The practice of projecting grenades with rifle-mounted launchers was first widely used during World War I and continues to the present, with the term "rifle grenade" now encompassing many different types of payloads including high explosive, fragmentation, and anti-tank warheads as well as concussion, smoke, incendiary, and flare missiles.
Rifle grenades have largely been supplanted in the infantry fire support role by a combination of grenade launchers (typically affixed to rifles) and disposable anti-armor rockets.
Adaptation of grenades for use in rifles began around 1904. The first experiments are credited to a Japanese Colonel Amazawa, who experimented with rifle fired grenades during the Battle of Port Arthur in the Russo-Japanese War, and the idea was further used by the Spanish, though the French were the first to put it to widespread use during the trench warfare of World War I.
In 1907, Martin Hale developed the rod grenade. "A simple rod was attached to a specialized grenade, inserted into the barrel of a standard service rifle and launched using a blank cartridge." The British did not immediately adopt the idea and entered World War I without any rifle grenades. However, as soon as the trench warfare started, there was a sudden need for rifle grenades. The British government purchased a rodded variant of the No 2 grenade as a temporary solution.
By 1915, Hales had developed the No 3, which is commonly known as the Hales rifle grenade. The Hales grenade was improved throughout World War I to make it more reliable and easier to manufacture. However, production of the grenade was slow. In order to speed rod grenades to the front, the British also made rodded versions of the Mills bomb.
Although a simple approach, launching a rod grenade "...placed an extreme amount of stress on the rifle barrel and the rifle itself, resulting in the need to dedicate specific rifles to the grenade launching role, as they quickly became useless as an accurate firearm. This led to the search for an alternative and resulted in the reappearance of the cup launcher during the latter years of World War I". After World War I, the rod-type rifle grenade was declared obsolete and the remaining Hales were replaced with gas check equipped Mills Bombs shot from a rifle via a cup launcher.
The French grenade, named the V-B grenade after its inventors, Viven and Bessires, was fired from the standard service rifle with the use of a special adapter and a standard cartridge, providing an effective range of around 175 to 200 yards, while the effective radius of the bursting grenade was 75 yards. The grenade had a hollow through the middle, allowing the bullet to pass through, while the muzzle blast was captured by the launching device and used to propel the grenade. The bullet, after passing through the body of the grenade, struck a small plate that ignited the primer. This then lit the fuse in the grenade, providing an eight-second delay before detonation. It could be fired from the shoulder, but due to the heavy recoil and poor balance of the rifle fitted with the grenade, it was more common to fire it with the butt of the rifle resting on the ground, and either held at an appropriate angle, or resting on a tripod. The rifle grenade was useful in offense, particularly in attacking sandbag fortified machine gun nests, as well as in defense. Eight men armed with rifle grenades could fire 150 shots in a minute, providing a heavy barrage to break up an attacker's lines.
Upon entering World War I, the United States attempted to adopt the V-B grenade, but this was not very successful. The difference between the French and American service cartridges (8 mm vs. 7.62 mm) meant that the grenade had to be re-designed with a smaller hole, but even this was not sufficient to ensure reliable functioning, due to differences in bullet design. The American bullet would often break apart in the grenade, and this led to the V-B derived grenade design being scrapped in May 1918.
The next United States attempt at a rifle grenade was to return to and develop an improved rod-grenade. The Babbitt grenade, developed by Colonel E. B. Babbitt of the U. S. Ordnance Department, used a long stem projecting from the rear of the grenade, which was slipped into the barrel of the Springfield 1903 rifle, and propelled with a special blank cartridge. The stem was calibrated with a number of grooves and a split ring, which allowed the user to set the grenade to slide a certain distance into the muzzle of the rifle. With the stem was inserted only part way, the chamber pressure upon firing was reduced, propelling the grenade a shorter distance. When fired at a 45-degree angle, ranges from 50 to 300 yards were possible; with the rifle angled at 80 degrees, ranges as short at 15 yards were possible. In addition to providing the force to propel the grenade, the gases from firing were directed through a hollow in the stem, and provided force to arm the grenade. Once armed, the grenade had a heavy plunger that would detonate the grenade upon impact.