In reality there is no such thing as a "brush gun". Any caliber can and will deflect if it hits an object between you and the intended target. Obviously some calibers will do better than others but none will be 100%. I use 130gr Hornady SST's in my .270. Very accurate bullet and has very good expansion and energy transfer. With good shot placement most fall in their tracks and have never had one go more than 50 yards with a really good blood trail. The downside is if it hits any type of a limb it will either deflect horribly or kind of explode. On the other hand, if you opt for a bullet that is much harder it may penetrate brush and limbs but have little or no expansion when it hits the deer. Years ago I tried Barnes X bullets. They were actually intended for much larger game than deer. Entry and exit wounds were identical and I found the heart to be split in half with a small pencil sized hole through the middle. Deer went about 70 yards with lots of blood. Had it not been a dead center heart shot this deer would have likely run forever with no blood trail. Haven't used those bullets since.
This year I will be hunting with a Ruger Super Redhawk 44 magnum using 240gr Hornady XTP bullets in handloads. The area I will be hunting offers no more than a 50 yard shot so only time will tell but this combo seems really good. Hope to find out soon.
Like the others, I would like to know what ammo you are using.