Why did so few militaries use semi automatic rifles as their standard issue infantry weapon?

Question

Semi automatic rifles have been in production since the early 20th century, with the first rifle being tentatively fielded being the French FAM 1917 in small numbers for use in WWI. Despite the utility of the faster-firing guns France ultimately reverted to using the bolt-action Lebel rifle as their primary infantry armament due to the FAM 1917's complexity and cost.

After WWI, the only major army to use the interwar period to equip their soldiers with a semi-automatic rifle was the United States, issuing the M1 Garand as their main infantry weapon.

During WWII war other countries experimented with using semi auto rifles such as Germany creating small batches of the Gewehr 43, and the USSR fielding the SVT-40, and later the SKS. Nearly all countries involved in WWII primarily used bolt-action rifles as their primary infantry armament.

Following the end of WWII few countries equipped themselves semi-automatic rifles, instead opting for the newly available select-fire weapons such as the AK-47, FN FAL, or M16 which are capable of both single fire or fully automatic operation, largely rendering semi-automatic rifles obsolete. In spite of this, the People's Liberation Army of China widely used the SKS, and to a lesser degree, the Vietnamese Army did too.

Apart from the M1 Garand, SKS, and a subset of FN FAL variants (used by Canada) few countries primarily utilized semi automatic rifles.

American troops had wide success in WWII due in part to their rifle. Yet, following the war most countries adopted select-fire weaponry. Did semi-automatic weapons not "get a fair shake" due to swiftly being rendered obsolete after the war? Why did so few countries emulate the success of the M1 Garand and not issue similar guns to their troops or use the interwar period to develop their own semi automatic gun designs?

Answer 1

The USA started development earlier

Generals fight the last war. In the muddy trenches of WWI, the major semi-automatic rifle designs such as the Mondragón Modelo 1908 and the FAM 1917 rifle that you mention proved to be difficult to keep clean enough to operate. Though the FAM 1918 performed well in the Rif Wars, we actually observe FAMs converted from semi-automatic to bolt-action when they were handed over to colonial troops. Given the mood around disarmament at the time, we can assume that the focus for the Great Powers was on colonial policing, rather than preparing for another total war.

As a result, France's next rifle development was also bolt-action, intended to be a cheap gun for colonial troops. The French intended to follow up with the MAS-40 semi-automatic, but the design was only completed in 1949 (at which point it did serve as the standard issue rifle for a decent length of time).

Meanwhile, the USA was working on the Garand as early as 1922.

The USA also had more time to adopt the new design

Even the simple MAS-36 had a very small production run before the war kicked off - only 250,000 were available for the Battle of France in 1940. Even if France had a design like the MAS-40 ready to go on the same day the USA began production of the Garand, it would not have been able to produce it in sufficient numbers. The UK did the same calculus, and when war was imminent it focused on ramping up the tried and tested Lee Enfield rather than try and rush a new design.

It was no cakewalk either for the USA to produce Garands - at first they were only making 10 rifles per day and the army was only fully equipped by 1941. However that was more than good enough because the USA was not at war until that point, and also did not need to replace rifles lost in the field like Britain, France, and the USSR would have.

The USSR only worked out the kinks with the SVT rifles by 1940. By the start of the war, it had not produced sufficient rifles to arm even one third of their forces with it, and many were lost in the first months of the war, requiring the Soviets to fall back to using simpler and cheaper weapons.

War showed the deficiencies of all rifles, including semi-autos

The flaw with the semi-automatic rifle became apparent as soldiers gained experience in the field: they were a weapon designed for long-range marksmanship, which was not how actual battles were fought. The heavy weight and recoil of these guns was a liability with no upside.

The capabilities of rifles such as these were rarely exploited to their fullest, with the chaotic realities of warfare (limited visibility, targets behind concealment or cover, etc.) meaning that most engagements took place at far shorter ranges than anticipated

Nevertheless, the nations fielding these weapons already had the designs and more importantly the bullets, and they were still better than bolt-action rifles, so they kept being made.

Despite the limitations of full-power rifle cartridges, significant logistical and economic investment had been made in these calibres, and these investments, along with idealized military doctrine and the exigencies of an ongoing war, meant that innovation was met with some resistance.

The Germans identified these flaws as early as 1944, leading to the adoption of the StG 44 and a new intermediate sized cartridge. The Soviets were inspired by that design to make their own AK-47. NATO countries took somewhat longer because there was a desire to standardize around one NATO-wide cartridge and gun, and in the meantime existing designs of semi-automatic rifles continued to be produced and used in line with existing doctrine.

Naturally, intermediate cartridges are not automatically (pardon the pun) better than heavy ones. In situations where it makes sense, such as for long-distance marksmanship, semi-automatic and even bolt action rifles are still used today. But from the '50s onwards the assault rifle's trade-offs fit the needs of a typical grunt better, and before the war the bolt action rifle's trade-offs fit the industrial and technological constraints better.

Answer 2

In addition to SPavel's excellent answer...

They were very expensive.

Country	Rifle	Cost (2023 USD)
Germany	Kar98k	~$270
UK	Lee-Enfield No. 4	~$450
USA	M1 Garand	~$1300

With its large manufacturing base, and at the time of adoption a very small army, the US could afford a more expensive rifle.

The US was starting from a relatively clean slate.

Other nations of WW2 had large standing armies with large stocks of bolt-action rifles left over from WW1. The Battle of France, for example, involved almost 7 million troops. Most WW2 armies used modified versions of their WW1 rifles. All the training, tactics, logistics, supply, maintenance, and manufacturing were in place. Moving to a new rifle would require replacing all that with a brand new system, while keeping the old one around during the transition.

In contrast, at the time the M1 was adopted (1936) the US Army in 1936 was anemic; less than 200,000 men and poorly equipped. M1 production was slow and there were many design flaws to be worked out.

When WW2 started the US military had to had to swell up to millions in a few short years. They did not have anything like enough service rifles in inventory for such an expansion. If you're going to make millions of rifles anyway, and you have the industrial power and money to do so, might as well make it the most modern you can get.

Other armies relied on machine guns for squad firepower.

A German infantry squad was centered around a light machine gun, such as the MG 34 and later the MG 42. This made up for the relative lack of firepower of the Kar 98k bolt-action rifles most of the rest of the platoon carried.

The British had the excellent Bren gun for their infantry.

The US never developed a light machine gun for WW2. A soldier could lug around a Browning 30 cal (32 pounds) or a BAR with a 20 round magazine designed for the outdated idea of "walking fire". Both were of (slightly after) WW1 vintage, quite heavy, and inadequate for the light machine gun role.

Instead, by equipping everyone with an self-loading rifle the ordinary rifleman could pour out quite the weight of fire compared to their bolt-action counterparts.

Answer 3

I think SPavel has written a very good answer. However, I think there are two other factors that should be mentioned, and they won't fit well in comments, so I'm adding a supplemental answer.

First, it's worth noting that the US differed from many countries in that it didn't really have a strong commitment to an existing weapon. It entered WWI quite late, and when it did, it was with a mix of M1903 Springfields and M1917 Enfields. The US also had only relatively recently switched from a previous service rifle (the M1892-99 Krags). Conversely, the other WWI combatants who became major WWII combatants generally had more resources invested in their bolt-action rifles (to the extent of my knowledge, of the major WWII combatants, only the US and Japan had adopted their WWI service rifles after 1900; most countries also predominantly used a single rifle as their WWI service rifle, unlike the US's split between the Springfield and Enfield). In other words, the US had less cost sunk into their existing service rifles than most countries, and thus less to lose by moving to a new design. (If standardizing on a single weapon means you already need to rearm half your army, it's not as large of a step to just rearm all of it; and if you're doing that, you might as well use a new design.)

The US also had considerable manufacturing capacity, making it easier to produce a large number of semi-auto rifles (which are comparatively more complex to produce and maintain than bolt-actions) in the time between the wars. (SPavel already noted the difficulty France had in producing the bolt-action MAS-36 in sufficient quantity, but it bears repeating as a point of comparison.) Coupled with the US's relatively late entry into the war (as SPavel also noted), they simply had the luxury of being able to rearm most of their military with the newer, more complicated design, while the required amount of production would have been difficult or impossible to achieve for other countries, especially when early-war combat losses were taken into account.