Inspection after incision and analysis of the gas release system

Inspection after sectioning and analysis of the gas venting system

Inspection after sectioning of the barrel breech and bolt group
Following the initial inspection and disassembly of the firearm, a section cut was made through the barrel breech, receiver, and stock to assess internal deformations and mechanisms of catastrophic failure.
Based on the results of the sectioning, it was determinedthat no manufacturing defects, material inhomogeneities, or pre-existing cracks were found.

Direction and character of the gas flow
During the incident, a transverse case rupture occurred. The primer remained intact and the flash hole played no part in pressure relief.

The primary propellant gas flow:
– originated within the chamber volume;
– exited through the transverse case rupture zone;
– then traveled along the outer surface of the bolt head and bolt body toward the rear of the receiver.
A continuous brass film on the outer surface of the bolt body and bolt group components confirms this gas flow path.

Function of the standard gas venting systems

In the incident under review:
– the primer was not pierced;
– the flash hole played no part in gas venting;
– the primary gas flow was directed not into the interior of the bolt, but into the cavity between the bolt body and the receiver.
The standard gas venting systems were neither blocked nor failed; however, they were physically unable to handle the primary volume of gas at such pressure levels.

Bolt body failure
The failure of the bolt body served a sacrificial function:
– a portion of the energy was absorbed by the failure;
– the load on the bolt head locking lugs and receiver locking lugs was reduced;
– rearward ejection of the bolt was prevented;
– the risk of serious injury to the shooter was minimized.

Conclusion on gas venting
The absence of gas venting ports in the bolt body is not a design deficiency and is not related to the cause of the incident.

In this scenario:
– gases did not enter the interior of the bolt body;
– the primary flow traveled along the outside of the bolt head and bolt body;
– the presence of ports in the bolt body would not have affected the progression of the incident.

The design performed correctly for an extreme scenario, and the failure of the bolt group occurred in a zone that effectively absorbed the incident energy.