Update: Universal M1 Carbine Slide Late Model New
Aside: I've always wonder, had the late model Universal M1 Carbine design been implemented with high grade, top quality steel would it have proven to be a better design than the GI design? Heresy! I know.
Ehhh.....it may have as much to do with that sharp corner resulting in a stress riser as well as the proximity of the weld.....in which case the new production slides may not prove more reliable. Time will tell.Cracked or Broken Slides
Occasionally a slide used by Universal after their design change starting at s/n 100000 will crack or break at the camcut opening that engages the right bolt lug. The cause has been traced to occasional problems with heat treatment for proper hardening. This is not an issue for all of their slides and breaks/cracks on any carbine slide can be caused by several factors related to use, wear improper ammunition, improper headspace and/or a number of other causes. Used carbines by all manufacturers, GI or commercial, should be examined occasionally for conditions that could lead to this problem.
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The snippet you sent has the diagnosis:Ehhh.....it may have as much to do with that sharp corner resulting in a stress riser as well as the proximity of the weld.....in which case the new production slides may not prove more reliable. Time will tell.
If I were really, really fond of a second gen. Universal, I would lay away TWO extra slides, lol!
Fortunately, I have a 1st Gen, so no worries here- it is one of my very favorite rifles and I treated it to a complete GI trigger group. Universal certainly could, on a good day, make a fine gun.
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I believe I could put a 1,000 rounds/day down range for a 1,000 days and not suffer any problems with a slide made of: "4130 steel heat treated to 35Rc".The cause has been traced to occasional problems with heat treatment for proper hardening.
I always welcome input from those better educated than I on any particular subject.It does appear that they radiused the corners on your example better than the old Universal slides. Not too shabby! Should provide new life for many old rifles.....
Might want to grease that area, though. Lubriplate or Synthetic wheel bearing grease work well.