Early self-loaders are rife with examples of problems in the field. A bit of dust or mud could cause the gun to jam or suffer a catastrophic failure. Better machining allowed modern rifles, like the ubiquitous AR and AK platforms, to perform in field conditions. Why did it take decades for gunsmiths to produce something like the American M1, or the AK47? What was the barrier that kept them making expensive and problem-prone self-loaders like the unreliable Cei-Rigotti or the too heavy Winchester '05? How did they overcome this barrier?
There are lots of things keeping down self-loading designs in the first half of the 20th century: technology, manufacturing, money, and war.
One was technology. Today, there’s a broad consensus on how to build a military self-loading rifles. Make it gas-operated rifle with a rotating bolt (M1 Garand) or tilting bolt (FN FAL). But in 1920, the answers weren’t so clear.
There are unique technological challenges to building a self-loading rifle. There’s a lot going on inside any self-loading weapon be it big (like a Maxim machine gun) or small (like a FN Model 1903 pistol). The self-loader has to feed, chamber, lock, fire, extract. That’s doable in a pistol. The forces at work with a round like .32 ACP just aren’t that great. And it’s doable in a machine gun. The mechanisms of a big, hefty gun can handle the power of something like 7.9mm Mauser. This is why pistols and machine guns are the first auto-loading weapons to appear.
A military self-loading rifle is an unhappy medium. It has to handle a powerful cartridge, but still be small and light enough for the average soldier to use.
Now, there are still some successful auto-loading rifles before WWI. The Remington Model 8 and the Winchester Model 1905 come to mind. But these are chambered for smaller sporting cartridges like like .300 Savage or .25SL. Self-loading rifles were clearly feasible. So the challenge facing small arms designers was how to make a military self-loading rifle.
It took decades for designers to work out the best operating principle for a self-loading rifle.
Some designers take the blowback- and/or recoil-operated systems of early 1900s self-loading pistols and submachine guns and just scale them up. For reasons that may seem obvious now, this usually doesn’t work all that well.
Georg Luger tries to take the toggle-locked short recoil action off his famous pistol and scale it up for a full-power rifle cartridge. But the Luger Model 1906 doesn’t work all that well. The Luger system worked fine for 9mm Parabellum, but had trouble dealing with the high extraction pressures of a powerful round like 7.9mm Mauser.
The propellant exploding inside the cartridge would stretch the sides of ductile brass cartridge case and make it "stick" inside the chamber. This lead to a variety of problems. When the extractor claw tried to grab the spent case and pull it out of the chamber, the case might be stuck too firmly, leading to a failure to extract. Other times, the extractor would rip apart the brass case, showering the action with shredded brass and bricking the gun. Other times, the extractor would tug on the stuck case until it suddenly came lose, leading to a very violent extraction and ejection. Just imagine trying to pull out a stuck nail from a piece of wood, only for it to pop free when you least expect it.
Later gun designs solved the chamber pressure and extraction issue with a fluted chamber that vented some of the gas around the case. But this feature didn't appear on Italian machine guns until late in the interwar period. It didn't become widely used until after WWII.
Auto-Ordnance tried to make a rifle that used the Tommy gun’s operating principle (a snake-oil gimmick called the Blish Lock that was effectively just a delayed blowback system). The resulting Thompson Autorifle had even more spectacular issues with extraction. It ejected .30-06 casings so violently that they could maim bystanders. During a 1924 trial, an Autorifle ejected several spent casings with so much force they stuck into a wooden board!
There are plenty of other designers trying (and failing) to come up with their own self-loaders. Around the turn of the century, Paul Mauser loses an eye when one of his experiments self-loaders blows up in his face. The design he comes up with, the Mauser 06/08 Self-loading Rifle, is essentially an embiggened Mauser C06/08 pistol. And it’s rife with the same problems everyone else hit. It needs high tolerance parts and lubricated ammo to reliably cycle and extract.
The need for lubricated ammo kills a lot of the early recoil- and blowback-operated auto-loader designs. The Thompson Autorifle, the 06/08 Mauser, the Pedersen rifle (more on this one later) and many more designs all need lubricated ammo to function well. The lubrication made it easier to slide spent cases out of the chamber. Now, that extra grease, oil, or wax created huge fouling concerns. But without it, the rifles won’t work well. The Japanese made two Pedersen knockoffs for trials, but didn't know about his lubricated ammo and didn't use it. Both were disappointing and malfunction prone.
Other designers try making gas-operated rifles. The French come up with several workable gas-operated rifles, the pre-WWI Meunier rifle (more on this one later) and the mid-WWI RSC 1917. This rifles show promise. The French build and issue nearly 86,000 of them during WWI. But they’re very imperfect guns. They’re long, badly-balanced and prone to fouling. The RSC 1917 got mud in its action easily and its gas system often got gummed up. By the time the follow-on RSC 1918 resolved all these issues, the war was over and French were moving away from its 8mm Lebel cartridge.
Other gas systems had their own issues. Early John Garand designs, the Chinese Liu rifle and the German G41 rifles used the Bang gas trap system. Although had the perfect name for a weapon, the Bang system was flawed. It took (coolish) gas from the muzzle and used it to cycle the action, but that cooler gas created more residue and a major fouling problem.
The vast majority of early auto-loader designs are pretty terrible. Consider US Army Ordnance’s 1929 rifle trials. Most of the rifles are real turkeys, even ones put forwards by major gun manufacturers.
The Colt 1929 rifle fed poorly, its receiver was too long and its barrel was too short (this hurts accuracy), it was too heavy, and it overheated.
The Swiss-made Rheinmetall model 1928 had a Bang-style gas system, and it ended up being too complex (114 parts!), too heavy, too hot, and too unreliable.
The already-mentioned Thompson Autoloading Rifle had been refined for the trials. Its new lubricated ammunition worked fine for a 1,106 rounds, at which point, its bolt cracked under the abuse of the blowback design.
The White gas-operated rifle was light and compact, but that came at the cost of being fragile and prone to parts failures (the White gas system ended up being used on the M14 post-WWII).
Of the many rifles considered, only two designers come out as serious contenders: John Pedersen and John Garand. And even these rifles weren’t perfect, as the 1929 tests and later tests in the 1930s showed.
Pedersen’s delayed-blowback rifle, like most blowback rifles of the era, had to use lubricated ammunition. Pedersen’s solution (use hardened wax that softened after the round was fired) was elegant and far better than using a dust-attracting oiler. But the Army still didn’t like the concept of lubricated ammo. It added expensive and complexity and it raised the specter of fouling. The Pedersen rifle was also complex (99 parts!) and it wasn’t nearly as reliable as a bolt-action rifle.
Garand’s gas-operated design had its issues with reliability. Even after the Garand rifle won the competition, it took over five years of further refinement to get the Garand’s gas system and other features to work satisfactorily.