Comments on HOT 7mm's

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by James Jones, Apr 2, 2006.

  1. James Jones

    James Jones Well-Known Member

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    Comments on HOT 7mm\'s

    I'm tinkering with theidea of a LR rig and a hot 7mm was in the mix , called a couple old hunting buddies that I haven't talked to in several onths and one said that hes doing the same thing with a 30" barreled Wby that was a
    30-378 making a 7-378 pac-nor has the reamer and is doing the work. His plan is to get a 180gr Berger VLD to 3600fps , I personaly don't think that is possible but maybe 3400 maybe more
    Anyway I asked why not just a 7RUM or 7-338Imp but he is looking the most he can get.

    Anyhow , what would the velocity differance be between the regular 7mmRUM and a 7mm-300RUM , is their enough differance in the case to warrent the extra work.
    I was also thinking about a 7mm-300Dakota

    Hell who knows maybe the 300RUM with a min cut chamber will be the best bet.

    The rig would be for deer and elk out to 600-800yds but with as little wind doping as possible thats why I was thinking about the long 7mm bullets

    What do you guys think?
     

  2. davewilson

    davewilson Well-Known Member

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    Re: Comments on HOT 7mm\'s

    JD, there is no difference between the 7rum and a 7/300rum.it's the same case.if you're looking for killing power,build a 338 caliber.reason i say this is,i've compared bullet weight/vel/ with the same cases.with the rum case,a 7 will push a 200 gr bullet about 2900.it can go faster but that's a comfortable speed. a 300rum will shoot a 200 gr ball over 3200.but a 338 caliber will launch a 300 gr pill around 2900.all of these velocities are with the same parent case and barrel length.i don't want to start any arguments but i don't think the BC of the 200 wildcat is as good as the 300SMK.the 7 is harder to load for and barrel life is probably half of a 338.IMHO there is no range a 7 can hit harder than a 338.i would take a 30 over a 7 and a 33 over the 30.
     

  3. hjl

    hjl Well-Known Member

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    Re: Comments on HOT 7mm\'s

    Hi,
    What velocity do you think your mate can get with a 200 gn wildcat projectile in the 7-378?
    It sounds interesting to me.
    Regards
    hjl
     
  4. Guest

    Guest Guest

    Re: Comments on HOT 7mm\'s

    [ QUOTE ]
    all of these velocities are with the same parent case and barrel length.

    [/ QUOTE ]

    Excellent post, great info. Slight correction, the 7mm, 300, 375 RUM have all the same case, the 338 is .1" shorter (to allow for a wider array of bullet selections in factory chambering). I currently own two 300 RUMS, a 338 & 375 RUM. All but my factory Sendero sport Lilja 30” #8 contour - all guns have been worked over by Kirby (trigger job, custom stock, Holland QD brake, scope rail hole bored to #8-40) - All track drivers.
    But I couldn't agree more with your assessment. The 338 RUM is the ultimate long range elk gun IMAO. The only minor improvement you could make; ream one to chamber the longer/cheaper/better 300 RUM brass.

    I was going to add the 7mm RUM to my collection but my rocket scientist pal convinced me the 7mm RUM is too *over bore*, the case is ideal for the 338 and works well for the others, (sans the 7mm). I'll add a 7mm STW some day for my ultra long range deer/antelope gun.

    I'll also add the 375 RUM is underrated. I'd pick up another 375 RUM before getting a 7mm RUM.

    [ QUOTE ]
    i don't want to start any arguments but ...the 7 is harder to load for and barrel life is probably half of a 338.


    [/ QUOTE ]

    I disagree, I'd say it's LESS than 1/2, maybe 1/3rd. Sorry for arguing with you Dave /ubbthreads/images/graemlins/frown.gif
     
  5. davewilson

    davewilson Well-Known Member

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    Re: Comments on HOT 7mm\'s

    BB, i wish i had a wife that argued with me like you do. i wasn't specific enough in my cartridge desciption.i was talking about the 338/300rum or edge or whatever it's called giving those velocities.and to be honest, i was gonna say a 33 would last more than twice as long as a seven and stayed conservative with double.

    i'll bet that 375 hits em like the hammer of thor!
     
  6. Buffalobob

    Buffalobob Writers Guild

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    Re: Comments on HOT 7mm\'s

    [ QUOTE ]
    The rig would be for deer and elk out to 600-800yds but with as little wind doping as possible thats why I was thinking about the long 7mm bullets

    What do you guys think?


    [/ QUOTE ]

    A regular 7 mm Rem mag, 7mmWby mag, or 7 STW or 7 RUM will easily do what you want.

    The bearing surface on the 200 gr Wildcat (unbonded bullet) was the same as the Nosler 160 AB give or take a small amount. This is somewhat longer than the bearing surface on a 175 gr SMK which has a BC of 0.6. SS7MM was launching the 200 grain wildcats from a standard 7Wby mag but did not have a fast enough twist to acheive complete stabilization. With a 7 twist 3 groove barrel you could have the option of the heavy bullets or the lighter ones.

    A Weatherby 378 has almost the exact same case capacity as a 338 LM. If you blow them out and neck them down to 284 you have a 7mm AM with and without a belt for all practical purposes. Whether Pac Nor or Kirby will be more precise with the reamer is your decision. A 7mm AM with a 200 gr Wildcat compares favorably with a 30-378Wby with a 240 gr SMK and depends on what you want to assume is the BC of the 200 gr Wildcat.

    For what you want to do you might actually think about a 264 Win mag as something fun to work with and shoot. I want one so bad I just can't hardly resist it any longer.
     
  7. BLASERMAN

    BLASERMAN Well-Known Member

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    Re: Comments on HOT 7mm\'s

    I have all ways wanted a 7mm STW. I finaly have one but have not shot it yet. Have the dies but have not loaded any thing yet. My first experience with an STW was my buddy shoting a deer at over 475 yrds on our eastern shore. His was done by a guy in Pa name Clarance Hammond.Mine has a 1-9.5 twist I am going to try 150 gr bullets.
     
  8. dakor

    dakor Well-Known Member

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    Re: Comments on HOT 7mm\'s

    Dave a 7mm will out perform a 30cal sorry but it is a fact of life. I have both and the big 7's retain more energy, velocity, shoot flatter and have less wind drift. A big 7mm will fill the bill for long range very well. If you could drive a berger 180 even at 3100fps that has plenty of energy and velocity to kill elk out to 1800 yards wich is plenty far for most people. You should be able to drive a 180 around 3300 to 3400fps with a standard 7mm RUM. I was getting 3100fps with a 7mm STW Sendero. When I get my STW back from Chris it will have a 28inch Broughton 5c on it and I should be able to get 3200fps pretty easy with that setup which like I said is plenty for Elk out to a mile or more. I would also like to add at the ranges you are going to shoot a standard 7mm mag or 300win mag would be fine. DC says a 7mm mag with a 175SMK will kill any bull Elk at 1000 yards so I am sure it will have no trouble at 600-800 yards.
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Re: Comments on HOT 7mm\'s

    Dave,

    I will agree with you on several points and respectfully disagree with you on one. Lets cover the points we agree on first.

    The 338 caliber will certainly offer a longer throat life then the large 7mm rounds such as my 7mm AM. THis is hardly debatable /ubbthreads/images/graemlins/grin.gif!

    On averge, the 338 rounds are also easier to load for, less finicky if you will, we agree again.

    Also, on heavy game, a 300 gr bullet will have more physical effect then the smaller diameter 7mm bullet, of course it will, just a bigger hole being drilled though the target, we agree again.

    Now to the one point that I have to disagree with, a 200 gr ULD RBBT 7mm bullet will kick the HELL out of a 300 gr SMK ballistically when both are drive to the same muzzle velocity.

    Doing BC testing with both bullets out to 1500 yards I have found the 300 gr SMK to have a BC right in the .810 range when launched at 3100 fps out of my 338 Kahn. This is out of a 34.5" barrel as well.

    The 200 gr ULD RBBT will produce a BC of .910 to .920 at this same velocity.

    Only real difference is that in the 338 Kahn in the long 34.5" barrel, this is a top load with the 300 gr bullet. In my 7mm AM, 3100 fps is really a puff load and only out of a 30" barrel. Top loads will get you 3300 fps but I much prefer loads in the 3200 fps range simply because they are less finicky with temp changes and seem a bit more consistant in accuracy potential as well.

    So ballistically you can compare these two sets of numbers:

    300 gr SMK....0.810 BC.....3100 fps
    200 gr ULD....0.910 BC.....3250 fps

    Now these numbers are both derived from actual bullet drop over 1500 yards. These are not pure scientific BC values but they were both figured using the same exact method over the same ranges over the same velocities and in the same conditions and elevation.

    As far as on game performance, the 338 bullet offers a bit higher BC value, .375 compared to .355 but both are more then high enough for any penetration on game up to the size of elk for an shot into the vitals. For dee hunting they are both far exceeding what is needed for full penetration.

    SO simply put, while I would agree with you on most points, I have to say that you are incorrect in your comment about the 300 gr SMK being ballistically superior to the 200 gr ULD RBBT 7mm bullet. Simply not the case.

    Then we can get into the debate on recoil. Drive a 300 gr pill to 3000 fps and then drive a 200 gr pill to the same velocity and the recoil will be significantly less for the 7mm.

    Again, I am agree with most of your comments but on most game at long range the difference between the two bullets will be very slight when a vital impact is scored.

    For a dedicated long range elk rifle I would agree full well, the larger calibers will perform better but that is not to say there would be anything to complain about using the 200 gr ULD RBBT 7mm bullet either.

    No flaming or fighting going on here or intended, just good discussions on an interesting topic. I love both the 7mm and 338 calibers and both are extremely deadly on game at any range to be honest. Just have to hit them right with either caliber!! /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)
     
  10. davewilson

    davewilson Well-Known Member

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    Re: Comments on HOT 7mm\'s

    Kirby, i understand what you're saying, i just don't agree with you. i never said the 33 was balistically better than a 7.i said it hits harder.i also never said the big seven's with the 180 or 200's weren't plenty for elk. they are.to be honest i think the 300/338 is balistically better as well.i've seen your numbers on the BC of the 200 and based on my testing,find them very high.i'm not going to debate this subject but my results show the 300 to have a better BC.

    my point was "hits harder" when you're talking elk,you can't hit em too hard.you're arguing a 200 gr .28 dia bullet against a 300 gr .33. yes, both will do the job. but so will a .24 105 gr bullet.but it won't hit as hard will it.

    i agree both will handle the job with an accurate hit, especially from 6-800.but for hunting elk out to 800 yards, or any range for that matter.a 33 is head and shoulders above a 7.
     
  11. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Re: Comments on HOT 7mm\'s

    Dave,

    Point taken and I agree, elk are big, strong, hard to kill critters! Never hurts to hit them with a large diameter bullet with alot of weight to it!!!

    Fully agree!!

    Good Shooting!!

    Kirby Allen(50)
     
  12. lerch

    lerch <strong>SPONSOR</strong>

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    Re: Comments on HOT 7mm\'s

    The only thing I am not following here is that at one point you say "i never said the 33 was balistically better than a 7."

    A sentence or two later you say "to be honest i think the 300/338 is balistically better as well" Isnt this a direct contradiction. I am not trying to start anything with this but it just doesnt make sense to me how a bullet with a bc of .810 can be "ballistically" better than a bullet with a bc of .910

    If you dont believe the BC of the 200 WC to be .910 then that is fine, though I think SS7MM has done plenty to prove it.

    Just trying to get my bearings on this converstation.

    steve
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Re: Comments on HOT 7mm\'s

    Leaving BC out of this, I can tell you for a fact that a 7mm 200 gr ULD RBBT launched at 3100 fps has less bullet drop then a 300 gr 338 SMK launched at the same speed.

    A 240 gr 308 SMK is not really in the same class of either of these bullets as far as bullet drop for equal velocity is concerned.

    That said, on game performance will be more dramatic the larger the bullet is that you drive into your target, this is mainly a result of bullet diameter more then anything. As far as effectively killing a big game animal, put all three through the vitals at any supersonic velocity and you will have a dead critter.

    I think Dave was talking in reference to the on game visual impact more then anything. The big 338s certainly are impressive. I do not see much difference between the 300 RUM which I hunted with for many years and my 7mm AM except that the 7mm makes it look silly ballistically.

    TO be fair I was using a 180 gr Ballistic Silvertip in the 300 RUM but it was loaded to 3400 fps as well!!

    This is not worth an arguement of any kind. In the right hands they are all more then powerful enough to kill any critters we point them at.

    Kirby Allen(50)
     
  14. davewilson

    davewilson Well-Known Member

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    Re: Comments on HOT 7mm\'s

    Lerch,i was just trying to clarify what i said in my original statement, that was i didn't say it was ballistically superior,i said it hits harder. but i do believe the 300 is superior to the 200 ballistically.you're also right,i don't think the 200's have a BC of .9.

    i also agree it's a moot point,either bullet when feed ribs,will make a mess of a fryin pan!