I have 7mm bar spacing on Charlie's Savic Mickey 2XL. He was very nervous when he was a baby and hated the scraping noise of the bottle going through the bars, so I used a bottle stand inside the cage and am now using this Ferplast Drinky 75ml bottle which has a clip that clips to the inside of the bars - works well if you're interested.
Fpi 4660 Drinky75 Drinky B.