The method used to create the sear spring mortise in the upper receiver has always made me wonder too... obtaining tools that small would not be an issue, but the obtaining the correct internal shapes and surfaces to that mortise are a machining operation that escapes my gunsmith and hobby machinist mentality...
All I know for certain is that the Germans and the Swiss did it MILLIONS of time... and it was perfect every time... An engineering miracle IMHO.
Even the Stainless Steel guns that were produced under several marketing names by the same manufacturer never produced this mortise to the same perfection as the original guns.
__________________
regards, -John S
"...We hold these truths to be self-evident that ALL men are created EQUAL and are endowed by their Creator with certain UNALIENABLE rights, and among these are life, LIBERTY, and the pursuit of happiness..."
|