(dăm′ə-sēn′, dăm′ə-sēn′)

  • A form of decoration sometimes performed on firearms whereby very thin precious metal (normally gold) is hammered in artful designs directly onto the steel surface of the gun. Cheaper to accomplish, normally gaudier, and certainly less durable than gold inlay.
Damascus Barrels


  • Barrel tubes built up by twisting alternate strips of iron and steel around a fixed rod (mandrel) and forge-welding them together in varying combinations according to the intended quality and the skill of the maker. The rod was withdrawn, the interior reamed and the exterior filed until the finished tube was achieved. Damascus barrels may be recognized by any of a variety of twist or spiral patterns visible in the surface of the steel. Before the 20th century, barrels were typically built in this manner because gunmakers did not have the technology to drill a deep hole the full length of a bar of steel without coming out the side.
  • A gunmaker founded 1881 in St. Etienne, France, famous for its sliding-breech action. (Pronounced: darn, not darnay)
Date Codes
  • Amongst proof marks are codes enabling one to determine the date of manufacture of many guns
De Cocker
  • A type of action, usually of a break-open firearm, which readily allows release of mainspring tension, rendering the gun safe. In German: Handspanner.
Deeley Forend Release
  • A latch for securing the forend to the barrels of a break-open gun, operated by a short pull-down lever mounted to the center of the forend. Typically seen on Parker and Prussian Charles Daly guns. More properly known as a Deeley & Edge Fastener.
Delayed Blowback

(dĭ-lā′)   (blō′băk′)

A variant of the blowback principle in which the blowback operation is by some means retarded (e.g., by a fluted or grooved chamber). For more powerful rounds or for a lighter operating mechanism, some system of delayed or retarded blowback is often used, requiring the bolt to overcome some initial resistance while not fully locked. Because of high pressures, rifle-caliber delayed blowback firearms, such as the FAMAS and G3, typically have fluted chambers to ease extraction.

Gun Gas Delay Blow Back
Gun Gas Delay Blow Back



























Demi bloc Barrels
  • (called Chopper-lump barrels in British) - A method of joining the two separate tubes of a set of barrels where the right-hand half of the pair of lumps under the barrels are forged integrally with the right barrel and the left-hand half of the pair of lumps under the barrels are forged integrally with the left barrel. Chopper-lump barrels can be recognized by the fine joint-line running longitudinally down the center of each lump. This method of jointing barrels is the best because: 1. It is the strongest in relation to its weight, and 2. Because it allows the two barrels to be mounted closest to each other at the breech end, reducing problems regulating the points of aim of the two separate barrels.
  • Damage to a shotgun barrel from having taken a hit from a hard object. Thinner-walled barrels are more subject to the risk than thicker ones. While dents a few thousandths of an inch deep may not be dangerous, deeper ones ought to be raised by a skilled gunsmith before firing the gun, best done using a hydraulic dent-raising tool.


  • A small single-shot or multi-barreled (rarely more than two) pocket pistol. The design was first produced by Henry Deringer, under the brand name Deringer. When used to refer to any other brand of the same design, derringer is spelled with two r's and is not capitalized.


  • to cause (a bomb, mine, etc) to explode or (of a bomb, mine, etc) toexplode; set off or be set off
Diamond Grip
  • The cross-sectional shape at the wrist of a long gun, describing a soft diamond shape (as opposed to a circle or an oval) in the interest of comfort---and a better frame of reference for the gun's position.
  • A piece of tooling used to form a sequence of uniform parts through the use of heat and/or pressure; especially, in firearms terminology used to form brass cartridge cases accurately to their correct size for reloading.
Disc Set Strikers
  • Circular steel fittings, about 1/2 inch in diameter, screwed into the breech face of a gun and through which the firing pins pass. Firing pin bushings allow the convenient replacement of broken firing pins. They also allow the renewal of an older gun where, over the decades, leakage of high-pressure gas from corrosive primers has eroded the breech face around the firing pins; and replacing these bushings with new ones, slightly oversized can compensate for a situation where proper headspace has been compromised. In American: Bushed Firing Pins.


Most commonly, a device in auto pistols that prevent the pistol from being fired until the breech is completely shut and prevents the pistol from being fired fully automatic.



















Dog Lock
  • An early form of Flintlock, incorporating an external catch to lock the hammer
Dolls Head
  • A rib extension on a break-open gun, ending in a circular or semi-circular shape in plan (resembling the head of a doll), mating into a similarly-shaped recess in the top of the receiver, designed to resist the tendency of the barrels to pull away from the standing breech when firing. Because an action's centerpoint of flexing when firing is at the base of the standing breech, not at the hingepin, a passive doll's head extension makes an effective extra fastener, even without additional mechanical locks operated by the opening lever.

Dope of a Scope

dōp                     skōp

"A sniper will enter information into a data, or DOPE (Data On Personal Equipment) book, such as lot number, temperature, wind speed/direction, humidity and altitude. If the same conditions are encountered again, the data is available to assist in making an accurate shot."

After you zero the scope... doping is simply calculating the number of clicks from your zero, to account for bullet drop and drift at various ranges, for a specific ammunition load.

A DOPE has to be calculated for each ammo load that has different bullet weights and velocity.

Dope of a Scope Dope of a Scope

Doppelbüchs Drilling
  • German term for a three-barrel firearm comprising two side-by-side rifle barrels over one shotgun barrel.
Double Action

[¦dəb·əl ′ak·shən]

A type of lockwork in either a revolver or auto pistol that permits the hammer to be cocked either by direct manual action or by a long pull on the trigger. The term is extensively used (somewhat erroneously) as a synonym for "trigger cocking." Thus, such phrases as "The double-action pull was very smooth" or "The Seecamp is a double-action-only auto pistol."

Single & Double Action Revolvers Single & Double Action Revolver                                                              Double Action vs Single Action Double Action vs Single Action

Double Action DA
  • A type of firearm that may be discharged either by manually cocking the weapon and then pulling the trigger or by using trigger action to both cock and fire the weapon. Originally used only for revolvers but now common in semi-autos as well, Now it commonly means a revolver or pistol on which a long trigger pull can both cock and release the hammer to fire the weapon. In a revolver this action also rotates the cylinder to the next chambered round.
Double Action Single Action DA SA
  • A type of firearm that is designed to operate in double action on the first shot, and in single action on the second and subsequent shots.
Double Action Only DAO
  • Is a type of firearm in which the firing mechanism cannot be cocked in a single-action stage. Firing always occurs as a double-action sequence where pulling the trigger both cocks and then fires the gun.
Double Barrel
  •  A shotgun with two barrels either side by side or one over the other.
Double Feed
  • A malfunction in which the spent case fails to eject from a semi-automatic firearm and blocks the chamber. As the fresh round is brought forward it cannot enter the chamber. It is cleared by stripping the magazine from the gun, racking the slide several times to eject the spent case, and then reloading.
Double Rifle
  • Two independent rifles, built on one frame, designed to allow two virtually instantaneously quick, totally reliable shots. The barrels may be arranged either side-by-side or over-and-under. The apogee of the gunmaker's art. Particularly useful against dangerous game, which may be moving, and in your direction, with vengeance on its mind.
Double Rifle
  • Two independent rifles, built on one frame, designed to allow two virtually instantaneously quick, totally reliable shots. The barrels may be arranged either side-by-side or over-and-under. The apogee of the gunmaker's art. Particularly useful against dangerous game, which may be moving, and in your direction, with vengeance on its mind.
Double Tap
  • Two shots fired in rapid succession. Generally without getting a new sight picture on the target. If the second shot is fired after a second sight picture is captured it may instead be called a controlled pair.
  • The unwanted tendency for a double barreled gun to fire both barrels virtually simultaneously---the recoil from the first barrel's discharge jarring the sear for the second barrel of its notch, causing it, too, to fire. The result of worn parts, coagulated old oil or unskilled maintenance..
Dovetailed Barrels
  • The usual way of building a set of side-by-side barrels. Two raw tubes are filed to approximate their final contour. A solid block of steel is then filed to shape, fitted between the two tubes at the breech end with about 3/4" exposed on the underside and soldered or brazed into place to form the lump(s).
Down Range
  • The area of a gun range where firearms are pointed when they are fired. The area of the range forward of the firing line.


  • A unit of measure traditionally used for black powder shotgun charges. Today, used for smokeless powders on the basis of the new propellant's equivalent performance to that weight of black powder. Thus, a shotgun shell marked 3 - 1 1/8 would be loaded with the smokeless powder equivalent of 3 drams of black powder, and with 1 1/8ounce of shot. 1 Dram = 1/16 ounce = 437.5 grains.
  • A three-barrel shoulder-fired gun, typically with two identical side-by-side shotgun barrels mounted above one rifle barrel. Built primarily in Germany and Austria. If with two rifled barrels above a single rifled barrel, it is called a Bock Drilling
Driving Bands

(drī′vĭng)  (bănds)

Portions of a bullet's bearing surface that actually contact the bore. Driving bands are separated by crimping and lubrication grooves.  In a small-arms rifle, the entire bullet is typically covered in copper or a similarly soft alloy, so the entire bullet is its own driving band.

Bullet Driving Bands
Bullet Driving Bands














  • The distance from an imaginary straight line of sight extended along the rib of a shotgun rearward towards the butt---to the top of the stock at the comb or the heel. (In British: Bend). The amount of drop determines how high or how low a gun will naturally point. Browning, in its infinite wisdom, considers that 2 3/8" drop at the heel will best fit the broadest range of shooters for field use. This measurement can therefore be considered "normal." A gun with less drop will shoot higher, while a gun with more drop will shoot lower for a given individual. When the gun is comfortably mounted with the cheek snugly on the comb, the drop is about right when you can see the front bead and just a little rib over the standing breech. Trap guns usually have less drop because they are supposed to shoot a little high in order to hit an almost universally rising target. Standard wisdom indicates that the drop is about right for a mounted trap gun when the front bead seems to rest just on top of the middle bead like two parts of a snowman, or forming a figure-eight.
Drop Box Magazine
  • An extra-deep magazine typical of large caliber rifles for dangerous game. The line of the underside of the wrist does not carry straight forward as with ordinary rifles. Rather the rear of the magazine aligns more towards the center of the forward edge of the trigger-guard, typically allowing at least one extra cartridge to be carried.
Drop Points
  • Small, raised-carved details on either side of a double gun, behind the lockplates of a sidelock or behind the flat sidepanels of a boxlock, in the shape of a hanging drop of water. Also called teardrops.
Drop Safety
  • A mechanical safety that prevents the gun from firing when it is unintentionally dropped. Some state governments require drop-testing of all handgun designs sold within the state.
  • A variation on the Anson & Deeley boxlock design, introduced by Westley Richards at the end of the 19th Century, whereby the locks themselves are removable, without tools, from the action body for cleaning or repair through a hinged or a detachable floorplate. A droplock action may be distinguished from an ordinary Anson & Deeley action at sight because it has no action pins visible on the side of the receiver.
Dry Fire
  • To pull the trigger and release the hammer of a firearm without having a cartridge in the chamber. While benign enough with a Mauser action, it can shatter the differentially-hardened internal parts of a break-open gun which, upon firing, are designed to have the shock of the hammer's blow absorbed somewhat by the soft brass of the primer. If you must experiment with the trigger(s) and the action of a fine double gun, be sure to use snap caps---which safely replicate the buffering effect of an actual cartridge.
DST or Double Set Trigger
  • On a rifle, optionally pulling the rear (set) trigger converts the front (main) trigger to a light, hair trigger---too light and sensitive to be carried safely in the field. While the front trigger is always at the ready, if one has the time, using the set trigger feature may allow for a more accurate long-distance shot. Operates using its own miniature firing mechanism (sear, spring and hammer) when cocked, to multiply the force of a pull on the main trigger.

DT or Double Triggers
  • One for each barrel. Double triggers are better than single triggers on a double gun because:  1. They are simpler in design, therefore making the gun lighter and more reliable.  2. They are less prone to double-firing.  3. In the hands of an experienced shooter they are faster.  4. They allow immediate selection of which barrel to fire - the immediate selection of the pattern to throw - even while the grouse is flushing
  • A round of ammunition that does not fire.
Duelling Pistol

(do͞o′əl, dyo͞o′-)

  • Single shot pistols, of a design originating in England, in vogue circa 1770 - 1850, built necessarily in pairs, either of flintlock or percussion ignition, usually finely made and cased together with loading accessories. Dueling pistols tended to be lighter and sleeker than their contemporary service pistols. They tended to have smoothbore (or sometimes secret, scratch-rifling), octagon (or octagon-to-round) barrels around nine or ten inches long of some form of damascus steel, bores just over a half-inch, ramrods, rudimentary sights front and rear, single-set triggers, roller-bearing frizzens and curved grips integral with full or half-stocks. They were usually of high quality construction, sometimes with silver furniture, but normally of relatively plain decoration.
Dummy Round
  • An inert ammunition-shaped object, used in practice to simulate misfeeds and other malfunctions and also used in dry fire practice.
Dust Cover
  • A small hinged or sliding door covering the ejection port of a firearm to prevent detritus from clogging the works.