite products on YouTube; especially old radio cabinets and electrical switches. Nothing on AR handguards though, and maybe there is a reason for that beyond the mere aesthetic principles involved. If you have any advice I would love to learn by the member's experience.

In the mean time, I'll figure out how to imbed links properly, so that those of you who are kind enough to follow my thread don't have to copy and paste to explore the material. Sorry about that. The rest of you are so good about that and I aspire to return that courtesy.

Tim

we have a retro forum

http://www.ar15.com/forums/f_3/123_AR_15___M_16_Retro_Forum.html

FM7700P is not the same as FM7700.

The "P" as you noted indicates the addition of cellulose fibers.

Hello,

Thanks very much for your help. I'll try the retro forum instead. I can imagine how frustrating it must be when newbee's keep posting the same old tired questions. You've all been very patient. My questions were spawned by poor exercise of the sight's search engine, which limits non-paid members access to its data base.

But , I did just access some good threads pertaining to the subject matter that concerns me, once I learned how to access the forum through Google instead of the sight's own search engine, so I'll be reading for a good while before my next post.

AR15.com Is a great resource, but more importantly, as a site, it doesn't seem to be choked down with members who seem to think that it is their job to suss out or prank posters. On other sites such individuals attach smart-ass, derogatory, or inflammatory comments to every earnest and innocent post. Is that what a 'troll' is?

Anyway, the result is that by your conduct you commend membership. I am sufficiently motivated by the responses that I've received here to pursue becoming a paid member. That's how these sites are supposed to work: one convert at a time. Its been a pleasure gentlemen!

Timothy St. John

P.S. My problem is I'm interested in everything. Today I'm fascinated by Bakelite, last week it was a necessary interest in organic chemistry, and before that fluid dynamics. But not in a passing way, my curiosity is ongoing. The day just isn't long enough.

Being a paid member has some search benefits. I was a "free" member for a couple of months before I decided this site had excellent technical info. I even made some friend via the Hometown Forum area for my state. I stay out of the General Discussion area because I deal with enough stupidity in real life I don't need it after work. My motivation for joining was to support a site that has helped me learn.

I can tell you this the paid member search still is not terrific. I use Google to search the site.