sectional density & stopping power ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by winmag, Jan 14, 2012.

  1. winmag

    winmag Well-Known Member

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    So how much does Sectional density come into play when it comes to delivering energy on target?

    Specifically a 277 cal 160gr Partition has an S.D. of .298
    A 30 cal 165gr partition has an S.D. of .248
    (Just for referance, for a 30 cal bullet to get an S.D. of 290ish its gotta weigh about 190gr)
    So if a 160gr bullet is launched out of my 270wsm @ about 2850
    & a 165gr bullet is launched out of my 30-06 @ about 2850, wich bullet has more potential for laying the smack down on "X" critter?
    The 5 grain heavier 30, or the higher s.d. 270?

    I ask this, Not to start any arguements, but to help me decide wich Cal/cartrige to buy next. I already have a Model-70, 270 wsm with an unbelivably scary accurate 140 Accubond load. I'm not gonna swich from it.
    I already have an -06 that I shoot 165's & 180's out of. Plus, I just parted company with my 300 Wby, cause I'm REALLY wanting a 300 wsm for the simple fact that its Very high performance for very little cost. (60ish gr of powder vs 80ish, less expensive brass etc over the Wby) for 5-600yds on Bear, & Elk sized critters.
    Then someone just HAD to post a BLR in 270 wsm in the classifides, & it got me wondering...... Why not have two 270 wsm's. One for deer & smaller critters with the 140's, & one for Elk,& bear with the 160's out to 5-600 yds..... So now I have a moral delima. I'm a 277, & 30 cal freak, & personally have no use for 7mm's so if we could avoid that whole topic that would be nice. (no offence meant guys, its just a personal preferance thing)
    In the end ill probably end up with the 300 wsm in another Model-70 Winchester, cause that's just me. But it does make for an interesting technical discussion.
    What say you....?
     
  2. Senderofan

    Senderofan Well-Known Member

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    Here's some light reading that may offer you some help...or at least...offer you some scientific criteria in selecting your next round.

    Terminal Ballistics

    Wayne
     

  3. Senderofan

    Senderofan Well-Known Member

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    If you scroll down the study a fair bit...you'll see several .308 rounds compared...it is interesting that the 180 gr. Swift A-Frame in the .30-06, outperforms the .300 WM 200 gr. Swift A-Frame. It appears that bullet design / construction has a lot to do with terminal performance versus bore size and/or speed. The caveat being....it appears that the .375 H&H magnum had the best penetration performance of the rounds tested.

    Perhaps the .375 Ruger might be just what fills your need....this is a very interesting round, if you want to keep your rifle in the .30-06 length:

    Hornady & Ruger Take On The .375

    Wayne
     
  4. winmag

    winmag Well-Known Member

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    Ohhh my head hurts now.... But that was informative for sure. Results were not exactly what I thought they would be. But in some cases very simmilar. Hmmm. Much to ponder...
     
  5. HARPERC

    HARPERC Well-Known Member

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    My thoughts for what their worth:
    I like SD within it's limits. I believe it's a good indicator to predict penetration in similar bullets, in similar situations. I don't own a 270 I'd use the 160, When I shoot my 30 calibers I like bullets 200 and up. My experience I prefer SD's of about .3.
    Energy, momentum or something is a factor in lethality, but the variables will always make this elusive to establish. In addition it would take a pretty good number of controlled kills to be conclusive.
    My first experiences were with a 30-06. It came with factory Remington 220 RN. I also got a can of surplus military AP ammo. Both would penetrate, both were lethal, but to my eye the 220 expanding was more "decisive". The statute of limitations is past, but I won't boor you with details, of why I don't like the "harder" type bullets.
    SD of expanding bullets change on impact, with the newer bonded bullets it's often advised to use a step lighter than usual. I feel with that larger frontal area maintained a step heavier is a better way to go. Example the old 210 338 Partitions in my experience out penetrate the 225 Accubond. I've never seen a deer stop the 210, but have recovered the 225. We shot the 30 caliber 180 Scirrocco into a lot of old inedible hog meat and bone. We could never destroy one, but we could never get much penetration either. It proved so in the field as well. In the choice you are making I believe the 160 .270 will out penetrate the 165 .30 which in my mind makes it a better choice.
    Wound channels are both width and length, exit holes are good. If I was going to shoot 160 bullets the 270 is what I'd pick. 180 in 7mm, and 200 up in 30, and so on. Bryan Litz has a pretty good article on why heavier 30 caliber bullets, or something like it.
    I know this will be a Taste Great, Less Filling kind of thread, but that's my 2 cents.
     
  6. winmag

    winmag Well-Known Member

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    Oh, I'm not building anything, I'm simply adding to the collection.
    Ill keep my -06, & my 270wsm, & add another rifle, most likely a 300wsm, to the bunch.
    It may not be a 1k Elk hammer, but certainly good enough for 5-600 yds. wich is this next rifles intended use.
    Someday, when I have $ again I'm going to start talking seriously to the great sponsors & smiths here at LRH for a 300RUM build, or an Edge build, But untill I have cash in hand, I'm gonna have to make the most of what I have.
     
  7. Senderofan

    Senderofan Well-Known Member

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    I'm having my "Elk Hammer" being built right now. I have a long action Remington Sendero being converted to a .338 Sin. It really isn't a huge money pit....and the round is designed to fit in most long action rifle magazines. It is designed for 225-250gr. bullets in a 26" barrel. Which seems to be plenty medicine for any North American game at the ranges you list. And perform nearly as well as a .338 Edge....but with better brass and slightly less powder.

    Good Luck with your quest...Many have / or are on a similar one.

    Wayne
     
  8. Beng

    Beng Well-Known Member

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    Hi winmag.
    To kill / stop an animal you got to hinder its central nervous system from working.
    This can be achieved by hitting the CNS directly, or cutting its oxygen supply.
    The latter can be achieved by either hitting the heart or by blood loss.
    Brain and heart are tiny targets at long ranges, thus i would recommend killing by blood loss.

    The more blood the animal looses, the earlier it will sucumb to its wounds.
    The more tissue damage you inflict in an highly circulated body part, the greater the bloodloss over time will be. Especially when the heart isn't damaged.

    Necessary condition for high blood loss is penetration into an area with high blood circulation, this will be the torso with lungs, liver and a high density of arteries and veines.
    Hitting both lungs and exiting has the nice side effect of hindering the animals respiration and thus stopping the cns' oxygen supply.

    Sectional density affects penetration, the heavier a bullet (design and caliber given) is, the deeper it will penetrate.
    This effect can be achieved also by using bullets of a more rugged design, though this will usualy compromise tissue damage.
    The bigger the bullets diameter, the more tissue damage you will inflict.
    More Energy to work with, more fragments &c

    Conclusion:
    Choosing a potent catridge, which is able to accelerate a heavy for caliber bullet at least to standard speeds (~2700 fps muzzle velocity I guess) will allow you to choose bullets of less rugged design which will penetrate deeply and do more damage by fragmenting, than sturdier bullets would do.
    The faster your bullet travels at impact the higher the stresses inflicted on the bullet will be and the sturdier its design has to be to ensure deep penetration instead of surface fragmentation.

    With more rugged design I mean for example:
    Hornady DGS > Barnes TSX > unbonded softpoint > varmint bullet.

    For optimum stopping power choose a catridge that delivers your bullet at
    2000 - 2200 fps terminal velocity for your choosen maximum range.
    Then choose a proven hunting bullet with sufficient bc to achieve this velocity and sufficient accuracy in your gun.
    Last but not least your catridge should be appropriate for the heaviest game you will hunt with this gun.
    For Roe deer a 6,5x47 is quite appropriate, for hogs or wisent more potent catridges have to be choosen.

    As you already own catridges appropriate for medium game, I would recommend something heavier.
    A .338" or even a .375" caliber perhaps?
    There is a german .375 catridge based on the .338 Lapua I'm quite interested in.
    Afair Kirby Allen got something similar and as you live in Wildcatters paradies, other gunsmiths will propably offer similar catridges too.

    ps: did some spelling corrections
    pps: I didn't read most of the replies, when I started writing this just 2 replies were posted.
    ppps: I like your terminal ballistic link senderofan.
     
    Last edited: Jan 14, 2012
  9. winmag

    winmag Well-Known Member

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    Sorry, I forgot to mention I already have a 338 too.
    I have enough guns for what I intend to do, I was more trying to talk myself into/out of another 270 wsm in a configuration I don't already have, vs another Winchester Model-70 in 300 wsm. To fill the gap between my big guns, & my lil guns in an economical way vs horsepower alone to launch bigger sluggs. I sold my 300wby because of the expense involved in shooting it. Not because I thought I could out perform it. I can't with a wsm. I just limmited my range to what I feel is still quite enough to smoke an Elk & then some.
    I will get another wsm. I just saw a sexy BLR, & wanted somebody to tell me I was a dreamer, & needed to stick with the origional plan of the 300wsm vs the sexy BLR, because the dif between my -06 & 270wsm was negligable, & bigger is better.
    But I am still curious wi h is more effective between the two.....
    In comparing my -06 to my 270 wsm with simmilar wt. partitions, at simmilar speed, I was trying for some insight as to are they more or less the same or does one have a clear advantage due to S.D. alone.
    Sorry for any confusion.
     
  10. Beng

    Beng Well-Known Member

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    Sorry I didnt understand that in your first post, got to do with english not beeing my native language.

    You can shoot (custom) bullets with higher sd and thus most propably higher bc out of your .270 wsm with a given velocity compared to your .30-06.
    It should outperform a .300 wsm too, considering sd and bc at a given velocity.

    Talking you into buying a new gun is nice, the more rifles one got the better :D
    Why dont try something in the .338-06 or .338 wsm range?

    And btw what is a blr?
     
  11. Senderofan

    Senderofan Well-Known Member

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    I think he means "BLR" as in Browning Lever Rifle:


    Browning BLR - Wikipedia, the free encyclopedia

    Browning BLR Rifles

    Browning BLR RiflesĀ Firearms
     
  12. Senderofan

    Senderofan Well-Known Member

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    Guess if it was a BLR in .325 WSM.....I wouldn't hold you back for your Elk pursuits.
     
  13. liltank

    liltank Well-Known Member

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    300WSM with the following bullets:

    185, 190, 200, 210/15 Berger

    200 Sierra Game King

    180 Speer Deep Curl
    180/200 Speer Hot-Cor

    180 Scirrocco

    180+ Hornady SST/Interbond

    These will get all you need to 800+ yards with the speeds you can push it with a WSM.

    Tank

    PS- Unless you want to use a laser, then go with the 165-175 grain bullets. Still good to 800!
     
  14. bigngreen

    bigngreen Well-Known Member

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    I saw that BLR also, I've quit looking at 270 WSM's in the classifieds as it causes me issues.

    Comparing the 160 class bullets from the 270 WSM to the 30-06 is kinda unfair to the old dirty aught six. You really should be able to push them up around 3000+fps easy in the 270 WSM anyway.
    I like SD to drive bullets deep into elk but I like it in proportion to the strength of the bullet, the Matrix is a perfect example, the 165 has an SD of .307 and while it opens up easily it has the SD to drive that violence deep into the center of the game. Shooting the 140's with an SD in down around the .260's and the Accubond starts looking better, relying more on construction to get that bullet deep.

    Some one needs to build you a sexy long range rifle for shooting some of the 175 Matrix in the 3000 fps range, it's just about orgasmic for a 270 guy!!! gun)