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Are ALL wthby magnum catridge dimensions the same?

JustC
I have an action that I was thinking of selling the ss barrel and redding custom series dies off of, and re-barreling in for 30-378 wthby mag. It was originally a 257 wthby mag (MK V action), currently, it is a 6.5-06 ackley improved. Can I simply rebarrel the action and have the boltface be correct for the 30-378? I had to install a ring in the bolt face which grasps the 06 case in the magnum action, so by simply taking the ring out, it is back to a magnum action.

A great rifle with a junk scope,....is junk.
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Comments

8 comments

Date Votes
  • cpermd
    The boltface is larger on the 378.
    You will have to open up the face to .604" at least,
    maybe another 0.002"
    cpermd
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  • Iconoclast
    Justin, the .257 has nominal rim diam of .512", belt of .530" while the original .378 case has rim of .582" & belt of .602" The smaller diameters were used on the .375 Weatherby, but the .378 inherited its dimensions from the .460. I'm not sure which serves as the basis of the .30-378, but suspect your plan would not work.
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  • Iconoclast
    Stupid server is screwed up . . . .

    Edited by - Iconoclast on 08/01/2002 14:29:18
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  • aglore
    First of all, you will need an action that will handle a cartridge of 3.5" length. The action that the 257 WBY is in will not fit the 378 WBY case as that case is 2.9" long.

    AlleninAlaska

    Free men are not equal and equal men are not free
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  • pigeoncreek1
    The answer is "yes" it will work..

    All Weatherby Magnum actions, with the exception of the .224, are the same dimensions. All you need to do is get your bolt face opened up to the .378 dimensions, and change the spacer in the magazine box to accomidate the .378's added length, and get your new barrel screwed in...If you do it, make sure you fill me in on the results!!



    Gun control is hitting your target
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  • rwpiper
    No one has mentioned the bolt stop. There is a spacer in the magazine which has to be removed. Therefore, I believe the groove on the bottom of the bolt which determines where the bolt is to stop will have to be longer.
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  • JustC
    Ok guys, assuming that the actions are the same, and assuming I had it opened up (the bolt face), would the finished bolt and action hold the kind of pressures that the 30-378 creates? All reloading data shows that the trajectory and power of this cartridge are not realized until the bullet weight is in the 200gr+ range, otherwise, it is minimaly better than the 300wthby mag. If this is the case, I will have my 28" barrel twisted heavy for the lightest bullet it will accept to be 180gr but perfect for 200gr+. Therefore, my pressures will be high with the bullet contacting the rifling, (which they say is almost a must for this over bored cartridge, with respect to barrel life).

    Or,....would I be better served to just barrel it in 300mag? (wthby or win)?

    A great rifle with a junk scope,....is junk.
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  • pigeoncreek1
    The .30-.378 is the ultimate long range caliber in my opinion. That being said, If your keeping it under 300 yards, the .300 WBY will serve you just as well, easier and cheaper to reload & less recoil/muzzle blast. My favorite caliber is the .300 for all around hunting, but if youre looking at some long distance shooting, the .30-.378 is the answer!!

    Gun control is hitting your target
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