Understanding Your Rifle
Mechanism
On this page you will find an explanation on how the Mosin M91 works mechanically
Bolt
The M91 features a rotating bolt with two front locking lugs that, untypically, lock horizontally into the receiver. The bolt head is separate and recesses into the body, with a spring-loaded extractor snapping over the cartridge rim only as the bolt closes, making it a push-feed mechanism like the French Lebel.
The bolt handle is attached to a guide protrusion, operating within a split rear receiver bridge.
On the downside of the bolt another guide rib or bar can be found that double acts as a disassembly tool. Its core functionality is the prevention of the bolt rotating while out of battery and stabilising the bolt travel.
The safety is the simplest part of the entire Mosin bolt. The cocking piece, whose rear end also acts as a gas shield as the Mosin lacks any other gas mitigating features, can simply be pulled back, turnt left and rested onto a milled out section of the left receiver wall.
Additionally, bolt removal is achieved simply by pulling the bolt fully rearward and pressing the trigger.
Despite Russian arms having a reputation of simplicity, the Mosin presents itself as quite overengineered with the bolt consisting of many separate components and an array of complicated solutions that, while providing usually flawless operation, make it prone to a less-than-ideal experience when working the action due to a lot play being inherent to the bolt.
Magazine
The M91's magazine, Nagant's contribution to the rifle, features a protruding single stack magazine fixed to the action.
Loading happens through proprietary chargers for five rounds each. The charger guides are milled into the split receiver bridge at the back of the receiver.
Internally the magazine is very simple, with two arms raising the follower, supported by a spring. Despite the core being a Nagant design, Mosin influenced the part in so far that Nagant's initial design did not have a dedicated follower.
Additionally the ability to easily remove the magazine floor together with the follower assembly is a solution Mosin came up with.
As the M91 is a push feed rifle, there is an inherent chance of double-feeding happening, meaning a cartridge being chambered partially without being fired and a second cartridge being fed into its back, the bullet tip potentially setting off the primer of the previous cartridge, leading to detonation out of battery.
In order to prevent this, the M91 utilises an “interrupter” mechanism within the receiver, a small part that prevents extra rounds from slipping into the path of the bolt before it has been fully closed on the previous cartridge and thus allowed for extraction of it.
Nagant, whose name would become attached to Mosin's rifle in the West, initially was not going to be paid for his magazine as per the definitions of the ministry's trials which did not plan on a payment for only parts of a presented rifle being adopted - in this case the magazine.
However, with the Russian Empire outsourcing initial production to France, where Nagant's magazine had been patented, the Russians had no choice but to pay for the use of it.
Bayonet
Despite being state-of-the-art in a variety of fields, the Russians stuck with an almost archaic way of attaching the bayonet.
Unlike contemporary rifles, who utilised a variety of lug designs to lock onto corresponding slots on their bayonets' pommels and being held there, the M91 bayonet is a socket attached ones with a screw-locked ring.
This means that the bayonet can not be disattached without tools, as it was intended, with the rifles being sighted with the bayonet attached.
The later M91/30 model in use with the Soviet Red Army would rectify this partially by adding a push button release for the locking collar.
