I read a post in a forum that Briskers, apart from following the conventional Yeshivish pronunciation of Hebrew including oy for cholam, pronounce Ayin as a velar nasal. I just want to get this verified if it's right or wrong because I thought that only in the Dutch pronunciation of Hebrew was this found. Also I thought that all haredi misnagdim had the same Yeshivish pronunciation and didn't expect one group to have a variant of the standard Yeshivish pronunciation.
Yes and no.
They don't pronounce it as a NG sound alone. They also don't pronounce it similar to Aleph like most people. They pronounce it as starting like a Ayin but ending with a HALF NG sound. Or at least that is what they are trying to pronounce. They do it that way because the way some Rishonim say an Aiyin is supposed to sound.
I don't remember where the N comes in but I do remember that some Rishonim say that Aiyn is supposed to end like half a Gimmel