300 Win Mag to 375 ? ? ?

Discussion in 'Technical Questions & Information' started by SD Hunter, Oct 8, 2005.

  1. SD Hunter

    SD Hunter New Member

    Oct 8, 2005
    South Dakota
    Just wondering if anyone knows if there has ever been a project to take the 300 Win Mag and neck it up to a 375?

    I have researched all of the reloading manuals and have not found any information that would indicate such an attempt. The only reason that it might be a consideration would be to have a 375 in a standard length action; that is, to avoid going to the longer action that is used for the 375 H&H Magnum. I have a 300 Win Mag that needs a new barrel and I was looking for something interesting to try. I know that the 350 Rem Mag has been wildcatted to the 350-375 with some success.

    Any knowledge, ideas or opinions would be appreciated.


    SD Hunter
  2. Welcome to our nightmare! ;)

    It would be doable. But why don't you just have it converted to a .338 Win Mag? If you went with .375 you would have to have a custom chamber reamer made to cut the chamber, but the .338 would only require a standard reamer. However, if you have the time and money - just do whatever turns ya on! :D

  3. stash247

    stash247 New Member

    Oct 18, 2003
    Central Texas
    Holland and Holland tried such an experiment, back around the turn of the cenury, and it worked out pretty well; 30:06 ballistics, (unfortunately, the 30:06 did not exist, then), and excellent accuracy.
    Roy Weatherby, in the '60's, I think, reshaped the H&H case, some, and built the .375 Weatherby, which has a 10% or so, advantage over the H&H round.
    The .300 Winmag, the 7mm Rem Mag, the 8mm Rem Mag, and most of the rest are the grandchildren of the H&H round, necked down, for velocity, at the expense of barrel life!
    I own several rifles in .375 H&H, all are accurate, all are light, tho some are much lighter than others. My 'pet' is a TCR83, with a J.D. Jones barrel, in the caliber, procured for a Kodiac Island hunt, that Exxon cancelled, with the Valdez! 6#, 4oz, and shoots a ragged hole, if the shots are a few minutes apart, at 100 yds.
    Why try to re-invent the wheel? The .375 H&H will kill any creature on earth, if you get the first shot right; how much more can one ask of an (?) antique cartridge????
  4. stash247

    stash247 New Member

    Oct 18, 2003
    Central Texas
    My last post was slightly in error; you will need an extra quarter of an inch, in magazine length, to accomodate the .375H&H, in a rifle originally built for the .300 Winmag, but if the room is there, use it; if not, perhaps a trade is the cheaper route???
    The .375 is the finest 'all around' cartridge going, and worth an extra couple of bucks, to chamber, on the shoulder, instead of the belt, for accuracy!
  5. SD Hunter

    SD Hunter New Member

    Oct 8, 2005
    South Dakota
    Thank you for your thoughts and ideas. I should have mentioned that I would like the 375 caliber so that it would be legal for use in Africa. As soon as I get the kids out of college, I would like to do an Africa trip. I am aware that a couple of the jurisdictions require a minimum 375 caliber. My plans are still uncertain as to what species I can afford to hunt but I would like to be prepared should I find the right hunt at the right price.

    Also, I should have mentioned that the rifle action that I would like to rebarrel is a Husqvarna. The action is a wonderful marvel of engineering and I dearly love the Husqvarna rifles. This particular rifle has a very pitted bore but everything else about the rifle is great. I have discussed the matter with a gunsmith and we have determined that it can not go to the 375 H&H because of the length; the 375 H&H would require another .24" in the action. Therefore, the idea evolved to consider necking up the 300 Win Mag to 375, thus keeping the same action / magazine dimentions but increasing the bore diameter.

    I looked around on the internet and came up with some load data which is listed for the "375/338 (375 Taylor)".
    The web address is: http://geocities.com/bw_99835/375Taylor.htm

    In comparing the load data with my reloading books for the 375 H&H, it appears that the 375/338 (375 Taylor) is about 50 FPS slower than the 375 H&H. I previously had a 375 H&H which I found to be more accurate when loaded in the mid range rather than the maximum. I found that I liked the caliber but did not care for the particular rifle and traded it off.

    Does anyone know of other sources of data or history for the 375 Taylor?

    Additional thoughts or opinions would be appreciated.

  6. JohnK3

    JohnK3 New Member

    May 5, 2003
    Treid to find some info on www.chuckhawks.com but he is silent on the .375 Taylor.

    I'll try to hunt up some more info, if I can find my "Cartridges of the World" book.
  7. You may want to do some research on minimum power levels for cartridges in the countries you plan to hunt. They may require a minumum velocity, as well as caliber, for any cartridge used. While this may include the .375 H&H, it may exclude the Taylor version. :eek:
  8. AGB

    AGB New Member

    Feb 16, 2005
    Brasilia, DF, Brasil
    Newbie to real men guns question:
    Does a .375H&H kics too much harder than a 30-06?
    I got a 30-06 and added a recoil reducer pad because I saw it too hard to use.
  9. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    30-06 8lb rifle 150gr bullet:

    recoil energy= 17.6
    recoil velocity = 11.9

    375 H&H 9lb rifle 270gr bullet:

    recoil energy = 36.1
    recoil velocity = 16.1
  10. stash247

    stash247 New Member

    Oct 18, 2003
    Central Texas
    A plausible answer to the conversion question; How about the .416 Rem Mag? Equivalent power, std action, bigger bullet. Good deal, taken as a whole.
    To the recoil issue, the .375 H&H is a 'pusher', not a 'slammer', and is a pleasant round to shoot, from an erect posture. I'm 5',10", 153#, and frequently empty 50-60 cases, at a standing, behind a 'tall enough' bench.
    When one arrives at the desire for 'middle bore' calibers, the rules of physics apply more stringently, than before, in that resistance can equal pain, if one 'fights' the rules. Shoot from a bench at a height that your torso is, essentially vertical, and 'roll' with the shot, and they are relatively painless; bend over, lean in, so as to present a 45* angle, torso to recoil, and they will pound you.
    Shot right, they are the best going, with plenty of energy, and recoil a little girl can manage. Terry
  11. AGB

    AGB New Member

    Feb 16, 2005
    Brasilia, DF, Brasil
    IPT and Stash,

    Think I won't try shooting a .375 in a long while. Twice as much. No big deal. I do not hunt, and even if I did, there is no such a big game around to make it usefull. Thanks!
  12. Duane

    Duane New Member

    Feb 28, 2006
    I would advise you to do your cartage history. The 300 Win and 300 H&H both originated from the 375 H&H. As well as the 7 rem mag, 338, 6mm H&H, 7mm Weatherby, 300 Weatherby, and quite a few others. The 300 win came out in the late 30's after the 300 H&H won the Wimblton open (1000 meter shoot). My advice is these, if the 300 Win wildcat is a progression, do not regress, buy a 375 H&H
  13. Meplat

    Meplat New Member

    Mar 19, 2006
    Stash, can attest to that. The weekend after my youngest sister got her hunter's certification, she couldn't wait to go to the range with me and show me her shooting prowess. We started off with a .22 rimfire, then she asked to shoot the .308 I had brought along. Got along well enough with that one, and wanted to shoot the 7mm Rem Mag. Was a bit leery, but decided to let her have at it. Liked it quite well. She then wanted to try the .375. Thought "Nah...don't want to make her gunshy on her first weekend". But, thirteen year olds can be quite persistant. Figured what the heck, she won't do it but once. Suggested she stand to do it, but wanted to shoot it off the bags. Recoil spun her around about halfway on the bench, and she couldn't wait to get downrange to check out where she had hit. To my amazement, it was solidly in the black. To double my amazement, once back behind the firing line and the "all clear" had been given, she asked to shoot it again! I fully expected to have her flinch up and put one in Maggie's drawers if she got lucky. She hunkered down, loosed another round. When the signal was given to go check the targets again, you could have blown me over with a breath. The second hole was touching the first. Guess being 90 lbs, limber as a willow and young to boot has it's advantages.
  14. Birdman

    Birdman New Member

    Mar 24, 2006
    Why make the change at all? The 375 is not buying you much in velocity!
    180 grain bullet 300 winmag velocity=3070
    180 grain bullet 375 velocity=3095 a difference in drop @300 yds of about 1/2 inch.
    Stick with the 300 Winmag. Ammo, should you leave your's at home is easier to find.
  15. bryanr1

    bryanr1 New Member

    Mar 18, 2012
    b.c canada
    i have a 300 375 its called a 375 marsh mag . ive worked loads for it and its very accurate