RN bullets for heavy woods? Brush buster myth.

[Bigfoot]

I've put off asking this question because it seems like an old hunter wives tale and I didn't want to look stupid(too late now), but I've just about run out of gun related stuff to read about. (oh no ) I'd been planing to retire the 30-06 BAR and diversify, get a .260 barrel for my Savage for deer and a 338WM for elk, but I keep reading suggestions that light fast bullets from a .260, 243, 25-06 etc. deflect more than a slower heavy RN. I thought this "brush buster" theory was long dead, I know that all bullets deflect, but to what degree?

Besides the great expansion properties, does anybody load RN bullets for less deflection? Should I hang on to that BAR and load it down a bit with RN 180s for heavy cover deer hunting? It's about a pound heavier than the Savage.

 

[beerslurpy]

Heavy bullets for brush.

Kinetic energy is 1/2*m*v^2.

Hitting brush reduces velocity in proportion to the amount of brush passed through. Since mass stays the same no matter how much brush you go through, the more mass the bullet has, the more kinetic energy it will retain going through obstacles.

Also, heavier projectiles will be less amenable to being deflected by brush.

The downside is that heavier projectiles will have less velocity and thus wind drift more and drop more for a given distance traveled. They will tend to have a higher ballistic coefficient (same frontal area with more mass behind it) and thus not bleed off velocity as fast. This translates into better long range performance.

 

[ghost squire]

Ummm yeah.

I forgot exactly what my ballistics book says but I can get back to you tomorrow on it.

Spinrate, bullet length and weight all play significant roles in brush busting capability.

 

[JohnKSa]

Actually the deflection is MOST dependent on:

1. The type of strike to the deflector (glancing strike/square strike)
2. The distance from the deflector to the target.
3. The sturdiness of the deflector.

The most important factor is the type of strike. If the bullet hits a branch squarely it will either blow up or go right through in a more or less straight path. If it glances, it will be deflected significantly.

The farther the deflector is from the target, the more effect a deflection will have. If the deflector is very close to the target, even a severe deflection may still hit the target. But if the deflector is a good way from the target, even a tiny deflection will be enough to cause a miss.

Someone did a test for a magazine article some years back. The conclusion was that the factors above were MUCH more significant than ANY aspect of caliber, bullet weight or velocity in determining the amount of bullet deflection.

Here's a quote from Safari Rifles by Craig Boddington. (Which I highly recommend, BTW)

We picked out a decent (cape buffalo) bull, nothing monstrous, and when he turned broadside I fired a very careful shot from my .470. The herd ran, of course, but there was no sound of the bullet hitting, no reaction, and, on inspection, no blood. I asked Paddy (the P.H.) what happened and he shrugged. "I dunno. I saw a leaf fall."

We walked the ground, and there was a pencil-like vine neatly severed by a bullet just a third of the way toward the buffalo from where I'd fired. It doesn't take much.

Next time you consider about shooting through brush at an animal, ask yourself if what you're carrying has more punch than a .470 double rifle shooting 500 grain bullets. Because those monster projectiles can be sufficiently deflected by a "pencil-like vine" to completely miss a cape buffalo. Boddington provides another similar anecdote in the book.

The bottom line is that if you aren't SURE you have a clear bullet path to the target, you shouldn't shoot. Taking a shot when you KNOW you are going to hit brush is irresponsible, regardless of the caliber.

 

[beerslurpy]

Lenth is proportional to mass within a caliber, so this isnt really a different factor.

Spinrate is only important because a bigger projectile moves at a far slower velocity, more so if it takes up case capacity otherwise used for powder. You need a faster twist for slow projectiles or they wont stabilize properly.

This is why the soviet attempt to make subsonic 7.62x39 failed- the barrel had too slow a rate of twist for the slow bullets. They would come out of the barrel tumbling and hit the baffles. A less extreme version of this will affect a brush-buster round in that it will end up being sideways somewhere downrange and bleed off a ton of velocity really quickly once this happens.

 

[Bigfoot]

I forgot exactly what my ballistics book says but I can get back to you tomorrow on it.

Spinrate, bullet length and weight all play significant roles in brush busting capability.

Thanks Ghost Squire I'd appeciate the elevation that facts would bring to this thread. I'd assume that nose shape and bullet velocity would factor in as well, but I could be wrong.

Guys, I'm no newb so please skip the ballistic basics and the lectures on hunting responsibility. You can't always see a branch when looking through a scope. We spend hours deciding on the correct cartridge/gun/bullet for the game and conditions that we intend to hunt. This is just another variable that I'm considering precisely because I don't want to wound and lose my deer.

Thank you.

 

[cracked butt]

You need a faster twist for slow projectiles or they wont stabilize properly.

not quite, but you are on the right track.

A longer projectile needs a faster twist rate to stabilize it. A faster projectile requires less twist to stabilize it, mainly because extra velocity increases the bullet's RPMs.

Search 'greenhill formula'

Here's a simplified explaination of it: http://www.loadammo.com/Topics/July01.htm


At any rate, 'brush busting' calibers are a myth.

 

[Don't Tread On Me]

Heh, I'm waiting for someone to come along and claim that a flower petal will instantly deflect a .223 45degrees.


Folks, I don't know what kind of brush you're trying to shoot through, but any centerfire rifle cartridge is moving at serious velocity with serious momentum. Not saying deflection doesn't happen, or that there aren't better options out there - but how many consecutive twigs does it take to send a 168gr .308 off course enough to miss a kill on a deer? If you're shooting through that much brush, perhaps you should try and find a clearer shot. Shooting through light stuff isn't going to stop or deflect a shot like that to cause you to lose the game or the kill. For the brush to be thick enough to cause the shot to totally miss, or to lose enough energy, it would probably have to be thick enough to where you couldn't see through it in the first place - and if you're responsible, you don't shoot at things you cannot see.

 

[JohnKSa]

The answer is that the deflection is FAR more heavily dependent on the deflector than it is on any parameter relating to the firearm or bullet.

I just gave you a real world scenario published by a respected authority on firearms where a VERY large and heavy RN bullet was deflected by a thin vine such that it didn't even hit the cape buffalo it was aimed at. All the calibers you mentioned fire bullets that weigh a fraction of the bullet in the scenario.

In a given scenario, a heavy, RN bullet will deflect a bit less than a light spitzer, but that improvement is tiny compared to the contribution of the other factors in the situation.

The real factors that determine whether a bullet will hit or miss after being deflected are the properties of the deflector. The contribution of the bullet design is not significant when compared to these effects. The experiment showed that even relatively large bullets could be deflected enough by hitting a tiny obstacle to turn a good shot into a miss or, worse, a gut shot.

The bottom line is that if your bullet strikes something before it hits your target, then your preparation, your equipment choices, your skill, your practice are all rendered useless. What happens from that point on is essentially random chance.

You asked if it was a myth. Experience and experimentation both say that it is.

This is just another variable that I'm considering precisely because I don't want to wound and lose my deer.

And the facts say that all the precise consideration in the world won't help significantly because the variable you're considering is not a significant contributor. The only thing that will help is your bullet not hitting something on the way to the target.

but how many consecutive twigs does it take to send a 168gr .308 off course enough to miss a kill on a deer?

Read the quote from Boddington's experience. ONE "pencil-thin vine" was enough to send a 500 grain .470 bullet off course enough to not just "miss the kill" but COMPLETELY miss a cape buffalo.

 

[Lucky]

AR15 some guy experimented with a test-rig with wood dowels. IIRC 55 grn 5.56 really did deflect if it hit a thin dowel. I think he was testing a Vietnam-era myth.

 

[cracked butt]

I would think a small twig would be worse than a large branch or small tree trunk. With a small branch, there's less of a chance of the bullet hitting it square and staying on a relatively straight course. A bigger piece of wood might offer a chance of little deflection if hit near the center.

 

[Cosmoline]

The advantage of the RN bullet comes only when it hits the game. There it supposedly has better bone-breaking potential and with more primitve SP's a greater chance of expanding. I don't believe there's any such problem with more advanced bullet designs, and properly made spitzer HP's will now expand quite well. But 100 or even 50 years ago this was not the case.

 

[45crittergitter]

but how many consecutive twigs does it take to send a 168gr .308 off course enough to miss a kill on a deer?

Exactly one (1) small twig, about 1/8" in diameter, can and did cause a MOA 30 caliber 180 grain Partition moving about 3100 fps to deflect enough to completely miss a standing broadside whitetail at around 30 yards.

Practically speaking, no common small arms cartridge or projectile is significantly resistant to terrible deflections from very small interfering objects. You may see some improvement with very large calibers, i.e., shotgun slugs and 50+ caliber rifles.

 

[jerkface11]

I read an article once where they tested different cartridges for shooting thru bursh. The ONLY 2 that didn't deflect enough to miss a deer were .22 hornet and .416 rigby. At that point the author gave up.

 

[gezzer]

I read an article once where they tested different cartridges for shooting thru bursh. The ONLY 2 that didn't deflect enough to miss a deer were .22 hornet and .416 rigby. At that point the author gave up.

Yep all bullets deflect. the more distance between the target and the deflector more chances of deflection. The easy way is don't shoot though brush ,wait for a clear shot.

 

[Lucky]

Could we theorize that flat-nosed bullets would be less likely to deflect than round or spitzers?

 

[cracked butt]

Could we theorize that flat-nosed bullets would be less likely to deflect than round or spitzers?

You could, but until its tested, it doesn't mean much.


My take on how the 'brushbusting caliber' myth started:

At some point in time, Winchester or some other maker started offering a carbine version of one of their lever actions. Hunters who bought them found that they are easier to carry in the thick stuff than the full length rifle version of the lever action or a bolt action. Things like "this is a handy rifle in brush" were said and would have been and still are true. Like the old game where where you wisper a message into someone's ear and they whisper it to the next person and so on down the line, people hearing that these are excellent brush rifles started saying " the 30-30 rifle is a great brush rifle" and eventually it mutated to "The 30-30 is a brush round" and finally "the 30-30 is a brush busting round" Then people started to surmise that bullets with poor wind bucking properties must be really good at plowing through brush, never mind the fact that that they have to be designed that way to work in a tubular magazine. Now, thanks to the miracle of the internet, we have gun people around the world telling others about "brush busting" calibers.




The whole myth is the same leap of logic as the old wives' tale where going outside in the winter without a hat on will give you a cold.

 

[RON in PA]

Brush busting bullets are an old myth. Many years ago the American Rifleman had an article on this subject. They shot various caliber bullets through dowels. All were deflected to some degree, but the brush busters (slower round noise bullets of larger caliber) seemed to deflect more than small caliber spitzer bullets. Moral of story, don't shoot at a deer unless you have a clean shot.

 

[R.W.Dale]

I laugh every time I read something on this subject. Bacically there no one cartrige that shoots through brush. What people do (gunwtiters included) is confuse brush busting calibers with something that does exist the brush gun

A brush gun is an easy to carry short firearm , That is preferably cheap or already beat and scrached up. You want an action type that will allow for a fast follow up shot pumps, semiautomatics and leverguns are ideal.

Now here is where the caliber choice comes in. You want to choose a caliber with managable recoil as to not negate the ability to make that follow up shot, BUT the caliber needs to be powerfull enough to kill an animal cleanly even if the deer never presents an ideal broadside shot (lots of quartering away shots) Preferably a big bullet that stands a good chance of anchoring your game. In some of the places I hunt tracking an animal 75 yds midas well be 3 miles

Bacically nothing will reliably shoot through brush. I once shot a buck once at a range of 30' with a full load of number 4 buck, the load of buckshot hit a very small 1/8 sapling halfway between me and him. This produced a wound pattern in the deer that had a large group of pellets at the very front of the chest cavity then about 18" of undamaged deer then more pellets in the guts.
And that was a load of buckshot what do you think it would have tone to a single bullet