I have read two opposite theories about bullet stabilization and brush penetration. One suggests a bullet that is highly stable (spinning very rapidly) is more likely to stay pretty much on course after encountering an obstacle than one that is only marginally stable (spinning more slowly). On the other hand, I have also read that a fast spinning bullet is more apt to spin away from any surface it touches, as a billiard ball with a lot of English on it spins away from another ball.

Unfortunately, I cannot say which theory is correct. Among common hunting projectiles, the Foster type rifled slug, which is stabilized by its weight forward balance, is the best brush penetrator and it doesn't spin at all.

I have read about several brush-bucking tests in which the authors tried to empirically determine what sort of bullet is most likely to penetrate brush and reach the target (usually a deer silhouette). The test conditions were all different, ranging from firing bullets at a target placed some distance behind actual heavy brush, to intentionally shooting through limbs, to firing into a box filled with equally spaced wooded dowels of fairly large diameter. (A 500 grain .458 Win. Mag. round nose (RN) "solid" bullet negotiated the latter obstacle course best.)

One important variable in such tests is the distance the target is placed behind the obstructions. Another is the diameter and hardness of the simulated or real brush. A leaf is different from a twig, which is different from a branch, which is different from a rigidly held wooden dowel.

Real brush has a lot to recommend it and is probably the test medium I would choose, but the biggest problem with using real brush is that all bullets cannot hit the same amount of brush at the same angle, randomly skewing the results. I suspect that you would have to fire an awful lot of bullets into real brush to get statistically valid results.

Unfortunately, the results of the tests I have read about varied widely. I have never constructed such a test myself, as I am not sure what the test conditions should be and how to control them. I suspect that the results of my test would be no more reliable than previous tests. Most authorities have concluded that a large caliber bullet of great sectional density gets through brush the best. Cartridges like the .458 Winchester Magnum are frequent winners. This makes sense to me.

Jack O'Connor, in his Gun Book wrote about the results of such a test that he spent several afternoons conducting with a variety of calibers and bullet weights. O'Connor shot at a three foot by four foot outline of a deer through a heavy screen of natural brush. His results indicated several things. One was, as logic suggests, the farther behind the brush the target was placed, the safer it was. At six feet the deer target was liable to be hit somewhere; at 20 feet the deer target was pretty safe.

O'Connor tested a variety of calibers from the .220 Swift to the .375 H&H Magnum, including the standard 12 gauge shotgun rifled slug. The latter projectile proved to the best brush-bucker of them all, as it is stabilized by its weight forward design, rather than by spin. Even the 300 grain bullet fired from the .375 Magnum showed considerable deflection in O'Connor's testing. The .35 Remington's 200 grain RN bullet often found the target, but frequently hit sideways. (Obviously, not a satisfactory result.)

The worst caliber for penetrating brush was the .220 Swift loaded with a 50 grain Spire Point bullet. It almost never made it through the brush intact. No surprise there, as this bullet is designed to break-up against light resistance.

Fairly light (for their caliber) high velocity spitzer bullets, such as the 87 grain .250-3000, 100 grain .257 Roberts, 130 grain .270 Winchester and 150 grain .30-06 also faired poorly in O'Connor's brush tests. The 100 grain .250 bullet was better than the 87 grain bullet, but still not very good at getting through the brush. Compared to the lighter spitzer bullets, the heavier 117 grain RN .257, 150 grain RN .270 and 180 grain RN .30-06 bullets all gave O'Connor an improved chance of hitting the target.

He rated the .300 Savage with a 180 grain RN bullet and the .35 Remington with a 200 grain RN bullet as "good." The best results with any rifle caliber used in O'Connor's testing were obtained with the .348 Winchester using a 200 grain Flat Point bullet. O'Connor summarized his results this way: "I found that the higher the bullet velocity, the sharper the point, the thinner the jacket, the lighter the weight, the greater the deflection."

My personal hunting experience has taught me not to shoot if the bullet is likely to hit anything on its way to the target. I think this is the best advice: Wait for a clear shot!