Well, seeing as the guys on the Gun Nuts show just did a an episode on shooting through brush, I can honestly say that the evidence was quite clear.
No round shoots through brush (or even a single branch) reliably.
The bigger the round, the bigger the deflection was what happened. Which means the lighter the round, and faster as well, the less the round deflected.
Which actually sort of proved that the whole "brush gun" theory was backwards at best, but wrong in all reality.
Of course, after having seen that disproved while deer hunting, I had no doubts about the lie of the belief. I've seen bullets in the 30-06 and .44 calibers get deflected by an errant branch or by a group of branches making up a brush pile.
The only queston I have is, do you need a shorter barreled rifle because you still hunt, or do you stand hunt? If you do more stand hunting, go with a .270 or a 308. Well, with any of the more powerful rounds than a 30-30. You can accomplish the same task, and then some, with so many other better rounds out there than a 30-30.
The 30-30 is more of nostalgic hunting round today than the wildly popular hunting round it was in my Grandfather's hunting days. It was still quite popular in my Father's early hunting years as well.