Question: The ballistics of the .260 Remington are basically similar to a cartridge developed in what year?
Context: A lawyer and firearm enthusiast, Charles (Chas.)  Newton's experiments with cartridge design led to the creation of the .22 Savage Hi-Power rifle cartridge which was adopted by the Savage Arms Corporation as a commercial firearm cartridge.  This success was soon followed by the design of the .250-3000 Savage.  At this period in time, Charles also experimented with wildcats based on the .30-06 Springfield case, most notably creating a forerunner of the .25-06 Remington.  This cartridge was first introduced as the .25 Newton Special.  There were probably no firearms produced in this caliber by Netwon.  It soon evolved into the .256 Newton designed to use, at first, a 123 grain bullet followed by later upgrades to 129 grain and 140 grain bullets.  Newton's premise was to use a large case for each caliber he developed in order for the larger powder charge to propel the bullet at high velocity resulting in effective terminal ballistics.  Newton developed several calibers.  The best known are the .22 Newton (90 grain bullet), .256 Newton, .30 Newton (180 grain bullet), .33 Newton (200 grain bullet), .35 Newton (250 grain bullet) and .40 Newton (300 grain bullet).  From 1914 until the late 1920s, he entered into various endeavours to promote and sell rifles in his proprietary calibers. The .264 Winchester Magnum is a belted, bottlenecked rifle cartridge.  Apart from the .244 H&H Magnum and .257 Weatherby Magnum, it is the smallest caliber factory cartridge derived from the 2.85 in Holland & Holland belted magnum case.  It was introduced in the late 1950s and early 1960s with the .338 Winchester Magnum and the .458 Winchester Magnum as one of a family of short-cased 2.5 in belted magnum cartridges developed by Winchester based on the .375 Holland & Holland parent case.  It was officially introduced to the public by Winchester in 1959.  After many years of dwindling use it began enjoying a mild resurgence in popularity in the mid-2000s among long range rifle enthusiasts and reloaders due to the high ballistic coefficient of the heavier 6.5mm bullets and increasing popularity of cartridges such as 6.5mm Creedmoor, .260 Remington, 6.5 Grendel, benchrest and wildcat cartridges in 6.5mm. The 6.5×55mm (designated as the 6.5×55 Swedish by the SAAMI and 6,5 × 55 SE by the C.I.P.) is a first-generation smokeless powder rimless bottlenecked rifle cartridge.  Other, less common names are 6.5×55mm Swedish Mauser, 6.5×55mm Mauser and 6.5×55mm Krag.  It was developed in 1891 for use in the new service rifles then under consideration by the United Kingdoms of Sweden and Norway.  The two nations had independent armies and consequently the normal procedure at the time was for their respective governments to use the same ammunition and then purchase small arms of their choice.  Norway adopted the Krag–Jørgensen rifle, while Sweden adopted a Mauser rifle design. The .277 Wolverine (6.8×39mm) is a wildcat cartridge developed and marketed by Mark Kexel, President of Mad Dog Weapon Systems (MDWS).  It is a multi-purpose mid-power cartridge with increased ballistic performance over the AR-15's traditional .223 Remington (5.56×45mm NATO) cartridge requiring only a new barrel to upgrade/convert any 5.56-based firearm to .277 Wolverine. The 7mm-08 Remington is a rifle cartridge that is almost a direct copy of a wildcat cartridge developed around 1958 known as the 7mm/308.  As these names would suggest, it is the .308 Winchester case necked down to accept 7 mm (.284) bullets with a small increase in case length.  Of cartridges based upon the .308, it is the second most popular behind only the .243 Winchester.  However, the .308 is more popular than both.  In 1980, the Remington Arms company popularized the cartridge by applying its own name and offering it as a chambering for their Model 788 and Model 700 rifles. The .17 Mach IV is a wildcat centerfire rifle cartridge, based on the .221 Remington Fireball case, necked down to fire a .172 bullet.  The cartridge was introduced in 1962 by Vern O’Brien.  The cartridge offered an easy case conversion and good ballistics, but could not compete against the .17 Remington. 300 AAC Blackout, SAAMI short name 300 BLK, also known as 7.62×35mm is a rifle cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine.  Its purpose is to achieve ballistics similar to the 7.62×39mm Soviet cartridge in an AR-15 while using standard AR-15 magazines at their normal capacity.  Care should be taken not to use 300 BLK ammunition in a rifle chambered for .223/5.56 or 7.62×40mm Wilson Tactical. The .404 Jeffery is a large-caliber, rimless cartridge designed for large, dangerous game, such as the "Big Five" (elephant, rhino, cape buffalo, lion and leopard) of Africa.  Other names for this cartridge include .404 Jeffery Rimless, .404 Rimless Nitro Express, and 10.75× 73mm.  It was created by W.J. Jeffery & Co of England based on their desire to duplicate performance of the .450/400 (3¼") cartridge.  There are two basically similar sets of dimensions for this case, depending on the manufacturer.  The .404 Jeffery as originally loaded fired a .423" diameter bullet of either 300 gr with a muzzle velocity of 2600 ft/s and muzzle energy of 4500 ft.lbf or 400 gr with a muzzle velocity of 2125 ft/s and 4020 ft.lbf of energy.  It is very effective on large game and is favored by many hunters of dangerous game.  Performance and recoil are similar to other African dangerous game cartridges.  The .404 Jeffery was popular with hunters and game wardens in Africa because it gave good performance with a manageable level of recoil.  By way of comparison, the .416 Rigby and .416 Remington Magnum both fire a 400 grain .416 in bullet at 2400 ft/s with a muzzle energy of approximately 5000 ft.lbf , which handily exceeds the ballistic performance of the .404 Jeffery but at the price of greater recoil and, in the case of the .416 Rigby, rifles that are significantly more expensive. The .260 Remington (also known as 6.5-08 A-Square) cartridge was introduced by Remington in 1997.  Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round.  Although loaded to higher pressures, the ballistics of this cartridge are basically similar to the 6.5×55mm when bullet weights do not exceed 140 grains.  When loaded with heavier bullets, the 6.5×55mm is capable of greater velocity.  Due to its shorter overall length the .260 Remington can be chambered in a shorter length action than the 6.5×55mm. The 7mm BR Remington, commonly called the 7mm BR or the 7mm Benchrest Remington in long form, was a cartridge developed by Remington for the Remington XP-100 single-shot bolt-action handgun.  The cartridge was developed for the Unlimited Class in the sport of Metallic silhouette shooting.  Later it was introduced in the Remington Model XB-40 single-shot bolt-action rifle, which was specifically designed for the benchrest shooting community.
Answer: 1891