The Dardick tround, or simply tround (triangular round), is a unique firearms cartridge developed by inventor David Dardick for use in his open-chamber firearms. Named for its convex triangular shape, the tround allowed the firearm's chamber to be open on one side, removing the requirement for reciprocating motion when chambering and ejecting a cartridge.
It was used in several revolvers: the 10-tround Dardick Model 1100, the 11 or 15-tround Model 1500 - and the 20-tround Model 2000.
Dardick (an associate of Melvin M. Johnson) began development of his open-chamber gun in the late 1940s. Dardick's patent 2,847,784, issued in August 1958, is for a pre-stressed open-chamber gun with rotatable cylinder. Essentially this design was a revolver with the exterior of the chambers opened up, forming an open U shape rather than a closed O shape found on typical revolvers. This allowed cartridges to be inserted from the side of the cylinder, rather than from the front or rear, and allowed the cylinder to be rapidly loaded from a magazine.
To contain the pressure of firing, an odd number of chambers (typically three) are milled into the cylinder. The cylinder is placed, centered, in a strong frame, so that when ready to fire, the cartridge rests against one side of the frame, and the opposite side of the cylinder rests against the opposite side of the frame. Upon firing, the force is spread to the frame from the cartridge on one side and the cylinder from the other. The pre-stressed part of the design applies to the frame; it is assembled from two parts, which are machined so that the exterior part must be heated, thus expanding, before the interior part can be inserted. Upon cooling, the exterior part contracts, putting the interior frame under compression. This compression counters the pressure put upon the frame by firing.
Unlike a traditional firearms cartridge, whose case is roughly cylindrical, the open chamber requires the cartridge to be otherwise. Since the cartridge contacts the frame upon firing, one side of the cartridge must match the curvature of the cylinder's exterior, while the other side of the cartridge must match the half-chamber of the cylinder. Together, the cylinder and frame form the chamber, and the cartridge must not only fit in this space, but also must seal it upon firing, and not deform to prevent cylinder rotation.
At this point the rounds are not the familiar three sided shape seen in Dardick's production firearms. They are, rather, cylindrical on one side (the side facing the cylinder axis) and nearly flat on the other (the side facing the frame). This patent defined the open-chamber gun concept, however, and quickly led to the development of the tround.
During the 1950s U.S. military experiments with feeding devices for machine guns found that triangular cartridge cases would stack into 50 percent less space than conventional round cartridge casings. Due to problems in reliably feeding a triangular cartridge from a magazine into a triangular chamber in a gun barrel, the concept was not further pursued. [1]
Dardick's patent 2,865,126, issued in late 1958, is for a new and improved cartridge for the open-chamber gun. Unlike the previous open-chamber cartridge, this version shows the symmetrical tround shape, which would facilitate feeding from a magazine, since the trounds can enter the split in any orientation and end up seating correctly. This reduced the complexity and cost of the open-chamber firearm design, making it feasible for commercial production. The trounds were constructed of either high-strength plastic or aluminum to provide strength. [2] While trounds were only commercially available as cartridges suitable for handguns, prototype military trounds were made in larger calibers.
While trounds could be complete firearms cartridges, many trounds were made as chamber adapters which held a standard cartridge, such as a .38 Special. [3] This allowed readily available ammunition to be loaded into the trounds and fired from Dardick's guns. The .22 caliber tround held standard rimfire ammunition, and the guns that could fire it were equipped with a selectable firing pin to handle centerfire trounds or trounds loaded with rimfire cartridges.
Dardick's patent 3,855,931, issued in 1974, expands the tround to hold multiple projectiles, firing through a set of barrels (one per projectile), making a Project SALVO–type gun. This type of tround, holding three projectiles, was used in the H & R Firearms SPIW prototype. However it was rejected due to issues with weight (due to the three barrels) and strength of the tround when used with the high-velocity flechette ammunition. [4]
The Tround Terra-drill is described in patent 4,004,642, issued to Dardick in 1977. The Terra-drill is a drill head that combines a traditional drill bit with the SALVO tround. The tround is used to break through hard spots that the drill bit cannot readily penetrate. This version uses four ceramic bullets, which shatter upon impacting the rock, and which in turn are intended to fracture the rock to allow the drill bit to proceed. The tround is designed such that each projectile impacts the target at a slightly different time, imparting multiple shocks to create constructive interference of the shock waves in the target material.
The Dardick firearms were essentially revolvers whose unique open chambers could be reloaded from a magazine. The operating principle used was the same as a double-action revolver, with a long trigger pull serving to rotate the cylinder, cock, and release the hammer. Since the commercial trounds had the same exterior dimensions, the same firearm action would, by using a different barrel, chamber any of the calibers the trounds were chambered in.
The Dardick Model 1100 had a 10-tround magazine, and was only available chambered in .38 Dardick Tround (9 mm). [5] The Model 1500 came with interchangeable barrels, and was available in .38 (9 mm), .30 (7.62 mm), and .22 (5.56 mm) trounds, with a carbine conversion kit also available in .38 and .22. The Model 1500 could be configured to hold 11 or 15 trounds, and came with 4- or 6-inch barrel lengths. [6] A Model 2000 with a 20-tround capacity is also reported to exist. All versions used a non-removable magazine, which could be loaded with stripper clips or one tround at a time. [7] The Dardick revolvers proved to be a commercial failure, despite being, in the words of one reviewer, "as versatile as a six-armed monkey". [8]
A revolver is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers for firing. Because most revolver models hold up to six cartridges, before needing to be reloaded, revolvers are commonly called six shooters.
A cartridge, also known as a round, is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often used to refer to a complete cartridge, the correct usage only refers to the projectile.
In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pressure gas(es) is used to propel a projectile out of the front end (muzzle) at a high velocity. The hollow interior of the barrel is called the bore, and the diameter of the bore is called its caliber, usually measured in inches or millimetres.
The Desert Eagle is a gas-operated, semi-automatic pistol known for chambering the .50 Action Express, the largest centerfire cartridge of any magazine-fed, self-loading pistol.
The .45 Colt (11.43×33mmR), is a rimmed, straight-walled, handgun cartridge dating to 1872. It was originally a black-powder revolver round developed for the Colt Single Action Army revolver. This cartridge was adopted by the U.S. Army in 1873 and served as an official US military handgun cartridge for 19 years, before being replaced by the .38 Long Colt in 1892.
A magazine, often simply called a mag, is an ammunition storage and feeding device for a repeating firearm, either integral within the gun or externally attached. The magazine functions by holding several cartridges within itself and sequentially pushing each one into a position where it may be readily loaded into the barrel chamber by the firearm's moving action. The detachable magazine is sometimes colloquially referred to as a "clip", although this is technically inaccurate since a clip is actually an accessory device used to help load ammunition into a magazine or cylinder.
The Special Purpose Individual Weapon (SPIW) was a long-running United States Army program to develop, in part, a workable flechette-firing "rifle", though other concepts were also involved. The concepts continued to be tested under the Future Rifle Program and again in the 1980s under the Advanced Combat Rifle program, but neither program resulted in a system useful enough to warrant replacing the M16.
The Colt Army Model 1860 is a cap & ball .44-caliber single-action revolver used during the American Civil War made by Colt's Manufacturing Company. It was used as a side arm by cavalry, infantry, artillery troops, and naval forces.
In breechloading firearms, an extractor is an action component that serves to remove spent casings of previously fired cartridges from the chamber, in order to vacate the chamber for loading a fresh round of ammunition.
The GP100 is a family/line of double action five-, six-, seven-, or ten-shot revolvers made by Sturm, Ruger & Co., manufactured in the United States. Since its introduction, it has been produced with a number of variations including various barrel lengths and profiles, fixed or adjustable sights, and in blued carbon steel or stainless steel.
Break action is a type of firearm action in which the barrel(s) are hinged much like a door and rotate perpendicularly to the bore axis to expose the breech and allow loading and unloading of cartridges. A separate operation may be required for the cocking of a hammer to fire the new round. There are many types of break-action firearms; break actions are universal in double-barreled shotguns, double-barreled rifles, combination guns, and are commonly found in single shot pistols, rifles, shotguns, including flare guns, grenade launchers, air guns, and some older revolver designs. They are also known as hinge-action, break-open, break-barrel, break-top, or, on old revolvers, top-break actions.
The Remington-Beals Model Revolvers along with subsequent models and variations were percussion revolvers manufactured by Eliphalet Remington & Sons in .31 (Pocket) .36 (Navy) or .44 (Army) caliber, used during the American Civil War, and was the beginning of a successful line of medium and large frame pistols. They are commonly, though inaccurately, referred to as the Model 1858 due to the patent markings on its New Model barrels, "PATENTED SEPT. 14, 1858/E. REMINGTON & SONS, ILION, NEW YORK, U.S.A./NEW MODEL."; although wide scale production did not start until 1861.
A handgun is a firearm designed to be usable with only one hand. It is distinguished from a long gun which needs to be held by both hands and braced against the shoulder. Handguns have shorter effective ranges compared to long guns, and are much harder to shoot accurately. While most early handguns are single-shot pistols, the two most common types of handguns used in modern times are revolvers and semi-automatic pistols, although other handguns such as derringers and machine pistols also see infrequent usage.
In firearms, the cylinder is the cylindrical, rotating part of a revolver containing multiple chambers, each of which is capable of holding a single cartridge. The cylinder rotates (revolves) around a central axis in the revolver's action to sequentially align each individual chamber with the barrel bore for repeated firing. Each time the gun is cocked, the cylinder indexes by one chamber. Serving the same function as a rotary magazine, the cylinder stores ammunitions within the revolver and allows it to fire multiple times before needing to reload.
The following are terms related to firearms and ammunition topics.
A paper cartridge is one of various types of small arms ammunition used before the advent of the metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and in some cases, a primer or a lubricating and anti-fouling agent. Combustible cartridges are paper cartridges that use paper treated with oxidizers to allow them to burn completely upon ignition.
The .500 S&W Magnum or 12.7×41mmSR is a .50 caliber semi-rimmed revolver cartridge developed by Cor-Bon in partnership with the Smith & Wesson "X-Gun" engineering team for use in the Smith & Wesson Model 500 X-frame revolver and introduced in February 2003 at the SHOT Show. From its inception, it was intended to be the most powerful handgun cartridge to date, with the capacity to harvest all North American game species. While more powerful handgun cartridges, such as the .500 Bushwhacker, have emerged since, they are only available in custom firearms, and the .500 S&W remains the most powerful production handgun cartridge.
The Colt Open Top Pocket Model Revolver was a single action pocket revolver introduced by the Colt's Patent Fire Arms Manufacturing Company in 1871. Introduced a year before the Colt Open Top and two years before the Colt Peacemaker and the Colt New Line, the Colt Open Top Pocket Model Revolver was, alongside the Colt House Revolver, one of the two first metallic cartridge rear-loading revolvers manufactured by Colt's. It also was one of the first pocket metallic cartridge revolvers made by the company.
A repeating firearm or repeater is any firearm that is capable of being fired repeatedly before having to be manually reloaded with new ammunition into the firearm.