Lowers: teflon over anodizing vs. just anodized
I did a couple searches and couldn't find an answer to this question, so here goes.
A few manufacturers of lower receivers advertise that they do class III anodizing and then apply teflon over it. The ones I know of are DPMS, CMMG, Charles Daly Defense, and DoubleStar. It appears that Spike's Tactical makes some but not all of its lowers this way also.
In addition, I've read comments about Mega lowers having this teflon coating, but have not seen it advertised by Mega or their distributers.
Virtually all the other manufacturers say only that they do class III anodizing (some of them will go further and say class III, type 2, military spec) without any mention of teflon coating. I am guessing that the military spec does not call for teflon and that manufacturers following it, such as the high quality Colt, DD, BCM etc. do not do teflon. But I'm only guessing.
Can someone tell me:
1) Is the teflon over anodizing only done by the listed few above? I ask partly because a post somewhere else said that the teflon was a standard post-anodizing treatment, which makes me wonder if it's done on most/all but only advertised by a few.
2) If teflon is not done by most, why not? It seems like it adds durability and corrosion resistance even beyond what you get from the hard anodizing. Does it create any issues with retaining rollpins in place?
3) I have a Charles Daly Defense lower and their finish looks different from the other companies advertising teflon (DPMS and CMMG in particular) and seems more durable than any other lower finish I've seen. And I've read comments from others to this effect. CDD is out of business and their lowers are basically off the market now. Does anyone else make a lower with the same finish?
4) If anyone knows, are the Mega-branded lowers teflon coated or not?