Question for you Retro Experts.

[sinlessorrow]

So a question for all you experts on retro AR-15's and their history.

What made them go from Chrome BCG's to phospated as well as moving from the original firing pin retaining pin to go with the cotter pin?

[halfmoonclip]

The chromed bolt carrier was visible thru' the ejection port; it could show up like a spotlight under the wrong circumstances. The interior of the carrier remains chromed for corrosion resistance.

I'll hazard a guess on the FPRP, tho' I'd have to research it in The Black Rifle.
I think it may well be just a cost thing; the original pin was machined and had to be expensive. There may have been an issue with the ears on the pin breaking off and causing mischief.
Moon