The last "brush-busting" test I recall is from some 30 years back, in The American Rifleman. They tried everything from small stuff moving fast, on up to .45-70. Spire points and round nose, etc.
No bullet shape or weight was better than any other bullet shape or weight. (Yes, hot .22s and suchlike do blow up.) The most important variable for "deer cartridges" or larger seemed to be the distance from the twig, stick or limb to the animal.
If the target is right next to a clump of brush and you shoot through it, you have good odds of a hit. If the distance from the brush to the animal on the other side is five feet or more, you're gonna be real lucky if anything good happens.
"Brush-busting" bullets is strictly hype, when the shape of the nose of the bullet is the selling point. A 220-grain round-nose bullet in 30-caliber will deflect just as happily as a 150-grain spire point. A .45-70 bullet will deflect just as badly as a .308...