How do you tell the difference between mim and machined sears and hammers

by curmudgeon Mon 20 Apr 2020, 14:37

I have a couple of dozen M-1911 sears and hammers collected over the years and I like to separate the mim parts from the machined steel parts. How do I tell the difference between the mim parts and the regular steel parts using simple kitchen table methods?

Many times over the years, I knew people who were going to tear-up Camp Perry only to have the triggers go bad on warm-up day.
I don't want this to happen to me. I want to sort out the mim parts which leads me to my second question.
How do tell the bad mim parts from the good ones?

I have new in package hammer that is labeled unbreakable. In over sixty years, I have only seem one hammer broken and it was a cast part.Are people taking liberty with the language?

I have more than one .45 and I have never had a sear or hammer wear out but one cannot be to carefull.

Joe

by mustachio Mon 20 Apr 2020, 14:58

MIM parts will have casting lines on them where the two parts of the mold meet.

by **Wobbley** Mon 20 Apr 2020, 15:01

MIM is actually a powder metal process where powdered metals are pushed into a die and then fused by almost melting. It’s been used for years in the gun industry. The only way to tell in many instances is to cut the part and do a metallurgical etching. Or look very carefully at alll surfaces and see if you can find any “as sintered” surfaces, but you have to know what to look for.

by jglenn21 Mon 20 Apr 2020, 15:02

the dead giveaway for a MIM part is the small round impressions you'll see in them from the ejector pins.. cast parts have the lines normally

my favorite MIM picture. This was a Bul part.. it lays on my workshop table as a reminder.

How do you tell the difference between mim and machined sears and hammers Broken10

by curmudgeon Tue 21 Apr 2020, 13:28

mustachio: Parts with parting lines are cast.Quite common during WWII.

jglenn21: Thanks for the info. I found a few sears with the circles on the side. Where are the marks for a hammer located?
After thinking about this,I am led to believe that complex shape of hammer used with beavertail grip safeties are mim. I don't a easy way of machining them.

Sorry about the Bold lettering of the title, I don't know how that happened.

Joe

by jglenn21 Tue 21 Apr 2020, 16:25

How do you tell the difference between mim and machined sears and hammers Hammer10

Mim Hammers
these are Wilson value hammers.. other Wilsons appear to be EDM cut parts

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How do you tell the difference between mim and machined sears and hammers

How do you tell the difference between mim and machined sears and hammers

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