Only your rifle barrel knows that answer. It depends on the rifle make, the barrel length, and the design of the projectile also. Some of my inlines like large heavy bullets and sabot combinations, while others seem more then happy with a 240 grain class. I found the 250 and 300 grain are the best shooters for the most part in any of the inline rifles. Yet some of them will shoot about anything you stuff down them. My Black Diamond XR for instance will shoot a 200 grain Shockwave with excellent results. It will also shoot a 405 grain Remington FP with great accuracy as well. Only your rifle will answer that. What kind if rifle are you shooting? Perhaps the forum could offer some suggestions that worked well for them with a similar rifle. Not that it means yours will also shoot the same load well....