Author Topic: Why did short rails crack???  (Read 689 times)

0 Members and 1 Guest are viewing this topic.

Offline briang2ad

  • Hero Member
  • *****
  • Posts: 2688
Why did short rails crack???
« on: December 26, 2020, 02:58:25 PM »
Enjoy one of the nicer Cz 75 vids out there:



I’ve heard of the rail crack issue on early guns but was it because of the rail length OR metallurgy issues?

Thanks.

Offline Earl Keese

  • Hero Member
  • *****
  • Posts: 4354
Re: Why did short rails crack???
« Reply #1 on: December 26, 2020, 04:01:02 PM »
I think it was because the trigger return springs were too strong.  ;)

Offline SI VIS PACEM PARRABELLUM

  • Hero Member
  • *****
  • Posts: 4159
Re: Why did short rails crack???
« Reply #2 on: December 26, 2020, 04:03:21 PM »
I read somewhere years ago that it was a metallurgical issue that was later corrected.

Offline bregma

  • Newbie
  • *
  • Posts: 23
Re: Why did short rails crack???
« Reply #3 on: December 26, 2020, 07:35:39 PM »
I have spent countless hours researching short rails- lots of stories of it, but never have I been able to find any verification of a cracked frame. If anyone has a picture I'd love to see it.  Myself I have a hard time believing that a gun forged from tool steel would have metallurgical issues. Seems like overkill to me.  I have a couple short rails and shoot one occasionally - never worried about it cracking though,

Offline SI VIS PACEM PARRABELLUM

  • Hero Member
  • *****
  • Posts: 4159
Re: Why did short rails crack???
« Reply #4 on: December 27, 2020, 05:28:50 AM »
I have spent countless hours researching short rails- lots of stories of it, but never have I been able to find any verification of a cracked frame. If anyone has a picture I'd love to see it.  Myself I have a hard time believing that a gun forged from tool steel would have metallurgical issues. Seems like overkill to me.  I have a couple short rails and shoot one occasionally - never worried about it cracking though,
The problems supposedly happened on the earliest guns so I doubt you are going to find pictures and or much verification since there was no internet in the mid 70's and people were not walking around with cameras snapping pictures like they do today. There certainly wouldn't have been any of those guns in the US at that time. The frames are forged but I don't think they were making them from tool steel and today the frames are cast.
« Last Edit: December 27, 2020, 05:33:12 AM by SI VIS PACEM PARRABELLUM »

Offline briang2ad

  • Hero Member
  • *****
  • Posts: 2688
Re: Why did short rails crack???
« Reply #5 on: December 27, 2020, 12:45:22 PM »
I’ve seen a pic of one that broke in the rear years ago.  I just cannot see the reason being a shorter rail.  I think we gun enthusiasts see diabolical reasons for any change. 

But... maybe Earl is right,

Offline eastman

  • Hero Member
  • *****
  • Posts: 3390
Re: Why did short rails crack???
« Reply #6 on: December 27, 2020, 08:43:29 PM »
An incorrect heat treat might have caused a problem which left frames brittle. That's just a theory based on the early 03 Springfield experiences.

Balancing hardness and toughness is an equation that has to be solved. The early partially hardened 1911 slides comes to mind.
I don't look like my avatar!

Offline Psyop96

  • Hero Member
  • *****
  • Posts: 2377
Re: Why did short rails crack???
« Reply #7 on: January 14, 2021, 04:44:52 PM »
The author of some of the best sources of information on CZ 75 history released his latest book, "CZ 75 Pribeh ceske legendy" (Story of a Czech Legend) by David Pazdera in the Fall of last year. This one has more detailed information on the building, testing and serial numbering than the earlier works. It is in Czech so requires the use of an e-translator and some knowledge of the language to work through the odd translations that can show up. This makes for a very slow read of the book but hopefully, correct translation. There is about a page length of mention on the Spanish cast frames.

Most of the frames for the short rails were forged. CZ started moving to casting of the frames in 1978 but had made only 200 at year-end. With its cast frame production capacity of only about 200 a month, the company sought to add capacity from another source. Some negotiations on production of pistols outside of Czechoslovakia had already started in 1977 between Merkuria (Czechoslovak exporter) and the Spanish company, Alfa in Eiba. An agreement was concluded in 1979 with Alfa to produce cast frames to augment UB production. In March 1979, tests on Spanish frames revealed cracks that were also observed on UB cast frames. It resulted in the decision to beef up the frame and slide for the second generation design. With this design change, the new Spanish frames first arrived in January 1980. While this co-operation did not meet expectations, it did help CZ significantly increase production in the early 80s.  By the mid-80s, CZ had ceased to use the Spanish source.

This would seem to indicate: The cracking issue was related to the cast versus forged frames used for the short rails starting at the end of 1978. Spanish frames were not used in short rail production. There is no mention of the disposition of the fewer cast frame pistols made before the cracking issue was discovered in early 1979.


Sent from my iPad using Tapatalk

Offline Russlock

  • Newbie
  • *
  • Posts: 2
Re: Why did short rails crack???
« Reply #8 on: January 15, 2021, 11:11:15 AM »
I have spent countless hours researching short rails- lots of stories of it, but never have I been able to find any verification of a cracked frame. If anyone has a picture I'd love to see it.  Myself I have a hard time believing that a gun forged from tool steel would have metallurgical issues. Seems like overkill to me.  I have a couple short rails and shoot one occasionally - never worried about it cracking though,

I have to agree with you, from what research I've done it seems to be Fuddlore.

Offline SI VIS PACEM PARRABELLUM

  • Hero Member
  • *****
  • Posts: 4159
Re: Why did short rails crack???
« Reply #9 on: January 15, 2021, 11:41:27 AM »
I have spent countless hours researching short rails- lots of stories of it, but never have I been able to find any verification of a cracked frame. If anyone has a picture I'd love to see it.  Myself I have a hard time believing that a gun forged from tool steel would have metallurgical issues. Seems like overkill to me.  I have a couple short rails and shoot one occasionally - never worried about it cracking though,

I have to agree with you, from what research I've done it seems to be Fuddlore.
Read the post above from Psyop96. There's good info there and it provides some clarification.