T-65: Original designation for the U.S. Army's 7.62 x 51mm NATO cartridge. The T-65 was developed by Winchester in the early 1950's and was introduced commercially as the venerable caliber .308 Winchester rifle cartridge. Also know as .308 Win.
TACTICAL: Relating to or using tactics, which could include established principles and procedures for combat effective fire and maneuver. Of, relating to, used in, or involving military or naval operations that are smaller, closer to base, and of less long-term significance than strategic operations. Carried out in support of military or naval operations: tactical bombing. Characterized by adroitness, ingenuity, or skill.
TAKE DOWN: A gun which can be easily taken apart into sections for carrying or shipping.
TAKE DOWN PINS: Removable or sliding pins that are slide or removed from a gun so it can be taken apart. The most common "take down pin" gun is America's rifle the AR-15 and the American military version the M16.
TANG: An extension of the receiver into the stock.
TANK: Military Armored vehicle that has caterpillar traction and is armed with machine guns, cannon, rockets, or flamethrowers. It was developed by the British and first used (Sept. 1916) in World War I. In World War II tanks and tank tactics were greatly improved. The German army, using large numbers of tanks, overran Poland in less than a month. In mass tank battles on the plains of Europe and North Africa the tide often swung toward the side with the best tanks. Since World War II the basic features of tanks and tank tactics have remained unchanged, although there have been numerous technological refinements. Tanks are vulnerable to recoilless weapons and various antitank missiles, but they remain indispensable, because of their mobility and versatile weaponry, wherever the terrain is suitable to their operation.
TARGET: A mark or object to shoot at. Something fired at with a gun. Many types of targets exist for shooting competition and recreation. Target types include Paper with a traditional "bulls eye" or concentric rings and circles, human torso type silhouette targets are typically used by law enforcement, metal plates of varying sizes and shapes to include game animal forms and clay or frangible items used for skeet or trap shooting. Targets can be made of just about anything, the most common being paper and cardboard.
TARGET, CLAY: A circular, domed frangible disc used as an aerial target for shotgun shooting games. Originally formed out of clay, modern targets are a combination of pitch and limestone. Dimensions and weights are regulated by trap and skeet shooting associations. They are often called "clay pigeons."
TARGET RIFLE: Rifle used for specified types of target shooting. Target rifles fall into three general groups: offhand or Schuetzen; Creedmoor or long range; and bench rest. These three group classifications originated in the last century but are still descriptive today, the principle being that the offhand rifle is today called the Free or International Rifle. We generally call the Long Range Rifle, long range rifle. Since several years ago, the latter type was also referred to as the Wimbledon rifle. Bench rest target rifles are still called by that name.
TEFLON: Trade name for a synthetic sometimes used to coat hard bullets to protect the rifling. Other synthetics, nylon for instance, have also been used as bullet coatings. None of these soft coatings has any effect on lethality.
TELESCOPIC SIGHT: A small arms sight that employs optics to provide a magnified view of the target. A telescopic sight does not make a small arm more accurate, but rather helps the shooter to distinguish a distant target from its background. Also refereed to as a Scope.
TERMINAL BALLISTICS: The branch of ballistic science which deals with the effects of projectiles at or on the target. Terminal ballistic measurements include impact energy, penetration depth, weight retention, wound channel and bullet expansion. Terminal Ballistics is concerned with the phenomena occurring at the termination of the projectile's flight; such termination may result from impact on a solid target or the explosion of the projectile.
For detailed information on Terminal Ballistics see the article below.
Terminal ballistics is the science of what happens when the bullet strikes the target (and thus the mechanism of incapacitation). For a very long time this field was based on myths, misunderstandings, and in many cases outright misstatements. It wasn't until accurate tissue simulates and modern high speed x-ray photography started to be utilized that much of what happens began to be understood more fully.
Even today there is still
a lot of terminal "bull-istics" being put forth by self-styled experts
based on so-called "street data," pet theories of the proponent, and
some cases even manufacturer's incentives. However, those who have taken
the time to research the subject and who understand the medical
principles involved have learned to separate the bull from the bullets.
- A bullet constructed of hardened material or carrying a hardened core
specifically designed to penetrate bullet resistant, or armor-plated
targets such as tanks, trucks, and other vehicles. Depending on the
definition used for "armored" any small arms ammunition could be
considered armor piercing. As an example, a target designed to resist
pistol ammunition can be penetrated by rifle ammunition, or a target
designed to resist rifle fire ammunition can be penetrated by a light
The subject of
incapacitation is one of vital interest to anyone who depends upon a
firearm to either protect their life from an assailant or who needs to
stop a dangerous animal. What is needed in both cases (and even in the
case of a non-dangerous game animal) is to turn off--S T O P--whatever
the target is attempting to do, whether it is trying to kill you,
someone else, or simply trying to run away. Whether or not the target
eventually dies of the wound(s) is of only academic interest at the
moment of the shot is fired. You want (need) instant (or as near to
instant as you can get) results!
This particular profile is that of an early .45ACP 185gr. Silvertip Winchester @ 940 f/s. This is a classic non-fragmenting expanding bullet wound profile. The narrow portion at the start of the permanent cavity is called the "neck" and its length is a function of the bullet's design. This particular load is a little short on penetration at 25cm (9.8") with an expansion of .85". As a comparison the Hornady +P 230gr XTP at 880 f/s gave 15.6" penetration and .72" expansion, the Hornady 200gr XTP at 850 f/s gave 18.5" and .54", the Winchester 230gr Black Talon at 858 f/s gave 13.5" and .73", and the Remington 185gr at 1020 f/s gave 10.5" and .83". Interestingly, Winchester must have got the word because a later lot of this ammunition gave 882 f/s and 11" of penetration and .74" expansion. For comparison the GI M1911 Ball ammo (230gr at 869 f/s) produced a penetration of 26".
This is the wound profile of the 7.62x39 PS Steel Core AK-47 round at 2340 f/s. Great penetration but otherwise not very impressive, eh? The permanent cavity is flat in cross-section. I removed two sections so the image would fit on the page better. At around 60cm the bullet yawed downward and wound up base first as shown.
This profile is of the Winchester .30-30 170gr Silvertip at 2020 f/s. This is typical of medium velocity, expanding rifle bullets.
This profile is of the Winchester .30-06 150gr Softpoint at 2923 f/s. Note the larger permanent cavity than the .30-30 but almost identical penetration. Not something you want to get shot with.
What to do, what to do...
While the energy dump school
has been disproved there is still a minor battle going on between the
temporary cavity and big hole schools, and perhaps the real answer lie
somewhere between the two. There are many failures of both the high
performance/high velocity temporary cavity loads (especially the lighter
bullet weight loadings) and also the big bore/big hole loads. While
general experience seems to favor the big hole loads, nothing is
certain. A lot still depends on the condition of the target.
I hope that the forgoing has provided some food for thought and I'm sure that I will be hearing from some of you. You can email your comments and ideas to me at [email protected].
Ah ha! Now we come to a controversial topic. It probably should really be under the heading of "Terminal Ballistics," but for now we'll discuss it separately. The topic is "power" and just what "power" increments are meaningful. As with the pistol, the way that a rifle bullet works is by creating as much permanent damage as is possible and what does this is the destruction of tissue by the bullet's passage.
The trick is to determine the damage level you need for your intended target and to then choose your weapon. It stands to reason the bigger and/or more dangerous your target the more damage you need/want to do. As a bonus, with rifles we don't have to worry much about a "power ceiling" as we do with pistols because controllability is not a real issue here.
Unfortunately, there has never
been the level of study put into the effectiveness of rifle ammunition
that has gone into pistol ammunition so a lot of myths still exist for the
rifle shooter. Let's see what we can discover together.
If one is to believe the ammunition manufacturers and the so-called gun rag "experts" all one needs to do is to drive a given bullet faster and faster to get more "power." If one looks at the kinetic energy figures one simply needs to drive one's bullet to the next increment up in KE and you are ready for bigger/more dangerous game. According to them, "out there where the game is big, instead of your puny little .308 what YOU need is the new.300 Remingchester Soooper Magnum" and you are all set. To paraphrase the ancient masters, "Hog wash!" It is true that at the higher impact velocities of rifle ammunition (2300-2700+ fps), that the vaunted hydrostatic effect comes into play, but not at the level one would expect from reading the magazine hype.
One big disadvantage in increasing bullet velocity is that bullets are designed to expand properly over a fairly narrow range of velocities. If driven too fast they "explode" on impact giving a shallow wound channel or if not fast enough they fail to expand and just punch a small hole. A superficial wound will most likely, as it will with a human antagonist hit with a weak pistol shot, simply make what you shot more aggressive or allow it to escape.
Even the ammunition manufacturers admit under close questioning and a couple of sips of their favorite spirits that the KE figures in their ballistics tables are there to impress the uninitiated and sell ammo (just like the pistol data.) . And impress them it can because KE is a factor of the square of the velocity, and as we all know, velocity sells now days--in spite of what we presented on the external ballistics link. Look at the table below. If we are to believe it, all we have to do is buy the latest big powder bottle and we are in business
Let's see now. A 150gr .30 caliber bullet at 2700 ± is generally considered suitable for game up to about 800 pounds by most authorities. The same bullet at 3500 out of the 300 Weatherby develops over 4000 ft lbs (which is fairly close to that of the .458 Winchester with a 500gr bullet which at 2000 fps which produces about 4440 ft lbs.) Which do you want to have in your hands when that Cape Buffalo gets an attitude? To get even more absurd, theoretically one could drive a 55gr .22 caliber bullet to slightly over 5100 fps and develop 3200 ft lbs of energy which some would have you believe makes it the equivalent of the .35 Wheelan with a 250gr bullet at 2400. Assuming you were sober which one would you want to use against an irate lion at 25 yards? Obviously kinetic energy isn't what we are looking for to quantify "more powerful."
It must be noted that kinetic energy does come into play with high velocity hard "penetrator" projectiles such as the "dart" rounds used in tank canon. There, the kinetic energy is used to literally burn through the target. I'll leave it to you to work out the KE of the M829 APFSDS-T (Armor Piercing Fin Stabilized Discarding Sabot-Tracer) 120mm round. It throws a 9.41 pound (that's 65,870 grains), 1.06" diameter, 31" long, depleted uranium dart at 5480 fps from the 120mm M256 smooth-bore tank canon on the M1A1 and M1A2 tanks. You can think of it as a really big bore Remington "Accelerator" round. For those of you who left your calculators back at the office, see the foot note at the very bottom of this page for the answer, along with a picture of a "dart."
However, KE might, however, be able to serve as an index of effectiveness at different ranges when comparing the same bullet weight and diameter at different velocities.
We have seen on the external ballistics page that velocity doesn't have a tremendous effect on trajectory until the DV exceeds 200 fps and even then the effect is really only noticeable at extreme range. It appears that the main effect of a velocity increase is to lengthen the range at which a given level of performance occurs. Just for grins lets assume that the given level of performance is the delivery of 1300 ft lbs of energy. (Yes, yes, I know... let's just assume and we'll also assume that we have a magic bullet that performs properly over a wide velocity range.)
I case you are wondering, I came up with this figure from Jeff Cooper's description of what the .308 Scout rifle was supposed to do--the taking of a target of up to 400kg (880 pounds), and his belief that 300 yards is the maximum range that one should attempt shots at game animals. (I have to agree with him because the average shooter can barely identify a target at 300 yards let alone hit it from field positions and in my experience an awful lot of folks can't consistently hit targets at 100.)
If we take 300 yards as the maximum "reasonable" range and assume the 150gr bullet as "standard" we come up with about 1300 ft lbs at 300 yards out of a 19" Scout so we'll use that as a standard of comparison. We'll launch a 150gr Hornady flat base from a.308 Scout, a .30-06, and a .300 Win Mag and look at the energy figures.
MV = Muzzle Velocity in FPS - Feet Per Second
It would appear, if our assumption is correct, that all increasing MV by 300 fps does is to extend the "equivalent effective range" by about 100 yards. Since 300 yards is about the most anyone should attempt a shot at the whole thing kind of pales into insignificance. So the 300 Win Mag will do the same thing at 500 yards that the .308 will do at 300--Big deal! The target has to be hit first and I can count on the fingers of one hand the folks I know who can consistently hit with their first shot at 500 yards let alone those who know where their rifle shoots at that range. Besides you are burning 20-30 grains more powder just to get some meaningless increase.
Too many duffers believe the hype about the "magnums" and think that "more cartridge" will compensate for lack of marksmanship. In addition, all that powder going off causes faster erosion of the barrel's throat--not that many armchair hunters practice a lot with their rifles--and the increase in muzzle blast causes their already poor marksmanship to grow even worse. For the rare hunter or long range specialist who can make use of the slightly improved long range trajectory and power available from the big powder bottle rounds they may be of use. But for the "masses" I don't think so.
Ok, so we now know that upping velocity basically just extends the range at which a given level of performance occurs. The rest of the world needs something else to get more power.
If caliber remains the same, an increase in bullet weight increases what is know as sectional density which is basically the ratio of weight to impact area. (It also produces lower velocities in the same cartridge.) The main effect of bullet weight is to increase penetration (all else being equal) although there can be a slight increase in the expanded bullet's diameter (assuming it expands) since there is more material to work with. This can make it a more effective bullet assuming bullet construction is up to the task.
While penetration is to be greatly desired it is not the only thing we want. If all we want is deep penetration we can just use fully jacketed or bullets with a hardened steel penetrator core and we'll be able to punch clear through most things. However, once again I don't think you would be too happy about facing an irate moose or a cape buffalo with an attitude, up close and personal with a .308 loaded with M62 AP ammo. However on larger thin skinned game (within reason) going to a heavier bullet in a given cartridge will give you some more penetration.
Below is a table of the sectional density for some common bullets weights and calibers. Note that as the caliber is increased the "standard" bullets become proportionally heavier.
Note the high sectional density for the 160 grain caliber .264 bullet. This is one reason why the 6.5 x 54 mm Mannlicher and the 6.5 x 55 Swedish cartridge was so effective on big game. It drove deep and expanded well. The other effect of increasing bullet weight is to help increase the ballistic coefficient of the bullet. It the bullet shape stays constant increasing the weight can yield a slight trajectory effect at long ranges. We'll use the Hornady .30 caliber flat base bullets bullets as an example. (Data from Hornady.)
However, remember that we have shown on the external ballistics page that a 15% change in BC at the same velocity has a negligible effect at reasonable ranges. We also saw on the external ballistics page a negligible change in useable trajectory with different bullet weights in the same cartridge if zeroed at the same range. It therefore appears that going to a heavier bullet in a given cartridge merely gives you some extra penetration (assuming proper and consistent bullet expansion).
Lets look at what we could do by using a bigger cartridge case with the same bullet diameter and burn more powder to launch a heavier bullet. All data based upon a 225 yd zero range with a 1.5" LOS. C1 ballistic coefficients are respectively .358, .431, and .485.
Here we might be able to make an excuse for a bigger case in the same caliber. Raising the bullet weight and keeping velocity about the same or greater allows us to drive more mass deeper and in those cases of large thin-skinned game may give us the additional penetration and "umpf!" we are looking for when going after BIG thin skinned game. In addition, note that with the same zero range the trajectories are all very close until one gets out past 300 yards. Unfortunately, you will still generate a small wound channel and while it might suffice for docile targets we need to be able to cause a more certain reaction on targets that might decide to cop an attitude and attempt to ruin our big day in the field.
If you want a bigger hole, start with a bigger hole maker. As with the pistol, increasing the bullet diameter serves to increase the diameter of the permanent wound channel, which in and of itself is a "good thing," and it also, as a matter of course, increases bullet weight which helps to insure penetration.
Since it is apparent from previous investigations that for the most part simply jacking up the velocity does not make a particular cartridge more suitable for larger or more dangerous game, we may want to keep in mind that if we really need more power we really need to increase the bullet weight and also the bullet's diameter. This gives us more mass which is constant and a bigger permanent hole rather than velocity which is not constant. If you noticed in the sectional density table the "standard" bullets get proportionally heavier and heavier and for the most part have greater sectional density as caliber increases.
Notes from the field indicate that just as with the pistol, a bigger bullet has a greater effect on its target in the vast majority of cases. Deer usually fall faster when hit with a .35 than a .30, etc. given the same hit.
At this point I am sure that someone is asking, "How great an increase in caliber is needed to make a statistical difference?" That's a good question and as of yet I have not discovered an authoritative answer. I tend to think that a 25% to 50% increase in impact area is needed to be noticeably more effective but that theory is open for rebuttal. However, if one accepts that that .40 pistols are supposed to be noticeably more effective than the 9mms, one can look at the table below and see that a .40 cal has about 25% more area than a 9mm (.358). Same thing with the .30 caliber rifles and the .35 caliber rifles so perhaps there is something to this idea. One African hunter stated, when asked why he used a .600 Nitro double rifle, "Because they don't make a 700!" Nothing like a bigger hole!
An interesting inference can be drawn from the hunting regulations in African countries visited by hunters. They base their regulations not just on KE but also on bullet diameter. The following are taken from the regulations in place in Rhodesia. (Oops! I mean The People's Democratic Republic of Zimbabwe.)
Part A - Thick skinned,
dangerous game [Buff, elephant, hippo] requires a 9.3mm bullet (.362") or
greater diameter bullet with not less than 5.3 kilojoules (3,909 ft-lbs)
muzzle energy; [Yes, I've noticed. Only a fool hunts buff with a
".375." Maybe they are trying to kill off the Yankee tourists but at least
they realize you need some kind of a "real" gun for the bad boys!]
One thing not touched upon in this discussion has been the effect of bullet construction. While this topic could take up several pages for discussion I think that it is safe to simply keep in mind that more weight or greater diameter will be useless if the bullet is not up to the intended task. A bullet that is too soft will open up too quickly and have reduced penetration or simply disintegrate on the target leaving you to face whatever it was you just shot with a serious reason to cause you harm. A bullet that it to strongly constructed my fail to expand at all. If it was originally of sufficient diameter this might not be too bad but if of a small initial diameter you may find yourself explaining your misdeeds to your target. Choose your bullets carefully.
My personal belief is if you have a rifle of a given caliber (say a .308 or .30-06), and you want (or need) something more powerful, what you need to do is to go up on either bullet diameter alone or bullet diameter and powder capacity and go to a .35 or so caliber. Don't waste your time burning more powder on a big bottle with the same bullet.
Of course, if you have lots of spare money and just have the need to have a whole bunch of different rifles to play with, be my guest. (...and you can send a couple to me so I can play too.)
I hope that the forgoing has provided some food for thought and I'm sure that I will be hearing from some of you. You can email your comments and ideas to me at [email protected].
|THE 4 RULES:
The 4 Basic Rules of Firearms Safety - If
these four basic safety rules are established and followed, safe firearms
handling will be assured and negligent discharges will be avoided.
THOMPSON, JOHN TALIAFERRO:
TIMED FIRE: is a type of pistol match or a stage of the national match course of fire where a string of five shots are fired consecutively during a period of 20 seconds. A timed fire match is a series of four such strings and the National Match Course includes two strings.
TIMING: The alignment of the chambers in a revolver with the bore. In a revolver which has seen a lot of use, the timing can be "off," so that the chambers do not perfectly align with the bore, causing the gun to spit lead from the barrel-cylinder gap. Timing is also important on many heavy and crew served machine guns like the Browning M2 .50 Caliber where the "Headspace and Timing" must be adjusted periodically to ensure proper ammunition feeding and function.
TOP STRAP: The upper part of a revolver frame, which often is either slightly grooved, the groove serving as the rear sight or which carries at its rearward end a sight that may be adjustable.
TOUCH HOLE: Small hole in a gun or cannon for igniting the charge.
TRACER: Slang for Tracer Ammunition.
TRACER AMMUNITION: A type of ammunition that utilizes a projectile or projectiles that contain a compound in its base that burns during its flight to provide a visual reference of the projectile's trajectory. While it may produce an incendiary effect on a target it is not expressly designed to do so. Caution must be taken when using Tracer Ammunition as range fires or brush fires can be easily started by the burning compound.
TRAJECTORY: The flight path of a projectile. The vertically curved path taken by a bullet after it leaves the barrel of a gun. Contrary to popular misconception it is not a straight line but rather a somewhat flattened curve that crosses the line of the sight twice.
TRAP: A shotgun shooting sport in which the competitors attempt to break frangible aerial targets going away from them at different angles and elevations. It is an Olympic shooting sport. The term can also refer to the device used to throw the frangible targets also know as Clay Targets, Clay Pidgins and Skeet.
Early American breech loading rifle where the breech block hinged
forward to open like a trap door. Specifically the term refers to:
U.S. SPRINGFIELD RIFLES &
CARBINES PRODUCED BETWEEN 1865 & 1893.
These single shot, black powder "breech loading" rifles were
initially manufactured by converting American Civil War vintage muzzle
loading rifles. "Trapdoor" rifles were carried by many of the United
States troops in the Spanish American War.
TRAP STOCK: A style of shotgun stock with greater length and less drop designed for trap shooting.
TRIGGER: A small lever protruding from the action. Pressing the trigger causes the cartridge to be fired.
TRIGGER CONTROL: is the ability of the pistol shooter to apply pressure on the trigger to fire the weapon without disturbing sight alignment.
TRIGGER GUARD: This is a loop of metal which extends down from the frame and encircles the trigger. It is designed to prevent the trigger from snagging as the firearm is handled or as handgun is removed from or placed into a holster. Some vintage handguns do not have trigger guards.
TRIGGER, HAIR: A slang term for a trigger requiring very low force to actuate. Note: Hair triggers are frequently used on competitive target rifles and pistols for increased accuracy. The reduced force needed to pull the trigger allows the shooter. s firearm to remain steady.
TRIGGER JOB: Polishing or machining work done to lighten the trigger pull.
TRIGGER LOCK: Trigger locks can be purchased in a variety of styles, all of which secure the handgun by immobilizing the trigger. The most common trigger lock design covers the trigger mechanism on either side with two steel or plastic blocks which lock together. Most major manufacturers have been giving away trigger locks with new handguns for the last few years. The locks can be purchased with either keyed or combination locks, and are designed to allow the handgun to be transported while locked. Most trigger lock designs are easy to use, however, the owner of the handgun must actively install a trigger lock. Trigger locks should never be placed on a loaded gun. For additional information see safety note below.
Some handgun owners may wish to use a trigger lock to secure a loaded gun. In such cases, the risk of unintentional [read negligent] discharge is significant when installing or removing a trigger guard from a loaded handgun. Reports of idiots negligently making there guns go bang while trying to put a lock on them come in often. NEVER put a trigger lock on a loaded firearm!
Most Firearms Manufacturers include a free trigger lock with the purchase of a firearm.
When properly installed on unloaded handguns, trigger locks can reduce the risk of unintended discharge. Trigger locks prevent children of any age from using the gun, as long as the child does not have access to the key or combination. Note: If the trigger lock does not fit the gun properly or is improperly installed, the trigger may still be operated.
Never put a trigger lock on a loaded firearm.
|TRIGGER PULL: Length
of the travel of the trigger. Force or weight in pounds needed
to engage the trigger. The average force
which must be applied to the trigger to cause the firearm to fire. Note:
Typically, non-target mode-firearms have a minimum trigger pull of 3
pounds. Double action revolvers often have a long, heavy trigger pull of
around 10 pounds.
TRIM TO LENGTH: The length a cartridge case should be trimmed to after it has stretched past its' "maximum case length".
TRITIUM: A radioactive isotope of hydrogen with atoms of three times the mass of ordinary light hydrogen atoms. Tritium, due to its radioactive properties, glows in the dark and is the most common element used in "night sights". Night sights are probably the most useful accessory on a combat handgun, as statistics show that 85% of gun fights occur in low light conditions or at night.
TURRET PRESS: A reloading press with a rotating multi-station turret top for positioning dies and powder measure in their appropriate sequence.
TWIST: The rate of spiral of the grooves of a rifle barrel expressed in length of barrel per revolution. 2. The pitch of a firearm's rifling expressed in a ratio of turns per distance. A 1:7 (1 turn in 7 inches) twist means that the rifling makes 1 complete turn in 7 inches. The optimum twist rate is determined by the projectile's length and diameter.
TWIST BARRELS: A process in which a steel rod (called a mandrel) was wrapped with "skelps" - ribbons of iron. The skelps were then welded in a charcoal fire to form one piece of metal, after which the rod was driven out to be used again. The interior of the resulting tube then had to be laboriously bored out by hand to remove the roughness. Once polished, the outside was smoothed on big grinding wheels, usually turned by water power.
TWIST RATES: The following is an explanation of the many twist rates found in AR-15 rifles barrels.
TMTW - 2MTW: Acronym for Two (2) Major Theater War. Current U.S. Military strategy that mandates and plans for the ability to deploy to, fight and win a major war in two (2) separate theaters or geographic locations simultaneously. The TMTW strategy and many other defense plans and procedures are under review.