Joined
·
681 Posts
I don't know what steel is used in K-80 receivers, perhaps someone can enlighten me, but it is probably similar to 4140/50 HT or 4340. That would put it in the DIN 1.6+++ to DIN 1.7+++ catagory. The yield of 4340 heat treated to a range of Rc 35 is 103,000 psi. Not heat treated, (annealed) Rc is 17, it is 62,000. 4140/50 would be less but not by much. These are not case hardening steels, but through hardening. They are also excellent for nitriding, which would give they an ultra high surface hardness, somewere around Rc 68, I do not believe that Krieghoff does this but others may. In the inside of my K-80 receiver there is a mark from the diamond point used in hardness testing, so obviously Krieghoff has a certain standard. Given the high yield point of this type of alloy, I believe that the only possible cause of a "blow up" must be some sort of an obstruction probably coupled with an ultra hot load. HMB points this out in another thread. The steel used in receivers is just too strong for anything else. These alloys are common in aerospace applications and I would very much doubt that there is a possibility of metal fatigue involved.
Incidentally about a year ago. I sold a TM-1 to a shooter who had blown up a TMX the previous week. He was a brand new reloader. It ain't just Krieghoffs.
J Bergman
Incidentally about a year ago. I sold a TM-1 to a shooter who had blown up a TMX the previous week. He was a brand new reloader. It ain't just Krieghoffs.
J Bergman