I have the APA standard in front of me and I can't see anywhere in it where an ameraucana is disqualified for having a particular color egg. In fact, as far as I can tell, they aren't judged for egg color at all. Chicken shows judge for phenotype. This means that a bird laying a brown egg, could easily be considered the best ameraucana in any given show if it has the best phenotype. When breeding animals, this is a very possible senerio. People who breed for phenotype with no consideration for egg color can easily end up with birds that have good "type" and the wrong egg color.
I have an ameraucana/welsummer cross that lays an egg I would call brown, not olive (I'll post a photo later). The cross has very nice muffs and beard. Color is quite good except for a few brown neck feathers. Legs are not slate grey, but close. Comb is very ameraucana-like. I can imagine with a few more generations of working with these that I could get a showable ameraucana, with brown eggs.
What I'm hoping the OP gets out of this, is that if they are concerned with getting ameraucanas that show true to type, you cannot determine it's show quality by egg color. While it may very well be true that few if any show quality ameraucanas actually have brown eggs, I'll wouldn't bet against it, and believe that we shouldn't be using egg color to determine show quality, unless the standard calls for it.
I have an ameraucana/welsummer cross that lays an egg I would call brown, not olive (I'll post a photo later). The cross has very nice muffs and beard. Color is quite good except for a few brown neck feathers. Legs are not slate grey, but close. Comb is very ameraucana-like. I can imagine with a few more generations of working with these that I could get a showable ameraucana, with brown eggs.
What I'm hoping the OP gets out of this, is that if they are concerned with getting ameraucanas that show true to type, you cannot determine it's show quality by egg color. While it may very well be true that few if any show quality ameraucanas actually have brown eggs, I'll wouldn't bet against it, and believe that we shouldn't be using egg color to determine show quality, unless the standard calls for it.