Straw parts
 

I have a 1939 Mauser 42 in very good condition. I have read where Mauser stopped 'strawing' parts in the early 1930's. My Mauser has strawed parts most notably the piece on the right side (thin, narrow, long). I don't remember the parts name. So, would this be correct?

it is the ejector. Probably not strawed, but displaying color from heat treating. Pics would help.

Straw on my 1939 Mauser
 

A photo of right side of 1939 mauser 42

Strawing stopped in mid 1937(on military lugers by Mauser, though they did continue to use strawing on some commercial models).
But yours is a military model and should not be strawed.

Your ejector is red in tone from the hot bluing salts, they give a red tone on some alloys and on parts with different heat treatment. Red tones are often seen on the ejector, extractor, and the receiver of Mausers made from 1937 to 1940- it took Mauser a while to get the salt bath "right".

Strawed parts were still used on commercial Mauser Lugers after 1937. I agree with Don that the one you have is "plum" to "red" in color due to salt bluing and alloy content of the ejector.

It may be a shadow or object behind the gun, but I don't see the Mauser "hump" you would expect on a 1939 frame in your picture. The back of the ear of your frame looks straight in the photo. That change also occurred in early 1937.

It is stamped '1939' above the chamber. 4 digit serial number ending in 01.