"Solid hits" may or may not put a deer on the ground, regardless of the caliber or cartridge. I've seen quite a few deer hit in the ribs that went a long way. It boils down to shot placement, and then exactly how the bullet moves through the animal and what it hits along the way. A deer can't tell you whether the .308", 150 gr. projectile that just hit it was fired at 2200 fps (30/30)or 2700 fps (308 Win).

A 30/30 will always be more than adequate for deer out to 150 yds, powerwise. I'll bet that a good percentage of deer lost that were shot with a 30/30 are due to limitations inherent to the aiming system. May 30/30's are iron sighted guns, which for me at least, are more difficult to aim precisely in comparison to a scope. Irons are awesome out to 50 yds for me. But the white bead on the front sight of my Win 94 covers a lot of area at 100 yds. So, a hunter may swear he hit the deer "right in the boiler works" but actually made a marginal hit.