How to identify USGI parts

[Mark in Rochester]

In general USGI parts are forged where others may be powder metal - these can be identified by parting lines and ejector pin marks an example can be seen on page 140 of J. Kuhnhausen Garand /M14 shop manual see page 157 also fig 177



Powder metallurgy is a forming and fabrication technique consisting of three major processing stages. First, the primary material is physically powdered, divided into many small individual particles. Next, the powder is injected into a mold or passed through a die to produce a weakly cohesive structure (via cold welding) very near the dimensions of the object ultimately to be manufactured. Pressures of 10-50 tons per square inch are commonly used. Also, to attain the same compression ratio across more complex pieces, it is often necessary to use lower punches as well as an upper punch. Finally, the end part is formed by applying pressure, high temperature, long setting times (during which self-welding occurs), or any combination thereof.

below is a USGI forged T-37 flash hider from Scott Duff's web page



this one is from a auction and I would suspect it is cast