Universal M1 Carbine Slide for Late Model Carbines

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jski

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Those interested in a new late model Universal slide "made of 4130 steel heat treated to 35Rc" can go here.
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I bought one of these puppies and replaced the factory slide strictly as a precautionary measure. Fit perfectly as is ... without modification.
 
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Someone care to comment on "4130 steel heat treated to 35Rc" as a quality of steel? Extremely good? Very good? Etc.
 
In my experience, the weld is where the Universal slides fail. 4130 can be welded successfully with proper post weld stress relief.
 
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.
Universalbrokeslide2.jpg
 
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.
 
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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.

I suspect that it would be better as technology and machining have advanced but it would probably be expensive. The carbine clones that are available today via Kahr or MKS (I think) use more modern tech and mfg. techniques but use it to reduce costs instead of strength imho.

Same issue comes up on AR bolts. Mil-spec calls for Carpenter 158 which is a proprietary steel alloy formula steel with the tech of 1950's-60's. Some companies make these bolts out of newer steel alloys that have available specs to the consumer and mfg. but they are not mil-spec. Supposedly they are better than mil-spec on toughness, longevity, etc.

You also see disputes on commercial versus military buffer tubes, the aluminum alloy used in uppers and lowers, billet versus forged, etc.
 
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.
View attachment 807092
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.
IMG_20180629_005706.jpg
 
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.
View attachment 814297
The snippet you sent has the diagnosis:
The cause has been traced to occasional problems with heat treatment for proper hardening.
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".
 
Nightlord is probably on to something. Heat treat is not the only determining factor in part failures. Any good machinist or engineer knows that sharp inside corners create stress risers that are prone to cracks. I have seen numerous failed parts directly traceable to that very thing. Even with proper heat treat I would not want a sharp inside corner on any of my parts.
 
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.....:thumbup:

Might want to grease that area, though. Lubriplate or Synthetic wheel bearing grease work well.
 
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.....:thumbup:

Might want to grease that area, though. Lubriplate or Synthetic wheel bearing grease work well.
I always welcome input from those better educated than I on any particular subject.

Thanks for your input!
 
jski,
35 Rockwell "C" scale is not hard.

As previously posted- grease is definitely needed/required.

Give it time,it will work harden & crack.
 
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