The 303 British, or 303 Brit, is a cartridge that is pushing 140 years old, first introduced in 1888 and involved in nearly every major conflict in the 20th century it is probably one of the most storied cartridges that can be studied. While the 7.62x54R has the medal for the longest military cartridge to serve as service cartridge (1891 thru to today), the 303 British is older by just a few years, and though not longer formally part of any militaries armory, it is still seen on battlefields in Iraq and Afghanistan.
Despite it’s age, the cartridge has stood the test of time remarkably well, and remains as useful of a cartridge today as it was in 1910. With that said, unless you are into military firearms, or you’ve watched a few episodes of Forgotten Weapons, you probably have not heard much about the 303 Brit. As far as I am aware there are no modern US firearm makers chambering new rifles in the 303 Brit unless it’s a custom rifle. Unless something unexpected occurs, it is likely this cartridge will continue on it’s slow descent into obscurity.
History
The .303 British is a unique cartridge and one of the longer serving military cartridges, serving as the British’s main service cartridge through both World Wars, and seeing use in pretty much every major conflict of the 20th century. However the cartridge today, is different from the cartridge when it was first introduced in the Lee-Metford rifle introduced in 1888.
While it was always intended to be used with the new “Smokeless” powder, the first loads were released utilizing black powder. Thus the development story of the British 303 Cartridge is impart the adoption of smokeless powder by modern military powders. When the first practical smokeless powder was introduce it looked quite different that what we are used to seeing today.
Cordite, was the combination of Nitrocellulose, Nitroglycerine, petroleum jelly and other stabilizers. The mixture was extruded out into long cords which were then cut at a prescribed length. It would have been interesting to see the loading machines that handled and loaded these cartridges, particularly how the powder was handled.
Smokeless powders such as cordite burn at hotter temperatures then black powder does. Which doomed the Lee-Metford rifle. The shallow rifling, designed to lessen fouling from black powder, was burned out by the Cordite. The Lee-Enfield rifle was introduced 1904, solving the primary issues with the Lee-Metford by changing, among other things, the cut of the rifling to a square cut.
The ammunition went through many revisions since it’s first introduction in 1888. What was originally a jacketed 215gr Round Nose bullet, turned into what we’d call a 215gr soft tip round nose bullet. This bullet was designed to expand, much like conventional hunting ammunition is today. The nickname for these bullets were “Dum Dum” which was a reference to the Dum Dum Aresenal located near Calcutta, Inda, where they were manufactured.
The use of expanding ammunition by the British resulted in complaints being made in the Hague Convention of 1899. This resulted in the outlawing of expanding ammunition and changed the design of the 303 Brit yet again. This resulted in the revision to the full metal jacket 215 grain Mark 6 pictured above, and then after seeing the deficiencies when compared to the 8mm Lebel cartridge, lead to the Mark 7 designed pictured below.
It should be noted that the arguments made during the 1899 Hague convention regarding the use of expanding ammunition ended up banning use of such ammunition in future conflicts. However these lead to the development of the Mark 7 round which was tail heavy, as the core was divided with a lighter element in the front, usually aluminum or cellulous, and a lead core in the back. When the bullet hit tissue, the rapid deceleration of the nose coupled with the high velocity of the bullet would cause the heal of the bullet to swing forward and tumble. Causing a devastating wound channel. In addition the bullets tend to break apart where the two cores meet and fragment. In the end it produced similar trauma to expanding bullets of the era and benefited from better ballistics.
It should be noted that the Mark 7 was generally considered the best all around general use rifle bullet for the 303 Brit. While there was the Mark 8, Armor Piercing and Incendiary rounds made they were not in common use. The Mark 8 was optimized for use in the Vickers machine gun and were loaded hotter with a longer boat tailed bullet. However the load would cause wear and tear on the Lee Enfield rifles which were not proofed at the higher pressures of the Mark 8. Surplus ammo that is found bearing the Mark 8 stamp should not be fed into Lee Enfield rifles.
It also should be noted that primers used during this time all contained Mercury Fulminate. Over time the mercury would leach out of the primer and form an amalgam with cartridge brass weakening the case. While this may not have been an issue at the time, it is circinately an issue will military surplus ammunition. In addition these primers are considered corrosive, as they form salts when they burn which coat the inside of the bore attracting water. Many good rifles had their bore pitted beyond repair due to improper cleaning after firing corrosive ammunition.
The 303 Brit was a service cartridge that fought along side the United States 30-06, and against the german 7.9x57mm (8mm Muaser). Of the three cartridges it was the less potent. The 303 has a heavier bullet with a higher BC then the 30-06 but pushes it to a lower muzzle velocity. While it holds on to that energy a bit better, it drops considerable more then the 30-06 or the German 7.9x57mm making longer shots a little harder.
After World War II the British transition their main service cartridge from 303 British to the 7.62x51mm NATO in 1957. The 7.62 NATO a cartridge that is roughly equivalent to the commercial 308 Win (With some minor differences) and sports a much higher service pressure. While some home gunsmiths rechambered their 303 Brits to the 7.62 NATO, it was not a generally recommended practice as the higher service pressure was a bit much for the rear locking action.
The SMLE was properly adapted to fire the 7.62 NATO as the Ishapore 2A/2A1 rifle. Adopted by the Indian army it was the last bolt action rifle manufactured for the purpose of being a front line service rifle. Only about 250,000 units were made, and production ended in 1974.
The 303 Brit remained in service by various rear echelon forces until as late as the early 2000’s. Specifically it was popular with Canadian Rangers only being retired in 2018. The 114 year service life of the rifle and the cartridge it fired is remarkable and only eclipsed by the 7.62x54R.
(As a side note the United States was never a signatory to the Hague Convention of 1899, it has generally adhered to the practice of not using expanding bullets as general service ammunition. Even going so far as having to defend the use of open tip match bullets, such as the Sierra Match King, in certain ammunition declaring that despite the open tip design the bullet itself is not designed nor intended to expand. More information on that here. With that said, I know for a fact that expanding ammunition was sold and used by the United States military in operations conducted in Iraq and Afghanistan and is still likely being used by top tier units today.)
Technical Specs
The 303 Brit is recognized by both SAAMI and CIP and thus published specifications with both organizations. This cartridge is one example where CIP and SAAMI can have two different but comparable standards, in this case the SAAMI MAP is limited at 49,000psi, while the CIP PMax is 52,939psi. The two different standards are likely due more to a difference in service pressure definitions rather then a practical difference in safety. (The CIP pressure is a “No single shot shall exceed,” while the SAAMI method is a “The average pressure of ten rounds shall not exceed”.)
The cartridge head spaces off of the rim, CIP indicates the headspace to be 1.63mm or 0.0641in, SAAMI likewise indicates a Min headspace of 1.63mm (0.0641in) and a Max headspace of 1.80mm or 0.071in.
The max case length length according to SAAMI is 2.222in or 56.44mm, while the min length is 2.202in or 55.93mm. According to CIP the max case length 56.44mm (2.222in), with no min length indicated, however it is generally assumed .51mm or .020in as indicated by the SAAMI drawing. Treat the min cartridge length as a trim to length when trimming brass.
The 303 diameter is based on the bore diameter prior to the rifling cut. Thus the nominal bore diameter is .303in, while the rifling is cut to a diameter of .311 to .314 inches. While .308 or .309 diameter bullet can be shot through a 303 Brit rifle, best accuracy will be achieved using .311 to .312 diameter bullets. With that said it is usually a good idea to slug the bore, as rifling depth varied quite a bit during wartime production, and getting a true measurement of bore diameter is helpful in selecting bullet diameter.
The SMLE rifles were all manufactured with a 1:10in twist barrel. Which is standard for most 30 Calibers and suitable for stabilizing bullets up to 220gr.
It is minute but there are slight differences between the SAAMI and the CIP Min chamber drawings. These changes are small and are unlikely to affect the internal ballistics of the round.
Issues
There are two main issues with this cartridge that shooters should be aware of. The first is related to the nature of rimmed cartridges in general. Cartridges can be improperly loaded into a magazine and cause a condition called rim lock. This is where the rim of the cartridge above is placed so that the rim overlaps on the cartridge below. When the cartridge is stripped from the magazine both cartridges are force forward jamming the rifle.
The second issue is related to the nature of SMLE rifles. Due to the fact the rifle locks in the rear of the bolt the action is “Springy” or has flex. Under firing the case body is held in position due to the pressure however the rear of the case is stretched rearward as the pressure pushes the bolt back. This results in the thinning of the cartridge case just in front of the web of the case. This thinning will eventually result in case head separation which is a less then ideal situation. (I.E Dangerous)
This issue is made worse if the headspace of the rifle is particularly sloppy, which given the age of many of these rifles, is not uncommon. Fixing the headspace will prolong the life of the brass, however it will not resolve the issue completely. 303 Brit brass does not typically have a long service life getting between 5-7 reloads depending on the condition of the rifle. Some people do better some less.
Most if not all military surplus brass is Berdan primed making it difficult to reload. In addition the age of the brass combined with questionable quality usually results in case neck splits which render the cases scrap on the first firing. As previously mentioned the majority of military surplus ammunition is considered corrosive due to the mercury fulminate used in the primers. Higher quality commercial brass may be readily had that is boxer primed, so there’s little incentive to save or reuse the military surplus brass anyway.
In addition to the primers being corrosive, there is a chance that some of the primers may either be dead, or result in a hang fire. A hang fire is a delay between when the primer is struck and when the primer ignites. This delay is usually on the order of milliseconds with a 20 millisecond delay being the threshold where it becomes noticeable to the average shooter. However it can last seconds. When clearing a hang fire it is best to keep the rifle pointed in down range for 30 seconds, and if the round has not discharge, to quickly extract the round.
The Utility of the 303 Brit Today
Given the age of the cartridge you may wonder what the utility of the cartridge is today. Why spend any time at all with the 303 Brit when the 308 Win or 30-06 is by far more common and a superior overall cartridge? It’s a valid question and one that deserves to be address.
The simple answer is that there are still a fair amount of rifles out in the wild that are chambered for the 303 Brit. While new rifles are a scarce find, used rifles, specifically military surplus rifles, are still to be had in pawn shops, in gun stores and sometimes can be found for a bargain. Especially rifles that have been sportified. Rifles that have been cut down, or altered to be handier in the tree stand make for great project rifles, that can teach the owner a thing or two about gunsmithing.
Thanks in part to the Russian 7.62×39 and the 7.62x54R, there remains a decent selection of bullets in .310-.312 diameter. Bullets from 120gr to 220gr can be had with all sorts of profiles and application. I have even played around with bullets weighing 90 and 100gr which were design for the 32 ACP, having a .3125 diameter they load and shoot out of a Lee Enfield with a blistering velocity.
When loading for it, powders such as H322, H335, and other medium speed rifle powders are generally good candidates for this cartridge. With some of the more modern progressively burning powders such as Win StaBALL 6.5 it is possible to exceed the performance of the originally 174gr military load and get around 2600fps which is not bad for a cartridge pushing 140 years old.
The bolt action nature of the Lee Enfield makes it a good candidate for cast loads. Several molds are sold with the intended bullet profile for use in .303 Brit. I find these loads were best with Trail Boss, or a fast burning powder like Unique. I like to call them my mouse fart loads as they are quiet and awfully fun to shoot. They tame the larger service cartridge giving it a recoil similar to that of a 22LR. It can be a hoot to take these light loads and plink with them at 50 or 75 yards. Due to the low pressure, it is easy on the brass.
The cartridge itself is a potent one and has been used to take everything from small game to dangerous game. Generally it is ranked as sufficient to take everything up to mule deer. While I am sure there are people who swear that they have harvested moose and elk, I am recommend going with something like a 30-06 or 308 Win for those larger game animals.
Why it’s a Favorite
This cartridge makes my favorite list for one simple reason, it was the first cartridge I really got to know. You always have a special place in the cockles of your heart for your first “Whatever” it is just human nature, unless it was your first kidney stone….you’ll never have warm feelings about that. Trust me.
I still enjoy loading and shooting it today despite the age of the rifle or the obsolescence of the cartridge it can still take game, produce decent groups, and make for an enjoyable time at the shooting range. I have had more then one good conversation as people wonder what old war horse I’m shooting. The SMLE action is a smooth and quick action, that just feels good to work, even if it isn’t the strongest action out there. The rifle I have has a nice two stage trigger to it, with a decently crisp break. When compared to other rifles of the era, namely the Mosin Nagants, it is a dream.
Sometimes its not about getting the flattest and tightest shooting cartridge out there. Sometimes it is about nostalgia, appreciation for times that have gone by, and the men who live them. There seems to be an uptick in interest in military rifle shooting, whether it be via the Civilian Marksmanship Program, or other private matches, these rifles still make appearances. They still take home medals and they have enduring collectors on all continents.