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Impact Velocity and Impact Energy

 
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  #1  
Old 02-15-2013, 07:25 PM
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Location: Laramie, WY
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Impact Velocity and Impact Energy

Hi All,

I've been kicking around getting into the bigger class of cartridges such as the big 338's or even into the 375's. I've been solely looking at impact energy as a comparison and figured it'd be capable on elk as long as I maintained 2000 ft/lbs or so. Obviously shot placement is key but I'm speaking about what the round can physically accomplish.

But then I realized that bullet expansion is dependent on impact velocity. I've read that 1800 fps is a general minimum. With that in mind something like a 338 Lapua is dripping below that at something like 800-900 yards while carrying 2000 ft/lbs to more like 1200 yards. Something like the 375 Rum and a 350 gr SMK carries the energy to 1500+ yards but drops the velocity at around 1000 yards.

So my question is this: Given a proper bullet, what criteria it meet to be physically capable on elk sized game at distance? Is it solely a function of impact velocity or energy?

Thanks all and God bless you,

Adam
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  #2  
Old 02-15-2013, 08:10 PM
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Location: Boise IDAHO
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Re: Impact Velocity and Impact Energy

Not necessarily energy and velocity only. Long range bullets are typically very long and destabilize quickly in flesh at low velocities. A 1.8" long bullet flipping end over end at 1500 fps still does a lot of damage. I shoot some long range bullets deliberately subsonic and still get pretty decent damage from them.
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  #3  
Old 02-15-2013, 09:20 PM
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Join Date: Apr 2012
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Re: Impact Velocity and Impact Energy

Their not gophers you don't need to turn em inside out to kill them, just put the bullet where it belongs and they die. With anything heavier than 160gr I look at retained velocity only, stay above what the manf suggests as min velocity and your fine.
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Keep in mind the animals we shoot for food and display are not bullet proof. Contrary to popular belief, they bleed and die just like they did a hundred years ago. Being competent with a given rifle is far more important than impressive ballistics and poor shootability. High velocity misses never put a steak in the freezer.

Joe
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Old 02-16-2013, 12:03 AM
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Re: Impact Velocity and Impact Energy

There was a post on here of a bull shot at 1300-1400.with a 338 edge.Which to me sounds very reasonable.The long range pursuit just showed a kill my a young kid at 1200 with a 7rm.I think that is WAY pushing it for a 7rm. I hung mine up 20+ years ago,after a loss.Went to a 340 wby,and it blows the 7 away for knock down. I shot 225 out of it.Now use a 338 w/300 gr.and that is a step up also.Unless you use them,there is no comparison in a 7mm ,to a large 338 with a 300 gr. I t is usually 1/2 the weight bullet.The holes I have put in game with the 300 gr.are gruesome
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Old 02-16-2013, 12:15 AM
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Re: Impact Velocity and Impact Energy

Quote:
Originally Posted by sp6x6 View Post
There was a post on here of a bull shot at 1300-1400.with a 338 edge.Which to me sounds very reasonable.The long range pursuit just showed a kill my a young kid at 1200 with a 7rm.I think that is WAY pushing it for a 7rm. I hung mine up 20+ years ago,after a loss.Went to a 340 wby,and it blows the 7 away for knock down. I shot 225 out of it.Now use a 338 w/300 gr.and that is a step up also.Unless you use them,there is no comparison in a 7mm ,to a large 338 with a 300 gr. I t is usually 1/2 the weight bullet.The holes I have put in game with the 300 gr.are gruesome
+1
Sectional Density & Momentum are big factors.
Just like BC, Bullet Construction, & Muzzle Velocity, the SD, & Momentum ARE important parts of the equation.
Bigger is better the farther you reach.
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  #6  
Old 02-16-2013, 10:10 PM
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Re: Impact Velocity and Impact Energy

Cow boy....I think you are on the right track and doing your homework on this subject. Both are important for the reasons you list. If you do error, bigger is better but you can do a lot with a 30 that shoots a bullet with a high b.c. and expands at low velocity. This is why I started making my own bullets several years back. I shoot a 30/375 S.I. that shoots my 208 SXR at around 3050' with a G1 b.c. of .345. The bullet will expand down to around 1200/sec and I feel it will do the trick on elk to 1500-1600 yards......Rich
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