You can shoot brush or trees with any caliber for that matter but it's better to shoot the deer.A brush gun should be defined as a short handy firearm, accurate enough for short to medium range and light in weight for prolonged slithering in the thick stuff.A 30-30 fits the bill as does many others.My personal favorite is a 6.5x55 with handloaded 160gr Hornadys.Penetrates deer completely reguardless of angle and moose broadside.Never have recovered a bullet.Just my take..................Harold