Rifle

The difficulty with these former weapons was their unwieldiness.  While the infantry moved forward during a raid or attack the machine gun invariably proved impractical, both in terms of managing the machine gun itself but as much for the weight of the rounds of ammunition required to keep it serviceable.

As for the mortar, the fact that it was a one-shot weapon reduced its effectiveness.  Grenades certainly had their role during a raid, but carrying buckets of supplies quickly proved tiring, and supplies generally ran out quite quickly.

Which left the pistol and the rifle, both key weapons on the battlefield, although the former was used less as an offensive weapon than the rifle, and were generally issued to officers rather than regular soldiery. 

Although magazine design was clearly a factor in determining rifle performance, a greater impact was dependent upon the training and skill of the rifle operator himself.  Much has been made of the 15 rounds per minute achieved at Mons by riflemen of the British Expeditionary Force.  However these were highly trained soldiers of what was then (August 1914) a professional army.

The flood of entrants to the New Armies - of all nations - could not hope to achieve such a sustained accurate rate of fire.  The norm was perhaps eight to twelve rounds per minute.

In terms of range, the average during the war was around 1,400 metres, although accuracy could only be guaranteed at around 600 metres.

However, despite the lack of accurate fire at range by the newer recruits and conscripts, the rifle was a deadly weapon when used in a defensive formation with infantrymen protected within a trench.  When matched with machine guns, a company of riflemen could unleash a devastating barrage of bullets that could knock down any group of attackers within seconds.  Both the rifle and the machine gun in a trench warfare environment gave the defense a huge advantage over any attacking force.