MIL-DTL-13931J
a. Any portion of the plated surface with two or more visible cavities spaced not more than 0.5
inch apart (between nearest edges of nearest cavities) in a direction parallel to the bore axis and
not more than 0.1 inch apart in the transverse direction.
b. The area of any single cavity that is separated from all other cavities by greater distances than the
limits stated in a. and whose maximum dimension exceeds 0.1 inch. (A similarly isolated cavity
0.1 inch or less in maximum dimension shall not constitute a chipped area).
6.3.4 Bend. Bend in a machined tube is the deflection, excluding droop, from a theoretical straight line
extending between the bore centers at the origin of rifling or forcing cone and at the muzzle end.
6.3.5 Staking. Staking consists of deforming the metal of assembled parts in such a way as to prevent
loosening under operating conditions. It is usually applied to cylindrical parts at one or more points
around the periphery by a sharp tool (prick punch) that forces the metal at those points tightly against the
mating part. It is frequently applied to the end of a screw or to the face of a nut at the edge of the screw
thread. In the case of a flush screw head, the surrounding metal is sometimes staked so as to project into
the screw head slot, thus locking the screw in position after tightening.
6.3.6 Merchant Quality Steel. Merchant quality steels are those steels that are not suitable for
applications that involve forging, heat treating or other operations in which internal soundness or relative
freedom from surface imperfections is of prime importance.
6.3.7 Autofrettage. The application of such interior pressure to the bore of a cannon tube
as will deform the inner portion of the wall of the cannon tube beyond the elastic limit that would be
reached by the explosion of any charge to be used subsequently in the gun.
6.4
Miscellaneous notes.
6.4.1 Notification. Not less than 14 calendar days prior to performing the initial rifling operation, the
contractor will furnish written notice to the authorized Government representative of the time, date, and
location so that the representative may witness the rifling operation.
6.4.2 Quality and inspection requirements. When warranted, the contract should specify the
application of ISO 9002, as appropriate.
6.4.2.1 Sampling inspections. Sampling procedures are in accordance with ASQ Z1.4.
6.5 Suggested steels. The following is a list of suggested steels based on drawing callouts. This list is
furnished for informational purposes only and its use does not excuse the bidder or contractor from the
sole responsibility of meeting all contract, drawing, and specification requirements. The UNS (Unified
Numbering System for Metals and Alloys) equivalents may be used in lieu of the suggested steels listed.
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