Delta L problem
Encyclopedia
The delta L problem is a condition that occurs regarding certain firearms chambers and their practical incompatibility with ammunition
made for the corresponding chambering.
The ΔL refers to a Commission Internationale Permanente (C.I.P.) geometric dimensioning and tolerancing
definition for firearms cartridge cases which are longer than the chamber they have to fit in.
If the chamber in a C.I.P. conform firearm
(a firearm with chamber dimensions specified by the Commission Internationale Permanente) is shorter than a non-C.I.P. conform maximum sized cartridge
(a cartridge with external dimensions larger than specified by the Commission Internationale Permanente), use of that ammunition in the firearm may lead to chambering and/or feeding problems in the shoulder area or other headspace issues.
There is normally no cause for alarm regarding any cartridge designated as a ΔL problem cartridge, as the ΔL problem does not create a dangerous condition in the firearm in the rare event that ΔL problems are actually present.
Firearms users that have to rely on their arm under adverse conditions, such as big five and other dangerous game
hunters, obviously have to check the correct functioning of the firearm and ammunition they intend to use before exposing themselves to potential dangerous situations.
.30-06 Springfield maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).
Junction cone dimensions
alpha (α) = Angle of junction cone (Americans would define the shoulder angle as alpha/2)
S = Length of the peak of the junction cone
r1 min = Radius of junction at the extremities of diameter P2
r2 = Radius of junction between junction cone and collar
The diameters of the cartridge are, logically, smaller than the appropriate diameters of the chamber. But the corresponding lengths "L1" and "L2" are larger. This condition results from the fact that the length on the junction cone becomes larger, if the diameter becomes smaller. With most European cartridges the dimension "S" is always identical. On the other hand many American cartridge designs exhibit an oversize designated as delta L (ΔL). This leads to the situation that a cartridge, which is manufactured at the permissible upper tolerance limit can not be loaded into a chamber that was manufactured, at the likewise permissible, lower tolerance limit. Because cartridges are dimensionally often manufactured in the lower dimensional tolerance limits and chambers tend to be dimensionally manufactured in the higher dimensional tolerance limits these problems are often avoided with (semi) automatic and repeating arms. The locking mechanism normally compensates a light oversize of 0.02 mm – 0.03 mm without any problems.
On the other hand this oversize is a major problem with break action and combination gun
s, which are less common in the United States than in Europe, because correct cartridges cannot be loaded into correct weapons in the event ΔL was not considered during manufacturing. Break barrel arms will not simply close when the cartridges and chamber dimensions are not in concert. For this reason the chambers of break barrel arms are generally manufactured with reamer
s that take ΔL into account.
Generally bolt-action
and break barrel hunting rifles in C.I.P. regulated countries are not cut to the minimum C.I.P. chamber dimensions so this problem is mostly theoretical. The arms manufacturer SIG SAUER brands Blaser
and Mauser
are however known for hammer forging tight (but still C.I.P. conform) chambers in their Blaser R93 straight pull bolt-action and Mauser
M03 bolt-action switch barrel rifles and some rifle owners reported ΔL problems with those rifles. These problems can also occur with other European made rifle brands.
have assigned different standards for the same cartridges. This leads to officially sanctioned conflicting differences between European and American ammunition dimensions and chamber dimensions. Since C.I.P. and SAAMI do not rule nor control civilian ammunition standards worldwide other causes for conflicting standards leading to ΔL issues are also possible.
cartridge family with ≈ 0.15 mm (0.0059 in) theoretical chamber length shortage to be the most prominent ΔL problems candidate.
The value of ΔL must be taken from the relevant calibres in the C.I.P. Tables.
The headspace defined by:
Depth of rim recess
Chamber cone
End of chamber
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
made for the corresponding chambering.
The ΔL refers to a Commission Internationale Permanente (C.I.P.) geometric dimensioning and tolerancing
Geometric dimensioning and tolerancing
Geometric dimensioning and tolerancing is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models for explicitly describing nominal geometry and its allowable variation...
definition for firearms cartridge cases which are longer than the chamber they have to fit in.
If the chamber in a C.I.P. conform firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
(a firearm with chamber dimensions specified by the Commission Internationale Permanente) is shorter than a non-C.I.P. conform maximum sized cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
(a cartridge with external dimensions larger than specified by the Commission Internationale Permanente), use of that ammunition in the firearm may lead to chambering and/or feeding problems in the shoulder area or other headspace issues.
There is normally no cause for alarm regarding any cartridge designated as a ΔL problem cartridge, as the ΔL problem does not create a dangerous condition in the firearm in the rare event that ΔL problems are actually present.
Firearms users that have to rely on their arm under adverse conditions, such as big five and other dangerous game
Big Five game
The phrase Big Five game was coined by white hunters and refers to the five most difficult animals in Africa to hunt on foot. The term is still used in most tourist and wildlife guides that discuss African wildlife safaris. The collection consists of the lion, African elephant, cape buffalo,...
hunters, obviously have to check the correct functioning of the firearm and ammunition they intend to use before exposing themselves to potential dangerous situations.
Delta L (ΔL) problem
The length specification "S" is a basic dimension (or a datum reference) for the computation of the dimensions of firearms cartridges and chambers. It designates the distance between the breech contact surface and the apex of the junction cone. When the length values for the peak of the junction cone measure of the cartridge and the chamber are compared it becomes clear that these values do not always agree. A precondition for such a comparison is that the shoulder angles are identical, since otherwise shifts will occur, which are not recognizable at first glance..30-06 Springfield maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).
Junction cone dimensions
alpha (α) = Angle of junction cone (Americans would define the shoulder angle as alpha/2)
S = Length of the peak of the junction cone
r1 min = Radius of junction at the extremities of diameter P2
r2 = Radius of junction between junction cone and collar
The diameters of the cartridge are, logically, smaller than the appropriate diameters of the chamber. But the corresponding lengths "L1" and "L2" are larger. This condition results from the fact that the length on the junction cone becomes larger, if the diameter becomes smaller. With most European cartridges the dimension "S" is always identical. On the other hand many American cartridge designs exhibit an oversize designated as delta L (ΔL). This leads to the situation that a cartridge, which is manufactured at the permissible upper tolerance limit can not be loaded into a chamber that was manufactured, at the likewise permissible, lower tolerance limit. Because cartridges are dimensionally often manufactured in the lower dimensional tolerance limits and chambers tend to be dimensionally manufactured in the higher dimensional tolerance limits these problems are often avoided with (semi) automatic and repeating arms. The locking mechanism normally compensates a light oversize of 0.02 mm – 0.03 mm without any problems.
On the other hand this oversize is a major problem with break action and combination gun
Combination gun
A combination gun is a break-action hunting firearm that comprises at least two barrels, a rifle barrel and a shotgun barrel, often but not always in an over and under configuration; side-by-side variations are known as cape guns. A ' refers to a combination gun that has three barrels...
s, which are less common in the United States than in Europe, because correct cartridges cannot be loaded into correct weapons in the event ΔL was not considered during manufacturing. Break barrel arms will not simply close when the cartridges and chamber dimensions are not in concert. For this reason the chambers of break barrel arms are generally manufactured with reamer
Reamer
A reamer is a metalworking tool used to create an accurate sized hole. The process is called reaming. They may be used as a hand tool or in a machine tool, such as a milling machine or drill press.-Construction:...
s that take ΔL into account.
Generally bolt-action
Bolt-action
Bolt action is a type of firearm action in which the weapon's bolt is operated manually by the opening and closing of the breech with a small handle, most commonly placed on the right-hand side of the weapon...
and break barrel hunting rifles in C.I.P. regulated countries are not cut to the minimum C.I.P. chamber dimensions so this problem is mostly theoretical. The arms manufacturer SIG SAUER brands Blaser
Blaser
Blaser Jagdwaffen GmbH is a firearms manufacturer mostly of hunting rifles in Germany.It was founded in 1957 by Horst Blaser, developing the Drilling Blaser Diplomat....
and Mauser
Mauser
Mauser was a German arms manufacturer of a line of bolt-action rifles and pistols from the 1870s to 1995. Mauser designs were built for the German armed forces...
are however known for hammer forging tight (but still C.I.P. conform) chambers in their Blaser R93 straight pull bolt-action and Mauser
Mauser
Mauser was a German arms manufacturer of a line of bolt-action rifles and pistols from the 1870s to 1995. Mauser designs were built for the German armed forces...
M03 bolt-action switch barrel rifles and some rifle owners reported ΔL problems with those rifles. These problems can also occur with other European made rifle brands.
Conflicting industry standards
The main cause for the ΔL is that the two main civilian ammunition and firearms industry standards organizations C.I.P. and SAAMISporting Arms and Ammunition Manufacturers' Institute
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...
have assigned different standards for the same cartridges. This leads to officially sanctioned conflicting differences between European and American ammunition dimensions and chamber dimensions. Since C.I.P. and SAAMI do not rule nor control civilian ammunition standards worldwide other causes for conflicting standards leading to ΔL issues are also possible.
Delta L (ΔL) cartridges list
The C.I.P. published a ΔL cartridge and theoretical C.I.P. minimum chamber length shortage dimensions list. The value of ΔL must however be taken from the relevant cartridge data information in the C.I.P. Tables. Most cartridges on the list are of American origin, and many are only chambered in commercial firearms manufactured by American companies using SAAMI specifications. The table shows the popular .30-06 Springfield.30-06 Springfield
The .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...
cartridge family with ≈ 0.15 mm (0.0059 in) theoretical chamber length shortage to be the most prominent ΔL problems candidate.
List of cartridges for which C.I.P. lists ΔL and the amount in millimeters (mm)
Calibre (C.I.P. nomenclature) ΔL (mm)- .17 Libra 0.25
- .17 Remington.17 RemingtonThe .17 Remington was introduced in 1971 by Remington Arms Company for their model 700 rifles.It is based on the .223 Remington, necked down to .172in , with the shoulder moved back. It was designed exclusively as a varmint round, though it is suitable for smaller predators. There are those such as...
0.07 - .220 Swift.220 SwiftThe .220 Swift is a semi-rimmed rifle cartridge developed by Winchester and introduced in 1935. It was the first factory loaded rifle cartridge with a muzzle velocity of over...
0.10 - .221 Remington Fireball.221 Remington FireballThe .221 Remington Fireball was created by Remington Arms Company in 1963 for use in their single-shot bolt-action pistol called the XP-100. This was a special round designed for an experimental pistol, and has the highest velocity of any commercial pistol cartridge.-History:In the early 1960s...
0.09 - .222 Remington.222 RemingtonThe .222 Remington aka the Triple Deuce/Triple Two/Treble Two is a centerfire rifle cartridge introduced in 1950, and was the first commercial rimless .22 cartridge made in the United States...
0.07 - .222 Remington Magnum.222 Remington MagnumThe .222 Remington Magnum was a short-lived commercially produced cartridge derived from the .222 Remington. Originally developed for a US prototype military rifle in 1958, the cartridge was not adopted by the military, but was introduced commercially in sporting rifles.-Development:The .222 Rem....
0.09 - .22-250 Remington.22-250 RemingtonThe .22-250 Remington is a very high-velocity , short action, .22 caliber rifle cartridge primarily used for varmint hunting and small game hunting, though it finds occasional use on deer. This cartridge is also sometimes known as the 22 Varminter or the 22 Wotkyns Original Swift...
0.08 - .223 Remington.223 RemingtonThe .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...
0.07 - .223 Winchester Super Short Magnum.223 WSSMThe .223 WSSM is a .224 caliber rifle cartridge created by Winchester and Browning based on a shortened version of the Winchester Short Magnum case.- History :...
0.08 - .243 Winchester.243 WinchesterThe .243 Winchester is a popular sporting rifle cartridge. Initially designed as a varmint round, it is now more frequently used on medium to large game such as whitetail deer, mule deer, pronghorn, wild hogs, and even black bear and caribou...
0.10 - .243 Winchester Super Short Magnum.243 WSSMThe 243 Winchester Super Short Magnum or 243 WSSM is a rifle cartridge introduced in 2003. It uses a .300 WSM case shortened and necked down to accept a .243in/6mm diameter bullet, and is a high velocity round based on ballistics design philosophies that are intended to produce a high level of...
0.08 - .25-06 Remington.25-06 RemingtonThe .25-06 Remington had been a wildcat cartridge for half a century before being standardized by Remington in 1969. It is based on the .30-06 Springfield cartridge necked-down to .257 inch caliber with no other changes...
0.15 - .257 Roberts.257 RobertsThe .257 Roberts a medium powered .25 caliber cartridge known affectionately as the Bob. It has been described as the best compromise between the low recoil and flat trajectory of smaller calibers such as the .22 and 6mm, and the strong energy but not the strong recoil of larger popular hunting...
0.15 - .260 Remington.260 RemingtonThe .260 Remington 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...
0.10 - .270 Winchester.270 WinchesterThe .270 Winchester was developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54. The cartridge is based upon the .30-06 Springfield...
0.15 - .270 Winchester Short Magnum.270 Winchester Short MagnumThe 270 Winchester Short Magnum or 270 WSM is a short, unbelted, magnum Cartridge created by necking down the .300 Winchester Short Magnum and fitting it with a .277 caliber bullet...
0.10 - .280 Remington.280 RemingtonThe .280 Remington, also known as the 7 mm Express Remington, was introduced in 1957 for the Remington model 740, 760, 721 and 725 rifles. The .280 is based on the .30-06 Springfield necked down to accept 7 mm bullets, with the neck moved forward .050in...
0.14 - .284 Winchester.284 WinchesterThe .284 Winchester is an example of a commercially rather unsuccessful cartridge that has enjoyed a resurgence in interest due to interest from long-range competitive shooters...
0.10 - .300 Lapua Magnum.300 Lapua MagnumThe .300 Lapua Magnum is a specialized rimless bottlenecked centerfire cartridge developed for long-range rifles. The commercially successful .338 Lapua Magnum cartridge has functioned as the parent case for the .300 Lapua Magnum, which is essentially a necked-down version of the .338 Lapua Magnum...
0.07 - .300 Remington Ultra Magnum.300 Remington Ultra MagnumThe .300 Remington Ultra Magnum, also known as the .300 Ultra Mag or .300 RUM is a 7.62 mm caliber rifle cartridge , 7.62x72mm, or .30 caliber rifle cartridge introduced by Remington Arms in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums...
0.11 - .300 Winchester Short Magnum.300 WSM.300 Winchester Short Magnum is a thirty caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2001 by Winchester. The cartridge overall length is 72.64mm, cartridge case is 53.34mm in length and the bullet diameter is .308 in , which is common to all U.S. .30...
0.10 - .30-06 Court Cartry 0.16
- .30-06 Springfield.30-06 SpringfieldThe .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...
0.16 - .308 EH 0.10
- .308 Winchester.308 WinchesterThe .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...
0.10 - .325 Winchester Short Magnum.325 WSM.325 Winchester Short Magnum is an 8 mm caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2005 by Winchester...
0.10 - .338 Lapua Magnum 0.05
- .338 Remington Ultra Magnum.338 Remington Ultra MagnumThe .338 Remington Ultra Magnum is a .338 caliber rifle cartridge introduced by Remington Arms in 2002. It is a beltless, rebated rim cartridge based on the .300 Remington Ultra Magnum case shortened .090" loaded with a .338 caliber bullet...
0.12 - .35 Remington.35 RemingtonThe .35 Remington is the only remaining cartridge from Remington's lineup of medium power rimless cartridges still in commercial production. Introduced in 1906, it was originally chambered for the Remington Model 8 semi-automatic rifle in 1908.-History:...
0.13 - .35 Whelen.35 WhelenThe .35 Whelen is a powerful medium-bore rifle cartridge that does not require a magnum action or a magnum bolt-face. The parent of this cartridge is the .30-06 Springfield, which is necked-up to accept a bullet diameter of...
0.15 - .358 Winchester.358 WinchesterThe .358 Winchester is a .35 caliber rifle cartridge based on a necked up .308 Winchester created by Winchester in 1955. The cartridge is also known in Europe as the 8.8x51mm. -History:...
0.10 - .375 Remington Ultra Magnum.375 Remington Ultra MagnumThe .375 Remington Ultra Magnum, also known as the .375 RUM is a .375 rifle cartridge introduced by Remington Arms in 2002. It is a beltless, rebated rim cartridge created by necking up the .300 Remington Ultra Magnum case to .375 caliber with no other changes. The .375 Remington Ultra Magnum is...
0.10 - .50 Browning 0.28
- 5.45 x 18 0.19
- 5.45 x 39 0.13
- 5.6 x 39 0.06
- 5.7 x 28 0.08
- 6 mm BR Norma 0.07
- 6 mm BR Remington 0.07
- 6 mm Remington6 mm RemingtonThe 6mm Remington was introduced by Remington Arms Company in 1955 as the .244 Remington. It is based on necking down the .257 Roberts. Originally intended as a Varmint and predator cartridge, the .244 was never factory loaded with bullets over 90 grains. Rifles marked .244 Remington have a 1 in ...
(.244 Rem) 0.10 - 6 x 47 SM 0.08
- 6 x 62 Freres 0.12
- 6.5 x 55 SE 0.09
- 6.5 x 64 Brenneke 0.19
- 7 mm BR Remington 0.08
- 7 mm Express Remington 0.14
- 7 mm Remington Ultra Magnum7 mm Remington Ultra MagnumThe 7mm Remington Ultra Magnum or 7mm RUM is a 7mm rifle cartridge introduced by Remington Arms in 2001.-Overview:The 7mm RUM was created using the .404 Jeffery case which was also used to develop the .375 RUM .300 RUM, and .338 RUM...
0.10 - 7 mm Winchester Short Magnum7 mm WSMThe 7mm Winchester Short Magnum is a centrefire cartridge developed in partnership with Browning Arms Company and Winchester ammunition, making its debut and introduced to the shooting public in 2001.-Specifications:...
0.10 - 7 mm-08 Remington7 mm-08 RemingtonThe 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 bullets with a small increase in case length...
0.10 - 7 x 33 SAKO 0.09
- 7.21 Firebird 0.05
- 7.62 x 39 0.21
- 7.65 x 53 Argentine 0.18
- 7.82 Warbird 0.05
The value of ΔL must be taken from the relevant calibres in the C.I.P. Tables.
Firearm cartridges with otherwise problematic headspace
There are also some firearm calibers with problematic headspace listed by C.I.P.The headspace defined by:
Depth of rim recess
- .303 British.303 British.303 British, or 7.7x56mmR, is a .311 inch calibre rifle and machine gun cartridge first developed in Britain as a blackpowder round put into service in December 1888 for the Lee-Metford rifle, later adapted to use smokeless powders...
- .38 Sp AMU
- 6.35 Browning
- 7.65 Browning
- 9 mm Browning long
Chamber cone
- .220 Swift.220 SwiftThe .220 Swift is a semi-rimmed rifle cartridge developed by Winchester and introduced in 1935. It was the first factory loaded rifle cartridge with a muzzle velocity of over...
- .225 Winchester.225 WinchesterThe .225 Winchester cartridge was created in 1964 by the Winchester Repeating Arms Company. Based upon the .219 Donaldson Wasp cartridge, it is a semi-rimmed cartridge, which was an oddity for a cartridge introduced at the time...
- .307 Winchester.307 WinchesterThe 307 Winchester cartridge was introduced by Winchester in 1982 to meet the demand of .300 Savage performance in a lever-action rifle equipped with a tubular magazine...
- .356 Winchester.356 WinchesterThe .356 Winchester is a semi-rimmed, bottle necked, centerfire rifle cartridge which was intended for use in lever action rifles. It was developed concurrently with the .307 Winchester which acted as the parent cartridge...
- .357 Auto
- .38 Super Auto
- 6.5 x 51 R Arisaka
- 7.62 x 54 R
- 9 x 22 MJR
End of chamber
- .357 SIG.357 SIGThe .357 SIG pistol cartridge is the product of Swiss-German firearms manufacturer SIG-Sauer, in cooperation with the American ammunition manufacturer Federal Cartridge. While it is based on a .40 S&W case necked down to accept bullets, the .357 SIG brass is slightly longer...
- 9 x 25 Super Auto G9x25mm Super Auto GThe 9x25mm Super Auto G, officially known as the 9 x 25 Super Auto G by C.I.P. and unofficially also known as the 9 x 25 Super Auto Grillmeyer, is an Austrian pistol cartridge....
External links
- C.I.P. decisions, texts and tables. (free current C.I.P. CD-ROM version download (ZIP and RAR format)