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Rockwell C test

upjumtddeblupjumtddebl Member Posts: 363 ✭✭✭
edited November 2010 in Ask the Experts
What are the range of RC requirements for parts such as barrels,receivers and bolts? would they be different for rimfires than those required for highpowers?

Comments

  • cussedemguncussedemgun Member Posts: 985 ✭✭✭✭
    edited November -1
    Sir,

    Hardness is just one characteristic of modern ordnance steel. There are many different steel formulas in use & each one will be slightly different.

    Modern gun steel needs to have a high tensil (bursting) strength while being resistant to work-hardening. Hardness will change the qualities such as machinablity, ease of finishing, & wear resistance, as well as tensil strength.

    To quote a Rockwell test value & be meaningful, we would have to know;
    The steel type (carbon content)
    Intended use (barrel, moving part, spring)
    Desired wear quality

    In short, hardness is only one factor that needs to be balanced with many more when an engineer designs a gun part.

    Jim
  • upjumtddeblupjumtddebl Member Posts: 363 ✭✭✭
    edited November -1
    so the rest of the story is I was given 6 guns that were in a safe during a fire, some 22's a SKS a Marlin 30-30 and a Eddystone P14 converted to 7mag although all the wood was lost as well as the alloy scopes. however the brass magazine tubes in the 22s survived but most of the springs lost there temper. A friend of mine that owns a machine shop that Mfg go/no-go gauges for threads has offered to RC test the guns to see what changes took place. its really just a experiment to see what happens inside a gun safe (during a fire) and I was looking for a baseline of specs for comparison since all of the guns experienced a different degree of damage. any more thoughts?.By the way,no I dont want to shoot any of these guns
  • cbyerlycbyerly Member Posts: 703 ✭✭
    edited November -1
    If the springs have lost their tension and the metal is blistered in any fashion, they are unsafe to restore.
  • SoreShoulderSoreShoulder Member Posts: 2,669 ✭✭✭
    edited November -1
    Springs are tempered at a lower temperature than guns, so it is at least possible that the guns are ok, though it would seem that chances are pretty slim that the temperature only went up by a few hundred degrees more than what it takes to ruin springs, but not more than that.

    Give 'em a blue pill. Proof test them. Find a way to put in a 25% overcharge and fire them remotely.
  • Hawk CarseHawk Carse Member Posts: 4,296 ✭✭✭
    edited November -1
    All those guns are made out of different alloys with different hardnesses at the compromise of strength and machinability. It is unlikely the factories will tell you their specs.
    If you could round up an unburnt gun of the same make and model, you could do a side-by-side comparison of hardness. Nobody would notice the little dimple of a Rockwell indentor on a used gun.
  • cussedemguncussedemgun Member Posts: 985 ✭✭✭✭
    edited November -1
    Sir,

    The short version (the one that doesn't require a 4 year degree)

    Heat treating of steel is done in 3 main steps;
    pre-heat
    quench
    draw

    The draw process for springs is lower temp. than say a barrel but only because they draw very little of the temper back out. The fact that the springs are now flat indicates too high a prolonged temp. for any heat treat condition to survive.

    Not knowing the temp. reached, the %oxygen of the area, & the duration they were exposed makes the whole thing SCRAP!

    Put them aside & wait for the next "Feel-Good Liberal gun buy-back"

    Jim
  • upjumtddeblupjumtddebl Member Posts: 363 ✭✭✭
    edited November -1
    Hawk carse, It seems to me that your idea of comparing guns is the way to go as it would actually provide the numbers I'm looking for. as for the fact that burnt guns are most likely not safe to shoot is a well established fact but my question is one of metallurgy. thanks everyone
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