Thinking of re-chambering my .30-.378....looking for more velocity

Discussion in 'Long Range Hunting & Shooting' started by Marine sniper, Jan 10, 2008.

  1. Marine sniper

    Marine sniper Well-Known Member

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    I built a .30-.378 on a Hall single shot action, 34 in. Pac-nor 3/3 barrel. I have not fired it yet and have not bought any brass for it. I am considering re-chambering it to a hotter .30 cal, .300 Phoenix, .300-.416 improved, etc. Basically I am looking for advise and maybe some experience with the even bigger .30 cals. In a set up like mine how much velocity is going to be gained in something like a 220-240 gr. bullet. How available are dies for the bigger cartridges, etc.

    Thanks,
    John
     
  2. gamedog

    gamedog Well-Known Member

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    I'd leave the 30-378 as is. Get a 338 if you want to shoot heavier bullets. The 378 case is pushing that bullet rather well , but at the expense of powder and barrels. Stepping up further into a 416 case would exaggerate that even worse.
     

  3. J E Custom

    J E Custom Well-Known Member

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    John

    I have to go along with Gamedog. I have both ( A 30/378 and a 338) and
    they each have there purpose.

    The 30/378 is very fast with a 200gr bullet out of a 27" tube and the 338
    shoots the 250gr AB and the 300gr SMK very well.

    My 200gr load for the 30/378 pushes it 3273ft/sec and groups .091 5 shots
    @ 100yrds with 114 grs of 50 BMG.

    With 7 more inches of tube you should gain 150 to 200ft/sec more. And
    with 126 to 132grs capicity the potential is there for the 225gr and the
    250gr bullets.

    At one time powders were to fast for the 30/370 and even though there
    are slower powders now it's hard to utilize the case to its fullest,So going
    to a bigger case does'nt gain you much. and barrel throat life is very short
    (Arround 200rds some erosion has already started.

    I was going to blow out the shoulders to 40o for more case capicity
    but changed my mind after loading for it.

    Try it first and I dont think you will be disapointed, The brass even though
    it is expensive it is still cheaper than custom brass.

    J E CUSTOM
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I would be very suprised if you would get any more velocity from any of the 30 cal wildcats based on the 416 Rigby case. The reason is because they are very similiar in case capacity to the 30-378 and in most cases, the Rigby cases are not designed to handle high pressure loads as they are designed for a load that drives a 400 gr 416 cal bullet to 2400 fps and thats it, this is with very mild pressure. Sure you can jump the pressure up but your case life will decrease dramatically.

    My 300 Allen Xpress is based on the 338 Lapua case. This capacity is actually quite a bit smaller then the 30-378 but I am getting some truely impressive performance out of it for one reason, the Lapua case will take dramatically more pressure then the Wby case and still have a good case life. In my 30" 300 AX, I started testing with the 208 gr A-Max and settled on a load that is producing 3420 fps. Yes, this is a high pressure load but bolt lift is effortless, extraction is great, no ejector mark on case head, no primer loosening and this by the way is not the highest load I tested. She pushed near 3500 fps before I decided that was enough. Just started to feel the primer pockets loosening and a bit of bolt resistance on that those loads.

    My point being, you do not have to go with a larger case all the time, the 300 AX has about 10 grains less volume then the rounds your talking about but it has a huge advantage in case strength and quality for that matter.

    In addition to that, cases are less costly then the Wby cases.

    Before you do anything however, shooting your 30-378 to see how it does is the smart thing to do. It may suprise you and you may well be happy with that level of performance and a factory chambering is much easier to deal with.

    Kirby Allen(50)
     
  5. Marine sniper

    Marine sniper Well-Known Member

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    Thanks guys, bug holes at 100 yards !! sweet ! I plan on trying 220 and 240 Sierras and 210 Berger's. Not sure if the Berger's will hold up to the velocity. The last time I spoke to Berger about it was about 10 year ago when I built a .30-.378 for a buddy and at that time they did not like th e210's going that fast. The rifle has a 10 twist.

    JE, can you give me a few pointers on primers and powders. I assume Fed 215's but I have been out of the game a few years and some of the new powders are a little foreign to me. Any other bullets you might suggest?

    Thanks,
    John

    You answered as I was typing, thanks Kirby for your input as well. I emailed you directly this morning. Later this year, or perhaps early next year we will talk about your .338 Allen.
     
  6. J E Custom

    J E Custom Well-Known Member

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    30/378

    John

    The primers that get the most velocity are the Fed 215s.

    The best standard deviation has been with the Rem 9 1/2 mag
    primers(5) but at a loss of about 30 ft/sec.

    As far as powders the slower the better ( H869, H50BMG) except
    H870 I did'nt have any luck with it.

    Premium Bullets in the 200gr to 225gr range (Nosler partition in 200gr
    & 225 or 200gr accubonds would be my recommendation.

    The real trick to building a Weatherby that shoots is minimum head
    space (.001 or less) and with the standard Weatherby freebore you
    can load hard for velocity,

    Please let us know what velocity and performance you get with that
    long barrel.

    Good luck
    J E CUSTOM
     
  7. Marine sniper

    Marine sniper Well-Known Member

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    Thanks for the help, I will let you guys know how the rifle does.
     
  8. Buffalobob

    Buffalobob Writers Guild

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    At the risk of being told I am wrong, I will offer the following advice.

    If you have such a well cut chamber, then headspace on the belt. If your chamber is cut sloppy then headspace on the shoulder to compensate for the excess.

    With a minimum headspace chamber the soft brass will like to grow right in front of the belt and your resizing die will not do the job of getting it back down to where it will chamber again. At this time you have three choices. 1 get new brass. 2. Order the belt squisher die from the guy in Florida. 3. grab up your full lenght die and slap the base down on a belt sander until some is gone.

    If you choose #3 then you will need to run a piece of fired brass through it and carefully adjust the die to just meet the belt. Once you know where that is then set the lock ring and you are good to go.
     
  9. Wild_Bill

    Wild_Bill Well-Known Member

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    Barrel

    Hi I think you should be careful with the 3 grove pac nor brl. the lands are usualy wide and they can have a tendency to scolope out on the top and look like large dishes on them this allows gas to get past the projectiles as they are going down the bore. Also the 3 grove might be hard on thin jacketed projectiles like Bergers and A Max's.

    Hope it works for you but don't get the barrel to hot.

    Also be carefull as sometimes the pac nor barrels are not as hard as other brands so run it in well to work harden the bore and the heat from firing it will also heat treat the bore.

    Cheers Bill
    Australia