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Thread: Bullet energy and penetration

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    Member martentrapper's Avatar
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    Default Bullet energy and penetration

    With my kid holding a Delta Bison tag, I'm wondering about the 200 gr. bullet with minimum 100 yd energy of 2000 ft/lbs. Cruising various internet sources, quite a few bullets, even down to 150 gr. can produce 100 yd energies of 2000 ft/lbs.
    I'm curious if a 200 gr. bullet hitting an animal with a certain energy at a certain distance will penetrate farther than a smaller bullet at the same energy and distance?
    Thanks
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    Member GrassLakeRon's Avatar
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    Quote Originally Posted by martentrapper View Post
    With my kid holding a Delta Bison tag, I'm wondering about the 200 gr. bullet with minimum 100 yd energy of 2000 ft/lbs. Cruising various internet sources, quite a few bullets, even down to 150 gr. can produce 100 yd energies of 2000 ft/lbs.
    I'm curious if a 200 gr. bullet hitting an animal with a certain energy at a certain distance will penetrate farther than a smaller bullet at the same energy and distance?
    Thanks
    I have seen strange things when hunting different animals. My rule of thumb is bigger diameter bullet at a 2000 fps or better upon impact with large animals. My buddy shot one in north dakota with his 45-70 using buffalo bore ammo....it still turned and ran at him before dying 40 yards away. Just food for thought.

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    Member hodgeman's Avatar
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    Lighter bullets need higher velocity to achieve the same energy numbers. The problem with velocity is that it's not fixed like mass....simply put a light bullet will slow down before a heavy bullet gets lighter.

    Heavy for caliber bullets at moderate velocity trump everything else when penetration is the name of the game. My buddy shot his Bison with a .30-06/ 220 at something like 2300fps and it went clear through. A 150gr at 3000fps....probably wouldn't make it.
    "I do not deal in hypotheticals. The world, as it is, is vexing enough..." Col. Stonehill, True Grit

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    Heavies are often more heavily built, leading to less deformation and aiding penetration. A light bullet that disrupts more isn't going to penetrate all that far, in spite of the high vel.

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    Member Matt's Avatar
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    Quote Originally Posted by hodgeman View Post
    Lighter bullets need higher velocity to achieve the same energy numbers. The problem with velocity is that it's not fixed like mass....simply put a light bullet will slow down before a heavy bullet gets lighter.

    Heavy for caliber bullets at moderate velocity trump everything else when penetration is the name of the game. My buddy shot his Bison with a .30-06/ 220 at something like 2300fps and it went clear through. A 150gr at 3000fps....probably wouldn't make it.
    How about that 220gr Partition at 3000 fps? I got the same tag and was thinking about this bullet since I can't get the 200gr TSX to shoot.

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    Member hodgeman's Avatar
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    Quote Originally Posted by Matt View Post
    How about that 220gr Partition at 3000 fps? I got the same tag and was thinking about this bullet since I can't get the 200gr TSX to shoot.
    It would likely do, not sure it will out penetrate the 220 RN going a bit slower. The front part of the Partition at high impact velocity will expand violently, might sheer off, and the lighter rear portion will continue. Will it make it clean through? Probably would I'd think. Dead bison if whacked in the pump room? Almost certainly.

    That's gotta be a .300 Weatherby or a RUM to get a 220 going that fast. You might also consider a Woodleigh Weldcore.

    If you get to start later in the year, expect longer range shooting than the early season.
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    Member marshall's Avatar
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    Quote Originally Posted by Matt View Post
    How about that 220gr Partition at 3000 fps? I got the same tag and was thinking about this bullet since I can't get the 200gr TSX to shoot.
    Matt, higher weight within the same caliber will have a higher sectional density. In simple terms this gives it more penetration than lighter, faster bullets of the same caliber. Bullet construction and operation within design speeds are important too.

    I'm assuming you are shooting a 300RUM or other large case magnum with your question? There is no way to safely push a 30-06 shooting 220gr bullets at 3000fps.

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    Quote Originally Posted by Matt View Post
    How about that 220gr Partition at 3000 fps? I got the same tag and was thinking about this bullet since I can't get the 200gr TSX to shoot.
    It has got to be the RUM.

    I never got a 200g TSX to shoot out of my RUM's either. The 220g partition was ok, slightly better accuracy than the 200g tsx. Really, at 3000+ fps, shoot most any well constructed bullet and you will do fine. 180g or more ttsx, tsx, etip, partition, A-Frame.......

    What is your kid shooting? How old is he/she?

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    Responding only to subscribe - I love a good ballistics discussion.

    The other 299,300,000 people can have it.

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    Sorry for the confusion guys, but yes, it's a Model 70 300 RUM with a 26" fluted, #3 pac-nor barrel.

    And hodgeman, thanks for the heads up on the longer range part. And wind I'd imagine, too?

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    Member hodgeman's Avatar
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    Quote Originally Posted by Matt View Post
    Sorry for the confusion guys, but yes, it's a Model 70 300 RUM with a 26" fluted, #3 pac-nor barrel.

    And hodgeman, thanks for the heads up on the longer range part. And wind I'd imagine, too?
    Yep, wind too. You might consider the 200gr AB- slightly flatter trajectory, plenty tough, little better wind resistance. Not really enough to matter perhaps but the AB has become my go to bullet in nearly everything. They have a new 210gr Long Range AB that might be perfect in the RUM. Haven't played with them yet but several have folks I know have and they like them.
    "I do not deal in hypotheticals. The world, as it is, is vexing enough..." Col. Stonehill, True Grit

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    Momentum! That is what a heavy bullet has and a light bullet lacks. Remember, an object in motion tends to want to stay in motion, so the greater the mass of an object the greater the tendency to stay in motion. Momentum!

    I shot a moose in 2010 with my .58cal muzzle loader. I used a patched round ball weighing 282 grains over 90 grains of RS, according to my book it moves 1175 FPS/MV and has 1073 FTLBS at 100 yards( I never put it over the chronograph). The estimated range when I shot that moose was 50 yds+-, the ball traveled through 30" of moose (no bones were struck) and the ball looked like it could be fired again due to lack of deformation. It was an eye opening example of momentum.

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    Quote Originally Posted by .338WM View Post
    Momentum! That is what a heavy bullet has and a light bullet lacks. Remember, an object in motion tends to want to stay in motion, so the greater the mass of an object the greater the tendency to stay in motion. Momentum!
    This is exactly right. Momentum is much better at determining penetration potential than energy. I would definitely choose a heavy for cal bullet to shoot a bison with.

    As for type of bullet, at close range, inside 100 yds I would choose a GSC FN type bullet for large and dangerous game. Blunt nose projectiles will cause more wound cavitation than expanding rounded mushroom projectiles, i.e., flat nose hard cast bullets.

    You might find this interesting reading...

    http://www.gsgroup.co.za/03fn.html

    It's probably a little late to get these for this year's hunt but not a bad idea to have some around for future hunts. It is what I would use for close range coastal bears in the 338 or 375 cals.

    For your daughter's hunt I would go with the 180 E-Tips. They expand to a fairly flat frontal. Assuming your using a 30-06 they should look something like this inside of 100 yds. These were recovered behind targets at 400 and 500 yds shot form a 300 RUM @ 34400 fps.



    The 200 gr Nosler Partitons should work fine as well, I just like the E-Tips a little better.
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    Quote Originally Posted by MontanaRifleman View Post





    For your daughter's hunt I would go with the 180 E-Tips. They expand to a fairly flat frontal. Assuming your using a 30-06 they should look something like this inside of 100 yds. These were recovered behind targets at 400 and 500 yds shot form a 300 RUM @ 34400 fps.

    The minimum bullet weight for Bison is 200 grains ( http://www.adfg.alaska.gov/index.cfm...abison.weapons ). I like Partitions because they function over a wide range of conditions and they would work OK for Bison but they wouldn't be my first choice. If I was the OP I'd probably choose something like an Accubond or Swift A-Frame. The Partition could lose a lot of weight fast if it hits heavy bone.

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    Without resorting to a ballistic table to verify, my strongest recollection is that the minimum was originally selected to meet the capabilities of a 30-06 with heavy bullets. If that's the case, almost anything with a comparable or larger case could be loaded down for a youngster to meet the requirement.

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    Quote Originally Posted by Meanderthal View Post
    The minimum bullet weight for Bison is 200 grains ( http://www.adfg.alaska.gov/index.cfm...abison.weapons ). I like Partitions because they function over a wide range of conditions and they would work OK for Bison but they wouldn't be my first choice. If I was the OP I'd probably choose something like an Accubond or Swift A-Frame. The Partition could lose a lot of weight fast if it hits heavy bone.
    I think the A-Frame would be a great choice, but I think the Partition would be better than the Accubond. I had a 180 AB just come apart on me when it hit the spine of a cow elk at about 150-200 yds out of 300 WSM @ 3000fps MV. If the 200 Partition loses it's nose, that's not all bad... a blunt frontal will do a lot of damage. For a rib shot, I would use a 210 Berger. It would turn the lungs into jello, and usually with Bison you can pick your shot.
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    240 grain Woodleigh Protected Point would penetrate like a torpedo. At 2250 it would be perfect. Just my opinion.
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    Member martentrapper's Avatar
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    Yes, have to use a 200 gr. at minimum. Was planning on 30-06 but the Rem 7400 we got does not shoot well. Somewhat up in the air as to what we will use for this hunt.
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    Quote Originally Posted by martentrapper View Post
    With my kid holding a Delta Bison tag, I'm wondering about the 200 gr. bullet with minimum 100 yd energy of 2000 ft/lbs. Cruising various internet sources, quite a few bullets, even down to 150 gr. can produce 100 yd energies of 2000 ft/lbs.
    I'm curious if a 200 gr. bullet hitting an animal with a certain energy at a certain distance will penetrate farther than a smaller bullet at the same energy and distance?
    Thanks
    Yes. A lighter bullet will penetrate less than the heavier bullet at the same energy and distance. Of course, we're assuming the bullets are of similar construction (e.g. not equating penetration of 180 grains of rubber to a 180 grains of solid copper).

    Congrats on the tag. If I had the tag, I'd go with a >200 gr bullet that retained the 2000 ft/lbs at 100 yards.

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    Quote Originally Posted by martentrapper View Post
    Yes, have to use a 200 gr. at minimum. Was planning on 30-06 but the Rem 7400 we got does not shoot well. Somewhat up in the air as to what we will use for this hunt.
    BTW - I recently picked up some 200 gr accubonds, and could load some up for you in 30-06 .. if that would help.

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