PUBLIC Forums => Public Forums => Technical Assistance => Topic started by: Dalibor on September 29, 2011, 04:01:36 PM

Title: S&W MIM hammer failure
Post by: Dalibor on September 29, 2011, 04:01:36 PM

Friend of mine bought S&W mod. 60 with MIM(metal injection mold) hammer, serial DAVxxxx a year ago, fired a box of .38spl and noticed inconsistent triger pull (as owner said: every time it is lighter and lighter). After few trigger pull measurement we decided to open it up and see what is wrong.... here is what we found:

(http://img820.imageshack.us/img820/160/21138627.jpg)

and detail marked on previous picture:

(http://img190.imageshack.us/img190/8498/pukotina.jpg)

Question is what is the possible reason for this crack (fall or incorect use can be excluded)?

Title: Re: S&W MIM hammer failure
Post by: winterh on November 30, 2012, 12:02:51 PM

Metal injection molding, or better known as investment casting. It boils down to a powdered metal placed into a ceramic wax cast mold.
Upon heating the metal becomes molten annd assumes the shape of the cavity. As far as I know the first to use this was Thompson Center in the manufacture of the Contender pistol.
Today it is used widely throughout the industry. Get another hammer. ICs don't repair well unless it's a clean break. In that case any good gunsmith should be able to braze it back together. The crack you show is a bad casting....HW