Typically lead bullets are sized 0.001" larger than groove dia. Berry's are pretty much pure lead /w a thin plating, so they are meant to be loaded like a lead bullet, often you will see them 0.001" larger than jacketed.
"Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified".