This is something I've been wanting to write for some time now - it is on the basis of the British re-arming earlier in the 30s and is my understanding of what the British might have ended up with had more time and money been available. This is a follow on from my piece on the Owens SMG I wrote in 2014 and like that earlier piece please feel free to treat this as a resource. 
The Enfield No4 Mk1 SLR and Mk2 SLR AKA the SLEM (Self Loading Enfield Mauser)/FN40 & FN49
A selection of Enfield No4 / SLEM Rifles - From top - 2 x Mk2s then 2 x No4 Mk1s and finally a 'Scopeless' Mk1-T Sniper variant (note the mounting bracket)
When Britain decided to re-arm and modernise its armed forces in the mid 30s it had already long been decided that the .303 round while having served the Empire well was not the main rifle / Machine gun calibre of choice and it was decided that the SMLE and Lewis Machine Gun replacement should both leverage the proprietary 7.92mm Mauser round which enjoyed a much flatter trajectory.
This turned out to be a relatively easy process for the LMG – with Britain choosing a modified version of the Czechoslovakian ZB-26 machine gun which was already designed around the 7.92 mauser round
This weapon would become the ubiquities Bren gun which began initial low rate-production in 1936 and full rate in 4 countries by 1939 and was the principal Section LMG when the British Empire went to war in 1940
Britain also made a licensed copy of the Czechoslovakian ZB53 Machine gun also in 7.92 Mauser...which became the BESA MMG (the only change was the name), used on all British Tanks and armoured cars from the Universal Mk3 Tank onwards
This just left the rifle!
The War Office had rejected various Self loading rifles such as the ZH-29 as being unsuitable during a rifle trial in 1932 and while there was some efforts in leveraging French and US SLR designs being then developed – these efforts met with varying degrees of difficulty and ultimately failed to bear fruit. Of the remaining designs available - none seemed to meet all the criteria of what was wanted.
So in 1935 Fabrique Nationale – who had already been approached regarding their HP34 - Browning Hi – Power pistol – were asked to develop a robust SLR to potentially replace the SMLE.
By 1936 Dieudonne Saive (FNs Chief designer) and his team working with Enfield designers had developed a suitable rifle – using a 10 round box magazine and the same sights and other common features as the SMLE based on an existing design he had patented in 1934 and by 1937 this weapon was adopted as the Enfield No 4 Mk 1 SLR or more commonly the 'SLEM' (Self Loading Enfield Mauser)– and entered initial low rate production in the UK the same year and was eventually mass produced in 5 countries.
There were various versions of the rifle which was built in the UK from 1937 – 1958 (Till 1971 in India) - and in all it's estimated that at least 4.5 million were produced during this time.
The basic model was a gas operated short stroke piston design with a rotating bolt operating from a ‘fixed’ 10 round box magazine that was loaded using 5 round ‘proprietary’ stripper clips. These stripper clips were a direct copy of the ones used for the Mauser K98 rifle then in service with the German Military.
The weapon was rugged, accurate, reliable and well liked by Imperial troops during nearly 30 years of service (till its replacement in the form of another FN designed weapon the FAL Bullpup from 1958) and went on to be described as the 'Right arm of the free world' during the Cold War as it equipped the armies of so many Western backed nations.
The clips were carried in a bandolier that would be looped across the body 'on top' of the 38 and 44 pattern webbing and this bandolier carried 70 rounds in 14 x 5 round stripper clips, and usually 3 would be carried (with 1 or 2 of them in the soldier's pack). Ammunition would be supplied to a given battalion from the parent unit pre-packed in these bandoliers.
In practice however many soldiers did not like the bandoliers (they were prone to catching on pretty much anything all the time) and instead the clips were often stored in one of the two chest pouches (each intended for 2 Bren Gun Magazines) as troops rarely carried 4 Bren Gun mags each in the field.
3 Bandoliers - 210 rounds of ammo - most of the ammo would be used to refill the Sections BREN gun magazines
The No 4 Mk1-T was a basic Mk1 that was chosen for its accuracy and modified with a x3.5 scope fitted to a bracket – while very accurate and a deadly sniper rifle the position of the Scope made use of Stripper clips impossible and the rifle had to be loaded with single rounds. This led to Snipers or sharpshooters equipped with the rifle being provided/equipping themselves, with additional modified box magazines that would enable them to reload when in a hurry by changing magazines. This practice of carrying spare magazines and even using the 20 and even 30 round Bren gun magazines became common among normal riflemen.
An Early No 4 Mk 1T Sniper rifle (Bottom) and a later factory modified No4 MK 2T with 20 round detachable magazine (Top).
In 1942 a simplified select fire version - the No4 Mk2 was produced and this version incorporated as standard a changeable 20 round magazine (although it was expected that troops would still reload in the field using clips). Despite being virtually uncontrollable in full auto the addition of the Full auto feature had been well received by Imperial troops - particularly those fighting in close terrain and many Mk1s had already been field modified.
A late war No 4 Mk 2 - note the 20 round detachable magazine!
Other variants include a jungle carbine version - that was built in Australia in late 1944. This version know as the mk 3 'jungle' Carbine was an attempt to shorten the weapon and lighten it as much as possible in order to make it more suitable for Jungle operations. Unfortunately the designers at Lithgow Smalls Arms Factory went too far in their efforts to lighten it and it was found that the upper receiver had been thinned too much in the area just below the rear sights and this resulted in the weapon very rapidly losing its zero in combat. Also jungle fighters prefered the Owens Imperial Machine Carbine which was available in large numbers by this point in the war - so after less than 15,000 weapons produced - production of the Mk3 was discontinued.
Despite its drawbacks - today the Mk3 remains a very sought after rifle among collectors.
A late war version - the 'Para' or Mk 4 was another 'failed' design - intended to equip paratroopers and tank crews the weapon was modified with a folding stock and 'pistol' grip and usually came equipped with a 30 round Bren gun Magazine. The intention was to provide a weapon that could be used as a 'emergency LMG' for dismounted AFV crew and isolated paratroopers - however the folding stock was not very robust and many soldier complained that the weapons accuracy suffered due to the poor stock.
As it was these drawbacks were thankfully discovered during training and not in the field and the weapon was withdrawn. A very rare variant today with most having been destroyed in the late 40s.
If you do find one today it's very likely to be a Portuguese Para version of the FN49 built under Licence in the 50s - But the Portuguese variety has a much more robust folding stock.
FN also made their own version of the gun - the FN 40 which was effectively a Mk1 and the FN 49 which was effectively a Mk2.
The FN 49 was produced in a variety of Calibres throughout the 50s and early 60s and was sold to over 15 nations and licence made in at least 5.
The Enfield No4 Mk1 SLR and Mk2 SLR AKA the SLEM (Self Loading Enfield Mauser)/FN40 & FN49
A selection of Enfield No4 / SLEM Rifles - From top - 2 x Mk2s then 2 x No4 Mk1s and finally a 'Scopeless' Mk1-T Sniper variant (note the mounting bracket)
When Britain decided to re-arm and modernise its armed forces in the mid 30s it had already long been decided that the .303 round while having served the Empire well was not the main rifle / Machine gun calibre of choice and it was decided that the SMLE and Lewis Machine Gun replacement should both leverage the proprietary 7.92mm Mauser round which enjoyed a much flatter trajectory.
This turned out to be a relatively easy process for the LMG – with Britain choosing a modified version of the Czechoslovakian ZB-26 machine gun which was already designed around the 7.92 mauser round
This weapon would become the ubiquities Bren gun which began initial low rate-production in 1936 and full rate in 4 countries by 1939 and was the principal Section LMG when the British Empire went to war in 1940
Britain also made a licensed copy of the Czechoslovakian ZB53 Machine gun also in 7.92 Mauser...which became the BESA MMG (the only change was the name), used on all British Tanks and armoured cars from the Universal Mk3 Tank onwards
This just left the rifle!
The War Office had rejected various Self loading rifles such as the ZH-29 as being unsuitable during a rifle trial in 1932 and while there was some efforts in leveraging French and US SLR designs being then developed – these efforts met with varying degrees of difficulty and ultimately failed to bear fruit. Of the remaining designs available - none seemed to meet all the criteria of what was wanted.
So in 1935 Fabrique Nationale – who had already been approached regarding their HP34 - Browning Hi – Power pistol – were asked to develop a robust SLR to potentially replace the SMLE.
By 1936 Dieudonne Saive (FNs Chief designer) and his team working with Enfield designers had developed a suitable rifle – using a 10 round box magazine and the same sights and other common features as the SMLE based on an existing design he had patented in 1934 and by 1937 this weapon was adopted as the Enfield No 4 Mk 1 SLR or more commonly the 'SLEM' (Self Loading Enfield Mauser)– and entered initial low rate production in the UK the same year and was eventually mass produced in 5 countries.
There were various versions of the rifle which was built in the UK from 1937 – 1958 (Till 1971 in India) - and in all it's estimated that at least 4.5 million were produced during this time.
The basic model was a gas operated short stroke piston design with a rotating bolt operating from a ‘fixed’ 10 round box magazine that was loaded using 5 round ‘proprietary’ stripper clips. These stripper clips were a direct copy of the ones used for the Mauser K98 rifle then in service with the German Military.
The weapon was rugged, accurate, reliable and well liked by Imperial troops during nearly 30 years of service (till its replacement in the form of another FN designed weapon the FAL Bullpup from 1958) and went on to be described as the 'Right arm of the free world' during the Cold War as it equipped the armies of so many Western backed nations.
The clips were carried in a bandolier that would be looped across the body 'on top' of the 38 and 44 pattern webbing and this bandolier carried 70 rounds in 14 x 5 round stripper clips, and usually 3 would be carried (with 1 or 2 of them in the soldier's pack). Ammunition would be supplied to a given battalion from the parent unit pre-packed in these bandoliers.
In practice however many soldiers did not like the bandoliers (they were prone to catching on pretty much anything all the time) and instead the clips were often stored in one of the two chest pouches (each intended for 2 Bren Gun Magazines) as troops rarely carried 4 Bren Gun mags each in the field.
3 Bandoliers - 210 rounds of ammo - most of the ammo would be used to refill the Sections BREN gun magazines
The No 4 Mk1-T was a basic Mk1 that was chosen for its accuracy and modified with a x3.5 scope fitted to a bracket – while very accurate and a deadly sniper rifle the position of the Scope made use of Stripper clips impossible and the rifle had to be loaded with single rounds. This led to Snipers or sharpshooters equipped with the rifle being provided/equipping themselves, with additional modified box magazines that would enable them to reload when in a hurry by changing magazines. This practice of carrying spare magazines and even using the 20 and even 30 round Bren gun magazines became common among normal riflemen.
An Early No 4 Mk 1T Sniper rifle (Bottom) and a later factory modified No4 MK 2T with 20 round detachable magazine (Top).
In 1942 a simplified select fire version - the No4 Mk2 was produced and this version incorporated as standard a changeable 20 round magazine (although it was expected that troops would still reload in the field using clips). Despite being virtually uncontrollable in full auto the addition of the Full auto feature had been well received by Imperial troops - particularly those fighting in close terrain and many Mk1s had already been field modified.
A late war No 4 Mk 2 - note the 20 round detachable magazine!
Other variants include a jungle carbine version - that was built in Australia in late 1944. This version know as the mk 3 'jungle' Carbine was an attempt to shorten the weapon and lighten it as much as possible in order to make it more suitable for Jungle operations. Unfortunately the designers at Lithgow Smalls Arms Factory went too far in their efforts to lighten it and it was found that the upper receiver had been thinned too much in the area just below the rear sights and this resulted in the weapon very rapidly losing its zero in combat. Also jungle fighters prefered the Owens Imperial Machine Carbine which was available in large numbers by this point in the war - so after less than 15,000 weapons produced - production of the Mk3 was discontinued.
Despite its drawbacks - today the Mk3 remains a very sought after rifle among collectors.
A late war version - the 'Para' or Mk 4 was another 'failed' design - intended to equip paratroopers and tank crews the weapon was modified with a folding stock and 'pistol' grip and usually came equipped with a 30 round Bren gun Magazine. The intention was to provide a weapon that could be used as a 'emergency LMG' for dismounted AFV crew and isolated paratroopers - however the folding stock was not very robust and many soldier complained that the weapons accuracy suffered due to the poor stock.
As it was these drawbacks were thankfully discovered during training and not in the field and the weapon was withdrawn. A very rare variant today with most having been destroyed in the late 40s.
If you do find one today it's very likely to be a Portuguese Para version of the FN49 built under Licence in the 50s - But the Portuguese variety has a much more robust folding stock.
FN also made their own version of the gun - the FN 40 which was effectively a Mk1 and the FN 49 which was effectively a Mk2.
The FN 49 was produced in a variety of Calibres throughout the 50s and early 60s and was sold to over 15 nations and licence made in at least 5.
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