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Thread: More "Old" School

  1. #1
    Senior Member Doc Sharptail's Avatar
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    More "Old" School

    I've done a bit more work with the old 140. I took the 130 pivot block off, and put on a modified 13-89 block, to give the bbl a bit of tightness. I also cleaned up the transfer port opening on the bottom of the bbl.



    5 of the JSB Exact Heavy at 12 Meters. It looks like I'm getting the vertical stringing a bit more under control. That's 5 pumps for each shot.

    Here's where the old school comes into play:



    That's an early 60's Weaver B-4 4X scope. It groups well at 12 Meters, despite it's uncoated lenses and 50 yd parallax setting. That old Weaver has taken a boat load of grouse and rabbits for me. It sat for years atop my 52 repro....



    Burris tip-off rim-fire rings. Hard to come by these days. I stumbled across these at a small rural gunshow years ago, and jumped at them.

    I think in order to fully test this 140 bbl, I'll have to get it into a sbk steel breech.
    I'm kinda torn about how to accomplish that. I do have a phase 2 13-22 that the bbl will direct fit into the modified SBK breech. The difficulty comes in deciding whether to further modify that breech to line up with the breech screw hole on the 140. That of course opens up a whole 'nother can of worms for me- to inlet the stock for a breech band for the SBK breech or not??? I really do it to myself at times

    Regards,

    Doc Sharptail
    Last edited by Doc Sharptail; May 17 2012 at 02:08 AM.
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  2. #2
    Administrator AirGunEric's Avatar
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    Looks good.

    Which/what mounts are those on the barrel?

  3. #3
    Senior Member Doc Sharptail's Avatar
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    Quote Originally Posted by AirGunEric View Post
    Looks good.

    Which/what mounts are those on the barrel?
    Those are the current "Crosman" branded inter-mounts- I think 459 was the number on the clamshell wrap... one of the cross bolts is starting to strip already. I won't be using them much longer, I hope.

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

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  4. #4
    Administrator AirGunEric's Avatar
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    The 459 aluminum mounts are not strong- they really are a "poor man's" steel breech for a Co2 gun. The Benjamin units are better, but may not be the correct size for alot of applications.

    Can aluminum be hardened in some way? I.e. like steel you can heat and add some carbon to harden the surface- anything similar that can be done for aluminum I wonder (? I'm no metallurgist).
    I'd say I care- but I'd probably be lying...


  5. #5
    Member Dukemeister's Avatar
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    Quote Originally Posted by AirGunEric View Post

    Can aluminum be hardened in some way? I.e. like steel you can heat and add some carbon to harden the surface- anything similar that can be done for aluminum I wonder (? I'm no metallurgist).
    Not for aluminum, the only surface hardening you could do would be cold work like shot peening or a similar process. But there is no real case hardening process for aluminum. Some aluminum alloys can be age hardened, (heat treated) but it's pretty much a through hardening. If the alloy is a 2xxx, 6xxx, or 7xxx series it can be age hardened. Some cast al-alloys are also heat treatable. My guess is that airgun aluminum bits (like mounts) are made from 6061 alloy which is the cheapest and most commonly used structural al-alloy. 6061-O is annealed, and 6061-T6 is age hardened. You often see the term "aircraft grade" to describe aluminum alloy, but of course that doesn't tell you which one. In order of increasing strength it is 6xxx, 2xxx, then 7xxx (in general). You wont find much 6xxx series on an airframe (if any), as the higher strength stuff is used. Metallurgy lesson over for today...
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