MIL-STD-1258 Chromium Plated 5.56Mm, 7.62Mm, And Caliber .30 Small Arms Barrel BoresThis document establishes visual comparision standards for workmanship type defects in chromium plated 5.56MM, 7.62MM, and Cal .30 barrel bores.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10

MIL-STD-1258(WC)

30 June 1972

5.2.1.8 Figure 14 represents pitting and nodular build-up on the

land.

5.2.1.9 Figures 15 and 16 represent severe flaking of the chrome

plate. A multitude of cracks in the chrome plate and areas of peeling

are evident In the illustrations.

5.2.1.10 Figures 17 and 18 represent typical electrode burns.

This condition results when the electrode is not centrally positioned

in the barrel bore or the electrode is bowed or bent.

5.2.1.11 Figure 19 represents a rough surface condition in the

chamber of the barrel. A replica of the basic metal surface roughness

is evident on the chrome surface. This roughness in the chamber was the

result of a mild acid etch prior to the application of the chrome plate

and was caused by an inadequate alkali rinse after electropolishing. The

surface roughness of the example Illustrated by this figure measures up

to 45 root-mean-square (rms).

5.2.1.12 Figure 20 represents a "frost" deposit of chromium plate,

This condition is most apt to result when one of the principal variables

in the plating process, such as high current density area, tends to

accelerate chromium plate build-up.