What firearm are you using it on? The more information you can give the better it will help someone trying to answer your question.
Do you mean a Trijicon RMR with a 1 MOA dot reticle? Also I don't quite understand what you mean by "would 7mm be better".
Trijicon says "The best MOA size for hunting depends on the distance and target size. A 1 MOA dot is great for precision shots on small games or at longer ranges. A 3 MOA dot balances accuracy and quick target acquisition for larger games at closer distances."