Calibre Confusion | The Delta Mike Ammunition Guide

As you begin to research calibre options for your next firearm you need to understand that ammunition cartridge names are non-standardised. By this, we mean that variables such as diameter, bullet length, shape and density, casing dimensions, and powder quantity appear in ammunition naming, if and when they do, inconsistently. Typically only projectile diameter is indicated in a projectile name and even these can be misleading at times!

To help illustrate, a classic example is the .30-30 Winchester and the .30-06 Springfield. The .30-30 Winchester is a .308-inch projectile in a cartridge designed and produced by Winchester. For this round, the -30 suffix represents the standard 30-grain charge weight. Now compare this with the .30-06 Springfield. Again, we have a .308-inch diameter projectile, but what differs is that for the .30-06, the -06 suffix is not related to the charge weight but refers to the adoption and production of the cartridge in 1906! As you can see, this is a completely different unit of measurement and even the true dimensions of the projectile are concealed behind a generic .30 Cal label.

To help you out, what follows in this article is some key information on certain calibres that Delta Mike LTD stocks firearms and ammunition for. We are happy to discuss calibre options with you should you require advice. Jump to a particular section with quick-links below:

Rimfire Ammunition

17 HMR

The .17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by Hornady in 2002. It was developed by necking down a .22 Magnum case to take the smaller .17 calibre (4.5 mm) projectile. In creating this round, Hornady was aided by Marlin and Ruger and together they sought to produce the highest velocity possible in a rimfire cartridge consistent with reliability, accuracy, and manufacturing economy. The round was designed to outperform the .22 WMR in being less susceptible to wind drift, having a similar range and noise, less susceptible to ricochet, operate at the same pressure, all while producing a standard 1-minute angle (MOA) or better accuracy.

.17 HMR Cartridge

The 17 HMR is suitable for small game hunting applications for a much longer range than a 22LR or similar. When loaded with a 17 grain (1.1 g) projectile, the 17 HMR can deliver muzzle velocities in excess of 2,650 ft/s 775 m/s (775 m/s). Typically, cartridges for .17 HMR come with bullet weights of 15.5 grains (1.00 g), 17 grains (1.1 g), or 20 grains (1.3 g). Cartridge options include plastic-tipped projectiles, hollow points, soft points, and FMJs (Full Metal Jacket) depending on application needs.

22 LR

The .22 Long Rifle is a long-established variety of .22 calibre rimfire ammunition that most likely originated as early as 1884 from the American cartridge manufacturer Union Metallic Cartridge Company. The round is used in a wide range of rifles, pistols, revolvers, smoothbore shotguns, and submachine guns. It combined the case of the .22 Long of 1871 with a 45-grain (2.9 g) bullet, giving it a longer overall length, a higher muzzle velocity and superior performance as a hunting and target round and as a result, almost rendered the original .22 Long obsolete. The .22 LR uses a heeled bullet meaning that the bullet is the same diameter as the case, and has a narrower “heel” portion that fits in the case.

.22 LR Cartridge

The .22 LR is effective to 150 yds (140 m), though practical lethal distance for hunting tends to be less in user experience. After 150 yds, the ballistics of the round are such that it is difficult to compensate for the large drop-off. The accuracy of the cartridge is good, but not exceptional, and various cartridges are capable of the same or better accuracy. A contributing factor to the accuracy of the .22 LR is the transition of even a high-velocity cartridge projectile from supersonic to subsonic within 100 yds (91 m). As the bullet slows, the shock wave caused by supersonic travel overtakes the bullet and can disrupt its flight path, causing minor but measurable inaccuracies. Yet despite these things, especially the relatively short effective range, advantages such as the low report, light recoil and low price the 22 LR is a world favourite for use as a target-practice cartridge or for close range, small game hunting.

22 MAGNUM

The .22 Winchester Magnum Rimfire, also called the .22 WMR, .22 Magnum, .22 WMRF, .22 MRF, or .22 Mag, is a rimfire ammunition cartridge. The .22 WMR was introduced in 1959 by Winchester and was the only really successful rimfire cartridge introduced in the 20th century. The .22 Magnum usually comes in bullet weights ranging from 50 grains (3.2 g) travelling at 1,530 feet per second (470 m/s) to 30 grains (1.9 g) coming in at an notable 2,200 feet per second (670 m/s).

.22 WMR Cartridge

The .22 WMR uses bullets comparable in weight to the .22 Long Rifle but is a considerably more powerful round providing much-improved penetration and more reliable expansion at longer ranges with expanding bullets. The round shoots flatter and farther and hits harder at all ranges. For comparison, the 40-grain (2.6 g) .22 WMR at 100 yards (91 m) still has 50% more kinetic energy than a 40-grain (2.6 g) .22 LR at the muzzle. The .22 WMR has an effective range of nearly 125 yards (114 m) making it an ideal step up from the .22LR as an effective short to medium range varmint hunting cartridge but does come in at a higher price.

Centrefire Ammunition

22 HORNET

The .22 Hornet (5.6×35mmR) is a small-game hunting and competition centerfire rifle cartridge commercially introduced in 1930. It is considerably more powerful than both rimfire .22 WMR and .17 HMR cartridges, achieving higher velocity with a bullet around twice the weight of the .17 HMR projectile. The Hornet also differs very significantly from these in that being a centerfire cartridge makes it reloadable, and thus much more versatile round for shooters.

.22 Hornet Cartridge

Factory ammunition is widely available from all major manufacturers, with projectiles generally weighing 34, 35, 45, or 46 grains (2.2, 2.3, 2.9, or 3.0 g), with hollow or soft point variations. Muzzle velocity typically is in the 2,500 to 3,100 ft/s (760 to 940 m/s) range, and muzzle energy is just over 700 ft·lbs (950 J) for factory ammunition. Velocity in the .22 Hornet, like most cartridges, is hugely affected by barrel length.

223 REMINGTON

The .223 Remington is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command of the United States Army as part of a project to create a small-calibre, high-velocity firearm. In the US Army, the cartridge is referred to as the “5.56 mm ball M193”. The .223 Remington is one of the most popular cartridges in the world and is currently used by a wide range of semi-automatic and manual-action rifles. The popularity of the .223 Remington meant it soon dominated all other similar .22 calibre centre-fire varmint rifle cartridges. A well placed .223 shot is sufficiently lethal for medium to large game hunting.

.223 Remington Cartridge

The 5.56×45mm NATO was developed from the 223 Remington footprint. Yet the .223 Remington and 5.56×45mm NATO barrel chamberings are not the same. While the cartridges are identical other than powder load, bullet weight, and resulting chamber pressure, 5.56x45mm rounds should not be fired through a .223 Remington chambered rifle. However, due to slightly lower pressures, a .223 Rem cartridge can be safely fired through a rifle chambered to 5.56x45mm and often .223 Rem rifles are advertised as being chambered for the near-identical military spec’d round.

6.5 CREEDMOOR

The 6.5mm Creedmoor (6.5×48 mm) is a centerfire rifle cartridge introduced by Hornady in 2007. It was developed by Hornady senior ballistics scientist Dave Emary in partnership with Dennis DeMille, the vice-president of product development at Creedmoor Sports, hence the origins of the name. The 6.5mm Creedmoor was designed specifically for long-range target shooting but has succeeded in the market as a popular hunting round also. One standout feature of the cartridge is that due to its overall length of 2.825″ (71.8 mm), the round is capable of chambering in short-action rifles.

6.5mm Creedmoor Cartridge

A 6.5 Creedmoor 129-grain Hornady SST projectile at 300 yards can reach 1,641 foot-pounds force (2,225 J). And for a 140-grain projectile travelling at 2,700 feet per second, one reviewer reported an MPBR (Maximum Point Blank Range) for a six-inch-high target of 265 yards (242 m). 6.5mm Creedmoor can provide sub-half-minute angle accuracy from factory ammo. The cartridge stays supersonic and maintains an accurate flight path past 1,200 yds (1,097 m) making it an impressive option for long-range shooting.

270 WINCHESTER

The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923 and was unveiled in 1925 as a new chambering for their bolt-action Model 54. The .270 Winchester is a suitable cartridge for hunting large game and is well purposed for plains and mountain hunting. The .270 Win is a long-action cartridge and the optimum barrel length is generally considered to be 24 inches. However even with a 22-inch barrel muzzle velocity remains measurable, making it a suitable cartridge for a lightweight mountain rifle with a shorter barrel.

.270 Win Cartridge

Loaded with a 130-grain bullet, the .270 Win can reach around 3060 fps (932m/s). And with correct sighting in shooters can expect a maximum point-blank range of around 325 yards (297 meters) for a 7-inch diameter target, matching the vital area of the deer-sized game. Thus, a skilled hunter can shoot within MPBR without having to think about compensating for bullet drop. And given that a .270 cartridge loaded with the 130-grain bullet will also retain 1500 ft-lb. of energy up to 365m, still maintains what is considered the minimum suitable killing force for large game such as deer.

7mm-08 Remington

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 indicated in the name, this cartridge is a .308 Winchester case necked down to accept 7mm (.284″) projectiles with an additional small increase in case length. Of cartridges based upon the .308, it is typically just behind .243 Winchester in popularity. However, the .308 Winchester remains more popular than both worldwide.

.7mm-08 Cartridge

With the wide range of projectile weights available, the 7mm-08 is suitable for medium to large game hunting, and long-range target shooting. The 7mm-08 Remington performs well in most hunting environments, including dense forest areas and in particular, large open fields. It has a flatter trajectory than the .308 Winchester and .30-06 Springfield at similar projectile weights because the slightly smaller-diameter 7mm bullet generally has a better ballistic coefficient, and is thus less affected by in-flight drag and crosswind. The 7mm-08 bullet trajectory is comparable to that of the .270 Winchester.

300 BLACKOUT

The .300 AAC Blackout (7.62×35mm) is a rifle cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. The cartridge yields increased performance in shorter barrels and effective sub-sonic performance for suppressor use when compared to .223 Rem/ 5.56mm NATO. The 300 AAC Blackout utilizes standard .223/ 5.56mm NATO magazines with the exception of the barrel.

.300 Blackout Cartridge

The .300 Blackout has an effective range of roughly 460 meters, being capable of penetration through several inches of different hard targets. The cartridge is also highly versatile and allows users to have one firearm with the capability of switching between subsonic, supersonic VMAX or barrier penetrating ammunition all with just the change of a magazine with varied loads.

300 WINCHESTER MAGNUM

The .300 Winchester Magnum (7.62×67mmB, 7.62x66BR) is a belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms Company in 1963. The cartridge is based on the .375 H&H Magnum, which has been blown out, shortened, and necked down to accept a .30 calibre (7.82 mm) bullet.

.300 Win Mag Cartridge

The .300 Winchester is extremely versatile and has been adopted for a wide array of applications including hunting, target shooting, military units, and law enforcement departments. Hunters found the cartridge to be an effective all-around choice with bullet options ranging from the flatter shooting 165 grain to the harder-hitting factory available 200+ grain options. The .300 Win Mag remains the most popular .30 calibre magnum with hunters, despite being surpassed in performance by the more powerful .300 and .30-378 Weatherby Magnums and the newer .300 Remington Ultra Magnum. The calibre is well suited to delivering lethal killing power to large game and offers superior long-range performance than most other .30 calibre cartridges. Military and law enforcement departments adopted the cartridge for long-range sniping and marksmanship as a testament to its accuracy, and since the introduction of the round to the market, has gone on to win several 1,000-yard (910m) competitions.

308 WINCHESTER

The .308 Winchester is one of the most popular hunting cartridges in the world and is an exceptional cartridge for medium to large-sized game. The relatively short case makes the .308 Winchester especially well-adapted for short-action rifles making it a favourite with hunters. When loaded with a projectile that expands, tumbles, or fragments in tissue, this cartridge is capable of powerful high terminal performance.

.308 Winchester Cartridge

Although not identical, the .308 Winchester and military 7.62×51mm NATO cartridges are similar enough that they can be loaded into rifles chambered for the other round, but the .308 Winchester cartridges are typically loaded to higher pressures than the 7.62×51mm (opposite therefore to the .223 Rem/ 5.56x45mm NATO example). Even though the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) does not consider it unsafe to fire the commercial .308 Winchester rounds in weapons chambered for the military 7.62×51mm NATO round, there remains significant discussion about compatibility due to differing chamber pressures, cartridges, powder loads, chamber dimensions and wall thicknesses in the web area of the military round compared to commercial cartridge cases.

350 LEGEND

The .350 Legend (9×43 mm), is a SAAMI-standardized straight-walled hunting cartridge developed by Winchester Repeating Arms and revealed at the 2019 SHOT Show in Las Vegas, Nevada. The cartridge was designed for use in American states that have specific regulations for deer hunting with straight-walled centerfire cartridges and has a maximum effective range of 250 yards (230 m). With a 160 gr (10 g) Federal Fusion projectile the .350 Legend can achieve 2,300 ft/s (700 m/s) velocity and 1,879 ft-lb (2,548 J) of energy.

.350 Legend Cartridge

The .350 Legend shares many characteristics with the .223 Rem/ 5.56 mm NATO, the overall cartridge length is 2.26 inches (57 mm) long with a rim diameter of .378 inches (9.6 mm), but it is not derived from the .223 Remington. Because of its similarities to the .223 Remington and the .350 Legend is suitable for use in AR-15 platform rifles and will fit in most standard AR-15 magazines without modification.

450 BUSHMASTER

The .450 Bushmaster is a rifle cartridge developed by Tim LeGendre of LeMag Firearms and licensed to Bushmaster Firearms International. The .450 Bushmaster is descended from the “Thumper concept” popularized by gun writer Jeff Cooper. Cooper was dissatisfied with the small-diameter 5.56×45mm NATO (.223 Remington) of the AR-15 and envisioned a need for a large bore (.44 cal or greater) cartridge in a semi-automatic rifle to provide one-shot kills on big-game animals at 250 yards. Inspired by this, LeGendre developed his .45 Professional cartridge, and later built and delivered an AR-15 in .45 Cal. At the muzzle, the cartridge can pitch a 250-grain bullet at 2,214 fps, a fair go for a .452″ projectile!

.450 Bushmaster Cartridge

The .450 Bushmaster makes use of .452″ bullets because the lower impact velocities and energies would not adequately expand the heavier jacketed .458″ bullets. The cartridge is chambered in bolt-action rifles by Ruger, Savage, Mossberg, and Remington, Ruger’s No. 1 single-shot rifle and AR-15 rifles. Ballistically, the .450 Bushmaster has a rather flat trajectory out to 200 yards; if the firearm is zeroed at 150 yards, the user can expect to see a rise of 1.8 inches at 100 yards, zero at 150 yards, and a drop of 4.9 inches at 200 yards.

Handgun Ammunition

9MM LUGER

The 9×19mm Parabellum (or 9mm Luger) is a rimless, tapered firearms cartridge. When shooters refer to “9mm” in the generic sense, they mean the 9x19mm despite other 9mm variations existing. Originally designed by Austrian firearm designer Georg Luger in 1901, the 9mm is the most popular handgun and submachine gun round available due to its low cost and extensive availability. It is a standard issue cartridge for NATO forces as well as in many non-NATO countries. The round was originally designed to be lethal to 50 metres (160 ft) but is still lethal at longer ranges. The cartridge combines a flat trajectory with moderate recoil.

9×19mm Cartridge

38 SUPER

The .38 Super, (38 Super +P, .38 Super Auto, .38 Super Automatic, .38 Super Automatic +P, or 9×23mmSR) is a pistol cartridge that fires a 0.356-inch-diameter (9.04 mm) bullet. It was introduced in the late 1920s as a higher pressure loading of the .38 ACP, also known as .38 Auto. The older .38 ACP cartridge propels a 130-grain (8.4 g) bullet at 1,050 ft/s (320.0 m/s), whereas the .38 Super pushes the same bullet at 1,280 ft/s (390.1 m/s). The .38 Super has gained distinction as the calibre of choice for many top practical shooting competitors; it remains one of the dominant calibres in IPSC competition.

.38 Auto Cartridge

Because of its larger case volume, which allows for more smokeless powder and results in higher muzzle velocities at similar pressure levels, the .38 Super offers higher bullet velocity potential than the 9×19mm Parabellum when hand loaded and in some defence loadings. 115 Gr (7.5 g) full metal jacket: 1,405 feet per second (428 m/s). 124 Gr (8.0 g) full metal jacket: 1,350 feet per second (410 m/s).

44 MAGNUM

The .44 Remington Magnum, also known as .44 Magnum or 10.9x33mmR, is a rimmed, large-bore cartridge originally designed for revolvers and quickly adopted for carbines and rifles. Despite the “.44” designation, guns chambered for the .44 Magnum round, and its parent, the .44 Special, use 0.429 in (10.9 mm) diameter bullets. The .44 Magnum is based on the .44 Special case but lengthened and loaded to higher pressures for greater velocity and energy. Famously called “the most powerful handgun [cartridge] in the world” by Clint Eastwood in Dirty Harry, the .44 Magnum has since been eclipsed in power by the .454 Casull, .460 S&W Magnum, .480 Ruger, .50 Action Express, and .500 S&W Magnum; nevertheless, due in part to more manageable recoil it has remained one of the most popular commercial large-bore magnum cartridges.

.44 Magnum Cartridge

The accuracy of the .44 Magnum is extremely good, with models from Colt, Smith & Wesson, and Ruger producing bullet groups of 3 to 4 inches (7.6 to 10.2 centimetres) at 50 yards (46 m), with most ammunition. The limiting factor of the .44 Magnum cartridge is not terminal ballistics. When fired from a 6 in (150 mm) revolver, a typically loaded .44 Magnum 240 gr (16 g) bullet will have more impact energy at 150 yds (140 m) than a 246 gr (15.9 g) .44 Special has at the muzzle, when fired from the same weapon.

The .44 Magnum was an immediate success, and the direct descendants of the S&W Model 29 and the .44 Magnum Ruger Blackhawks are still in production and have been joined by numerous other makes and models of .44 Magnum revolvers and even a handful of semi-automatic models, the first being produced in the 1960s. The .44 Magnum delivers a large, heavy bullet with high velocity for a handgun. In its full-powered form, it produces so much recoil and muzzle blast that it is generally considered to be unsuitable for use as a police weapon. Rapid-fire is difficult and strenuous on the user’s hands, especially for shooters of smaller build or with small hands.

45 ACP

The .45 ACP (Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it was adopted as the standard chambering for Colt’s M1911 pistol.

.45 ACP Cartridge

The standard-issue, military .45 ACP cartridge contains a 230-grain bullet that travels at approximately 830 feet per second (253 m/s) when fired from the government-issue M1911A1 pistol of the time. The cartridge comes in various specialty rounds of varying weights and performance levels as well. The .45 ACP operates at a very low 21,000 copper units of pressure, it has no supersonic crack and is therefore ideal for use with a suppressor.

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