Download Yamaha K-31 Technical data

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If the bolt cannot be opened:
-Remove the magazine,
-Place the cocking piece sear between the safety slot and the firing slot in the bolt plug,
-Pull the bolt back by the handle with blows of the palm of the hand if required,
-Remove the bolt, disassemble and inspect all of the parts (especially the cam follower
-If no defect or damage is found reassemble and reload per step b,
d) If the bolt cannot be opened per step c:
-Safe the weapon and contact the specialist (gunsmith).
18 Loading malfunctions are caused the majority of the time by cartridges that are poorly placed in
the magazine or and foreign object in the system.
If the malfunction is caused by a case that is lodged in the chamber, extract it by closing and
opening the bolt several times; the bolt should be open by small taps to the handle of the cam
follower plate. If the case still remains in the chamber, use a cleaning rod to remove it. The cause
of this malfunction could be due to a worn or broken extractor claw or because the chamber has
become so dirty that the case remains stuck in the chamber.
19 Misfires can be caused when the bolt is not closed all the way, the firing channel is dirty or full of
grease or the point of the firing pin is broken. If these causes have been eliminated and the rifle
still does not discharge and the cartridge will not fire in another rifle, then the cartridge must be
considered a “misfire”.
20 Only the gunsmith is authorized to:
-Repair trigger mechanism malfunctions (for example, insufficient sear engagement)
-Remove foreign object, such as cleaning rods or parts of cleaning cord that are jammed in the
All needed repairs to be performed while on duty, can only be performed by troop gunsmiths or
arsenal gunsmiths; all repairs that may be required while off duty, can only be performed by
gunsmiths authorized to repair service (military) weapons.
21 If serious damage or malfunctions occur to the weapon or ammunition, apart from those caused by
weapon discharge, and if this damage will cause or could cause an accident, carefully gather all of
the damaged parts, as well as the cartridges, and set them aside without any modification. Advise
Military Technical Services in Bern by telephone at (031/61 76 26) or by telegraph so that the
damage may be studied in place and without delay, to determine the cause.