I used a 30-30 last year. I killed a 4 point w/ it. I shot it right in the heart. and the bullet didn't make it all the way through the deer. We found it in three peices. So I personally don't trust them w/ big bucks. But they are good guns.
I didn't get a pass-thru on the big buck pictured above either, but he only went 40yrds. If the bullet makes mush of the heart/lungs the deer won't go far. Tubular magazines require a flat nosed bullet, not good for long range, but great for dumping all their energy in the target.
I don't hesitate to take the 30-30 for big Canadian deer.