mark v action

Discussion in 'Gunsmithing' started by cummin_un_glued, Oct 2, 2012.

  1. cummin_un_glued

    cummin_un_glued Well-Known Member

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    ok guys bear with me because i know very little about these actions and i'm trying to learn. i did find this in the sticky

    Long actions with a bolt face .Dia of .540 +/-
    257 Weatherby, 264 Win Mag, 270 weatherby Mag, 7mm Rem Mag, 7mm Weatherby Mag, 7 STW,
    7mm Rem Ultra Mag, 300 H & H, 300 Win Mag, 300 Weatherby Mag, 300 RUM, 303 Brit,
    8mm Rem Mag, 338 Win Mag, 340 Weatherby Mag, 338 RUM, 375 H & H, 375 Weatherby,
    375 RUM, 416 Rem Mag, 458 Win Mag, and the 458 Lott.

    Long actions with a bolt face .Dia of .585 +/-
    30/378 Weatherby, 338 Lapua, 338/378 Weatherby, 378 Weatherby mag, 416 Rigby,
    416 Weatherby Mag, 460 Weatherby Mag, and the 470 Nitro Express

    now is there a difference between the actions or is it just the bolts? i'm assuming the large bolt face actions are maybe bigger all together is this true or can one use an action from the 540 bolt and change bolts?
     
  2. J E Custom

    J E Custom Well-Known Member

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    All 9 lug Mark 5 actions are the same, the only difference is the bolt face and the center feed mag
    box of the .585 actions.

    There is no need to buy a new bolt if you have a .540 bolt and want to go with a .585 size case.
    Just open the bolt face and buy a 378 extractor and center feed mag box with the flat bullet follower
    from Weatherby (under $75.00 for both).

    J E CUSTOM
     

  3. cummin_un_glued

    cummin_un_glued Well-Known Member

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    awesome that makes my search for an action to build off of alot easier then. planning on it being a single shot rifle anyways so i would just need the 378 extractor then correct?
     
  4. Hired Gun

    Hired Gun Well-Known Member

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    If the action is from a .257 or the shorter magnums you will need to extend the slot in the bottom of the bolt in order to pick up the longer cases.
     
  5. J E Custom

    J E Custom Well-Known Member

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    You would need to open the bolt face and buy an extractor if it is the magnum bolt face(.540)

    The .585 bolt faced actions are harder to find and usually more expensive.

    Some of the smaller caliber Weatherbys have a shorter bolt and only 6 Lugs don't buy this one
    for what you want.

    There is one other thing that I forgot. As Hired Gun pointed out, the bolt stop has to be milled
    a little longer if you want it to be a repeater. You said you were going to single feed and if so
    this slot is ok to eject the spent cases.

    J E CUSTOM
     
  6. cummin_un_glued

    cummin_un_glued Well-Known Member

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    Great info guys thanks. So as long as i look for an action from just about any mark v larger then a 257 and make sure its a 9 lug i should be good. Thanks for the heads up about the bolt mod but i plan for it to be a single shot since most of the good bc bullets ran out to the lands wont fit in a box anyway unless you guys know of one that will fit them?

    Also i been reading about in the factory wby rifles they have a "freebore" when having a barrel built can this be addressed? I guess what i mean is are the reamers that guys are using different from the factory ones?
     
  7. Broz

    Broz Well-Known Member

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    The Mark V 's have a generous amount of room in their Mag box. The 338 LM I did off one would except the 300 berger and the 300 SMK into the box even seated at the lands. But it does require a little bit of feed ramp work to cycle the Bergers. I have also built some 7mm-300 wins off this action and with a 180 Berger seated long it would fit and cycle. The average OAL of a round that will fit in the box is 3.800"

    Jeff
     
  8. 270 MKV

    270 MKV Well-Known Member

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    so, if a WBY MKV was built with a 9 lug action...and chambered in 270 win, why was this done??
     
  9. Hired Gun

    Hired Gun Well-Known Member

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    The issue with Bergers feeding in the Weatherby has to do with how the barrel is counterbored. If you just cut it square like a Remington the bullet nose will catch on it and it will be a jam-o-matic. Study a factory take off barrel and you will see the bevel at the bottom of the relief right around the chamber. We use about a 15 degree angle in there to get the really pointy bullets to feed. The bolt stop groove will still need extended even in a single shot if you want to extract live rounds. The free bore can be special ordered built into the reamer or we can get a minimal lead and use a throater for a custom fit.

    No reason to not be a repeater if you want one. The factory bottom metal works good with the big cases. I would also strongly consider a 338 Lapua over a 338-378 Wby. The brass costs the same but lasts a lot longer and only gives up very little in power to the 338-378.
     
  10. cummin_un_glued

    cummin_un_glued Well-Known Member

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    so how much would these bolt modifications cost? would it be worth it to go ahead and try to find the larger bolt action? i have seen a couple guns with the 540 bolt for less then $700. 540 bolt stop modification required check. so with the changes to the reaming of the barrel the freebore can be fixed then to where even with bergers it will be at the lands and be under 3.800 coal? seems i was reading on another forum where guys were out at 4.000 in factory barrels to get them there? does this sound right? i wouldnt be opposed to it being a repeater as long as the coal/mag/lands all lined up as needed.

    i know the lapua would be the smarter choice but its more of a want thing. i want a weatherby/weatherby rifle.
     
  11. cummin_un_glued

    cummin_un_glued Well-Known Member

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    [​IMG]

    as i was saying i'm new to this action and google image search dosnt turn up a 6 lug pic so is this a 6 or 9? being a 300 wby i'm assuming it is the correct 9 lug action?
     
  12. Dr. Vette

    Dr. Vette Well-Known Member

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    9 lug.

    The 6 lug is usually used only in non-Weatherby calibers like 30-06, 270, etc.
     
  13. Hired Gun

    Hired Gun Well-Known Member

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    The 300Wby is the long one and doesn't need the bolt slot cut longer. Just open the bolt face and change extractor. Keep looking. The synthetics go for $600 from time to time on gunbroker.