Tag Archives: Full Metal Jacket

Ballistics 101

What is “Ballistics?” “What is Muzzle velocity?” “What is ft/lbs energy?” “How does barrel length effect muzzle velocity”? “Do bullets travel in straight lines”? “What does {point blank} mean”?

Simply put, “Ballistics” is just a MEASURE of a bullet performance-when it leaves the gun (internal ballistics), while it is in flight (external ballistics), and when it impacts a target (terminal ballistics). Let’s take a look at these categories AND how to judge a bullet’s performance based on looking at its “ballistics”.

Internal Ballistics

Internal Ballistics is a numerical value that has to do with PROPULSION and ACCELERATION. You usually see Internal ballistics expressed in terms of “Muzzle Velocity” and “ft/lbs” of energy. The muzzle velocity is measured by a radar device that sits a few feet in front of the gun. GENERAL RULE of THUMB. The longer the barrel, the higher the muzzle velocity for a particular caliber. For example, the muzzle velocity of a 9mm being shot out of a 5 inch barrel will be HIGHER than the same bullet being shot out of a 3 inch barrel. This is occurs because of two basic reasons.  Firstly, the bullet is no longer assisted by the spiral grooves inside of the barrel once it exits the barrel. Once the bullet leaves the barrel it is relatively “independent” and is left at the mercy of the wind, GRAVITY, air friction, humidity etc. Secondly, the rapidly expanding gases inside the chamber also play a critical role in propulsion and acceleration. Once all of these high pressure gases are expelled, the bullet is left independent. Muzzle velocity IS THE FASTEST POINT at which the bullet will travel. The bullet will get slower as it flies down range (just like a football in flight).

Figure B1

Internal Ballistics Chart for common handgun calibers. NOTE. This ONLY gives you how the bullet behaves upon being propelled out of the gun. This is probably the most commonly referred to source of HANDGUN bullet power because handguns will be used at short ranges.

External Ballistics

External Ballistics is an observation of how a bullet behaves in flight. BULLETS DO NOT TRAVEL IN STRAIGHT LINES. (see figure B2 below) Bullets travel straight when leaving the gun, they rise, and then they begin to “drop”. GRAVITY IS A BULLET’S BIGGEST ENEMY. If you were to draw a line that represents a bullet’s flight path, it will look like a slight slope that gradually decreases downward as the distance increases (just like a football). The ultimate goal for a bullet is to maintain as much of its muzzle velocity as possible throughout its flight path. Every caliber has a different ability to fight gravity and air friction and stay airborne. Ballistics Coefficient (abbreviated “BC”) is a bullet’s ability to resist air friction and stay airborne. A high number means the bullet is more efficient at resisting air friction (negative acceleration). A high number also means that the bullet will retain MORE velocity as it moves down range.  Basically, BC is a measure of how Aerodynamic a bullet is. It is important to note that BC is merely a measure of a bullet’s ability to resist air friction. A high BC is NOT an indicator of how “good”  a round is.

Figure B2

Bullet trajectory of a .223 Remington (AR-15 bullet) out to 200 yards. NOTE. Bullet DOES NOT travel in a straight line.

Figure B3

.40 S&W (180 gr) on Left and .50BMG (750 gr) on right. Can you guess which round has a higher BC? If you guessed the one on the right you are correct. Just look at the shapes. Which one looks more aerodynamic? The .40 S&W has a BC of .164. The .50 BMG has a BC of 1.050. According to these numbers the .50 BMG is nearly 10 times as efficient as resiting air friction than the .40 S&W. Source http://www.hornady.com/store/50-BMG-750-gr-A-MAX-Match/

Bullet Drop

An important subset of External ballistics measures bullet trajectory-Bullet Drop. Simply put, “Bullet Drop” is a set of figures, either expressed in a line graph or a numerical chart, that illustrates the effect that gravity has on a particular bullet at various ranges. You may hear an experienced shooter compliment a round a say it shoots “flat”.  “Flat” simply means that the bullet has an efficient trajectory and resists gravity and air effectively.  Bullet drop charts are especially important for hunters, competitive shooters, and police/military snipers. For instance, a .300 Winchester Magnum may shoot “flat” out to 320 yards. This 320 yard distance is called “Point Blank Range”. Point blank range is the MAXIMUM “can’t miss distance” for a particular round. Beyond 320 yards, this round may start to “drop” (For instance the drop rate may be -6 inches at 600 yards). To compensate for this, an experienced shooter will have to aim HIGHER than the intended impact point in order for the bullet to hit on the desired location. Every bullet has its own unique drop rate. These unique drop rates are also influenced by humidity, wind, elevation, barrel length, bullet weight and bullet composition.

Fig B4

Bullet drop chart for common large game hunting cartridges. “300”, “600” etc indicate distance. -1.1, -7.5 etc indicate bullet drop rate at a particular distance. Question. What is the bullet drop rate for the 338 Lapua at 900 yards? The correct answer is -20.8 inches. This means in order to hit the desired target, the shooter needs to aim at least 20.8 inches HIGH. If the shooter doesn’t aim high enough, the round will simply bury itself in the dirt. (Just like a quarterback needing to LOB a football 60 yrds instead of throwing it straight).

Terminal Ballistics

Terminal ballistics is the study of how a bullet behaves when it impacts its target. Velocity, bullet type (soft point, hollow point, rifle, flat point, round nose), and target type all play important factors in terminal ballistics of a round. This is an EXTREMELY broad subject. For our purposes we will focus on basic characteristics of common rounds and how they behave. Panthera Armory believes in the utilization of visual observation as a learning tool. Ever heard of “ballistics gel tests”? These tests, even though they can be flawed, vividly illustrate how rounds behave when they hit soft tissue.

Video B1

This is how an Full Metal Jacket .45ACP behaves. The blunt shape of this round makes it go “through and through”.

Video B2

This is how the AR-15 bullet behaves. Notice how the round tumbles. This is called the “Yaw” effect. Other experts call it the “boomerang effect”. This is common among rifle rounds because of their high velocity. The yaw effect is responsible for causing massive trauma to surrounding tissues. This is how such a small rifle round such as the 5.56 can cause impressive terminal ballistics.

If you need further research on TERMINAL Ballistics Check out Brass Fetcher on youtube. By far the BEST slow motion close up Ballistic gelatin tests on youtube. You see the bullets deform and the gel oscillate from the kinetic energy transfer.

What is “caliber”? What is it a measure of?

“Whats a bigger caliber .40 or .380?” “Whats the difference between a 9mm and a .357?” “What does {caliber} mean?”

Caliber is basically the measure of the diameter of the projectile being fired. It is also a direct measurement of the diameter of the bore of a particular firearm. This measure can either be in fraction of an inch (i.e. .380) OR in millimeters (i.e. 9mm).

Common handgun calibers comparison

One common thing to remember in regards to caliber is that SOME calibers are not EXACT measurements. For instance, the .44 Remington magnum is NOT exactly .44 of an inch. It is closer to .429 of an inch than .44 of an inch. Another thing to remember about calibers is that we commonly see SAME caliber bullets stuffed in different size casings. For example, take a look at the figure above. If you did a little math, you will see that the .357 and the 9mm are the same diameter. The .40 S&W and the 10mm are also the same diameter. Let’s observe how this looks in a rifle example.

From left to right .308 Winchester, 30-06 Springfield, .300 Winchester Magnum (Missing is the Winchester 30-30, and the 300 Remington Ultra magnum)

These 5 cartridges are all in the “30 caliber family”. The projectile of ALL 5 of these cartridges measure’s .308 of an inch. These are essentially THE same SLUG stuffed in a different casing. “So which one is more powerful?” Take a wild guess between the 3 in the photo as to which one is more powerful. If you picked the one on the far right, you are correct. GENERAL RULE OF THUMB. Look at the size of the casing. The LARGER the casing, THE MORE gunpowder its going to hold. The MORE GUN POWDER the casing holds the faster the bullet is going to travel. The faster that bullet travels the more kinetic energy its going to have etc..

GRAIN-The STANDARD unit of Bullet weight measurement

You may hear or read of different bullets being 200 grains (often abbreviated “gr”), or 180 gr. This is the WEIGHT of the bullet/slug/projectile. For example, The .40 S&W is available in 135 gr, 155gr, 165 gr and 180 gr. Lets ask ourselves a few common sense questions and establish a few GENERAL ground rules (there are a few exceptions with high performance ammo manufacturers) 1. The LIGHTER the projectile, the higher the velocity (bullet will move faster through the air) but will not penetrate as deeply as a heavier projectile. 2. The HEAVIER the projectile the slower it will travel, but will work wonders when it comes to penetrating surfaces and retaining momentum. SOO..if you had a .40 S&W pistol with FMJ’s and you wanted to PUNCH THROUGH A WINDSHIELD (or sheet rock, or sheet metal, or plywood) and knock out a target in the front seat, which weight would you use? 135 gr or 180 gr? The 180 gr choice would be more practical. The slower moving 180 gr will retain MUCH more of its kinetic energy than the much FASTER moving 165 gr.

“Sooo…since a 230 gr .45ACP is a bigger bullet than the .357 Magnum which weighs 158 gr, is it more powerful?” The Answer is NO. Take a look at the figure below. 

.357 S&W Magnum (158 gr) on left .380 ACP (95 gr) in middle and .45 ACP (230gr) on right.

Obviously the .45ACP bullet diameter is wider than the .357 magnum. The .45 ACP also weighs more. SO…which one generates more power? To answer this question, Remember the GENERAL rule of thumb we previously discussed. That .357 magnum has a LOT more powder in its casing. This allows the .357’s 158 gr projectile to travel a LOT faster than the 230 gr .45 ACP. This considerable advantage in velocity allows the .357 to generate over TWICE the energy of the LARGER .45 ACP. GENERAL RULE OF THUMB…A LARGER DIAMETER CALIBER IS [NOT] ALWAYS MORE POWERFUL.

 

What is an “Extraction”? What is Threat Assessment?….How Important are they?

“I’m right handed…and I carry on my right hip at 5 o’clock..do I need to learn how to extract my weapon with my left hand?” “Should I learn to draw my weapon with the opposite hand?” “If I’m in a tight situation will I be able to extract or draw my weapon with ONE hand”? These are questions that every RESPONSIBLE Conceal Carry Holder SHOULD BE ASKING themselves. To start off… Let’s look at a scenario I experienced a few months back…

Its 10am, mid December about 40 degrees. I’m walking to the bus stop. I hear a large dog bark aggressively, but I couldn’t determine WHERE the dog was barking. SO, I stop and made an about face to figure out the dog’s LOCATION. I see a medium sized healthy American Pit Bull Terrier sprinting down the stairs and eventually made his way on to the ground. Distance was about 50 yards. Dog was running towards me, mouth wide open, ears slicked back. I hear the owner screaming at the dog…”Molly!!!…you better not bite him!!!..Molly!! Leave him alone!!!” Molly gets about 5 yards from me and I hold my ground and look her in the eye and she retreats. Luckily for Molly I’m a dog lover…or else she would’ve ended up being vulture meat. Let’s take a look at some variables in this scene…because I learned a LOT.

Threat Assessment

Know when its time to run. Of course you can’t outrun a pit bull terrier. I was thinking….”If this dog bites me on my right forearm..will I be able to extract my gun with my opposite hand and put the dog down?” “Should I extract my weapon and discharge a warning shot to scare the dog”?  “What If I draw my weapon and shoot and miss the dog?” “Surely this 180gr  .40 S&W FMJ at 5 yrds would go through the dog like paper and tear up somebody’s car…or worse”. “Let me hold my ground and see what Molly does because she hears her owner’s voice yelling at her.” All of these were calculations I had to make in less than 4 seconds. Luckily, Molly was a dog that just wanted to play. I actually made the right call in this instant. I made eye contact with the owner afterwards and told her “MOLLY NEEDS A LEASH!!” This incident with Molly also made me consider another discipline in the realm of RESPONSIBLE CONCEAL CARRYING. The EXTRACTION.

The Opposite Hand Extraction

Later that night, I practice on extracting my weapon at home with the opposite hand. I was thinking “What IF Molly had been an aggressive dog and she latched on to my shooting hand and disabled it?” If Molly had been a REAL attack dog…I would been on the ground instantly and she would’ve been on my neck. See how quickly things happen? Police, Troopers, Soldiers, and anybody with ANY type of Paramilitary training practice and train on this. “What if my shooting hand is disabled?…Can I draw my weapon and fire a few point blank shots with the opposite hand?” ASK YOURSELF THESE QUESTIONS AND ADDRESS THE PROBLEM. IT COULD SAVE YOUR LIFE. PRACTICE THE OPPOSITE HAND EXTRACTION WITH AN EMPTY CHAMBER.

Issue with this extraction?…We didn’t see him draw with the other hand. What if the OTHER arm was shot and disabled??

 

What type of ammo should I use in my conceal carry firearm?

“What are the pros and cons of hollow points?” “What are the pros and cons of FMJ’s (full metal jackets)?” “Are hollow points barbaric?” “Do hollow points make me look blood thirsty?” “What about Xtreme Penetrators”? These are questions that are asked by the common first time gun owner. Lets say you just purchased your gun, it fits well, its concealable, and you are fairly decent with shot placement. The gun store clerk shoves a box of “Hornady Critical Defense” ammo towards you and fiercely recommends it for personal defense. Could you visualize or articulate the difference between Hornady Critical Defense rounds and regular ol’ bullets (FMJ’s)?

Full Metal Jackets (FMJ’s)

A full metal jacket is usually consists of a SOFT metal core that is encased in a harder metal such as brass. FMJ’s are usually referred to as “ball” ammunition in the military. Full Metal Jackets do a decent job at damaging or penetrating HARD surfaces such as windshields, sheet rock, sheet metal, tin, stone, wood and ceramics.  They also devastate soft targets such as flesh and ballistics gelatin.

FMJ Drawbacks

One main drawback of FMJ’s is that they have a tendency to overpenetrate-they don’t stop until they’ve expended ALL of their kinetic energy. By the time FMJ’s have expended all of their kinetic energy they may have passed through an attacker’s body.

Common Calibers in Full metal jackets

If you are shooting an assailant with FMJ’s from a high velocity CONCUSSIVE caliber like a .357 SIG, .357 Magnum, .40 S&W, or a 10mm, you may be increasing the chances of overpenetration. This phenomenon occurs when the projectile FAILS to stop traveling because it has not expended all of its kinetic energy inside the target (this is also called a “through and through”, or an “exit wound”). These overpenetrators are free to fly around and tear up someones engine block on their car, punch through somebody’s vinyl siding, kill somebody’s dog, or even ricochet and kill an innocent bystander.

Jacketed Hollow Points (JHP’s)

A hollow point is basically a bullet that has been hollowed out. This hollowing out causes the bullet to expand when it hits a soft target such as ballistics gel, flesh, or water. This design allows hollow points to expend nearly ALL of their kinetic energy INSIDE of the soft target. Expansion causes the surface area of the bullet to increase substantially. This virtually eliminates the possibility of over penetration. Just visualize FMJ’s as spears. Spears pierce and cut straight through a target. Now imagine Hollow points being like sledge hammers. Sledge hammers crush,Smash, rip, and tear through things. The spear and the sledge hammer are both incredibly lethal, but they work in different ways.

 

Hollow points are ILLEGAL to be used by armies around the world according to the Hague Convention. But they are the ammunition of choice for Law Enforcement in America (hmmm).

Hollow Point Drawbacks

One performance drawback of the Hollow point design is the fact that it relies on liquid or semi liquid targets (like flesh, water, or ballistics gelatin) for expansion. If it strikes a hard surface such as a windshield, it may not punch through. Another performance drawback is that the hollow point expansion can be defeated if an attacker has on THICK clothing like a sweat shirt.Thick clothing will cause premature expansion and basically cause the hollow point to behave like a weak FMJ. “Hornady Critical Defense” solves this problem by filling the hollow point cavity with a rubber like polymer. This eraser-like material DELAYS expansion when/if the bullet strikes heavy clothing and allows the hollow point to behave like a hollow point should.

Count up the cost and weigh your options. Look at the pros and cons of both ammo types. Some gun owners alternate FMJ’s with JHP’s in the magazines to get the benefits of both. DO what works for you.