You're right. The tube is 30mm, the objective lens is 52mm. It is pretty darn bright at dusk and dawn compared to some other scopes I have. I thought about 154 Hornady's but I shoot Remington Core Lock pointed soft point in my other guns with good success, so I'll go that route first. I'm going to bring the gun in next week for a grind to fit Limbsaver pad and a trigger job first. Then try again.