Judge, about paint or coating over the fiberglass of handguards, sorry to be dense. I thought you were talking about something like this
You mention "why would anyone paint them if they were not painted from A-I originally?" The after factory paint shown on the rifle above is something I have seen often enough to know folks have done it.
The collector friend who sold me my Portuguese rifle bought two sets of horribly repainted Sudanese handguards at a western gun show a few years back. One set was orange red, the other a more intense green than the set above. My guess as to why anybody would repaint a set is to arrest further degradation of a handguard.
Here's some examples of Sudanese furniture in stages of degradation.
Actually, with the Sudanese rifle we're dealing with a one piece handguard, a tube really, so I will try to refer to it as a handguard. You were wiser to use the term fore end instead

The Portuguese rifle has two piece handguards so plural is appropriate.
You mention you have one red buttstock without paint yet you have a fore end with paint. This isn't consistant to me.
Every factory original Sudanese set of furniture I've seen have a buttstock, handguard, and pistol grip with identical finish. So they should have the same shade of coating, which of course has to be some type of paint, again sorry to have been dense. They might vary between semi matte and semi shiny but the pieces should be consistant to each other from the factory. The set on mine in the picture with 2 operator's manuals tends toward shiny. I'd rate the condition as a strong 90%
It's interesting to note that this is not the case with Portugese furniture. The Portugese handguards always have a different finish and color to them than the butt stocks, which are darker. Their pistol grips may match the buttstock or they may be mottled but similar dark color as the buttstocks, giving rifles "3 shade furniture".
Here's some examples of a two different Sudanese rifles. One of them is actually a near mint fully transferable one. Too bad I don't have 30K + to get one like it.
This last example has a stock set very similar to my rifle's as far as shine but mine are a bit darker.
I appreciate your experiences with the Sudan Army unit discs.
Lets go with this for a bit. Sudan Army unit discs may be comparable to rack numbers on US infantry rifles. I think Sudan probably did request A.I. make the discs for them even though even poor Sudan could easily have made their own. A.I. would most decidedly not have engraved the Sudan/Arabic units on the discs. First of all Sudan would not have sent a list of their units to another country. They would engrave them at home, an easy thing to do, like a rack nunber, even though those are paint and not brass discs. We probably won't ever know whether the discs were made in Holland or Sudan. It's no good mentioning that A.I. made the rear sight adj. wheel with Arab characters. There are only 8 symbols required on the sight wheel, one is Arabic, one is a white dot, and 1-6 are numerals which I believe are common to Arabic and universal math. It was an easy task for A.I. to use only one Arabic symbol for production. Engraving Arabic symbols that vary from unit to unit is hardly something A.I. would have wanted to do, or perhaps could do unless they had an Arabic speaker in the plant (not impossible, though).
There would never have been an AR-10er magazine if there hadn't been enough interest on the front end. That monthly newsletter didn't boost a lot new collectors into the fold like an ad in Guns and Ammo or the internet would have. It merely kept a small number AR-10 collectors in touch. It is just as possible a disc was made by a collector as it was that it was made at A.I. as a blank replacement disc. We'll never know. Your observation is has merit. I've never encountered a disc with no unit engraving - I will give it more thought. Thanks for sharing that tid-bit.
I mis spoke yesterday when I said there are 3 versions of AR-10 magazines. There are 4 versions.
Here's a picture of 4 variations of AR-10 waffle magazines. From the left to right, Hollywood AR-10 magazine (no tabs), Gray 1st type Sudanese (no tabs), Gray 2nd Sudanese and transitional AR-10 (tabs), and Black Portugese (tabs).
Picture of the 4 magazine variations floor plates. Notice the different fonts and stamping contours
You probably have them, but if you don't have all the The AR-10er newsletters I have all of them on PDF and I'd be happy to make you a disk (or disc

) and send them to you. Let me know if you want them.