the m6g, if it feels a little big for your hads from the hilt of the gun then its too big, if not then its not big at all. if u feel comfortable holding that then its a no biggie. but to me, they seem a wee bit big, like a one or two centimeters too big for me, in my opinion.
the helm on the other hand, is just perfect to me...again in my opinion, because once u fiberglass that thing, its gonna be hard getting in and out, i learned that the hard way, and therefore i had to trim it. from the roof of the helm, to your scalp should be a good inch. and furthermore, if ur going to fiberglass it, glue on the visor part or else the whole thing will warp.
again, in my OPINION