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Old 09-27-2009, 09:08 PM   #11
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Apples and oranges...your comparing a premium Accu-tip boat tailed bullet with a BC of .447 starting out at a higher muzzle velocity, to a 30-30 styled round nose bullet with a BC of .261 and going slower. If you want accurate ballistics check the Sierra Rifle Reloading Manual...that's where I get my information from. It has pages of ballistics data compiled for various muzzle velocities using the SAME Sierra bullet design starting out at the same muzzle velocities. The data I quoted above was based on a 2800 FPS MV using a 130gr. and 150gr. Sierra SBT. All things being equal, the laws of physics tell you that a heavier projectile will retain more energy than a lighter projectile going the same speed. That's what the formula for Kinetic Energy states - increase one variable (mass or velocity) and the KE increases.

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Old 09-27-2009, 09:14 PM   #12
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Here is a little closer comparison between a 130 and 140 gr (not exact tho)

http://www.remington.com/products/ammunition/ballistics/comparative_ballistics_results.aspx?data=R270W2*RS 270WA

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Old 09-27-2009, 09:28 PM   #13
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Quote:
Originally Posted by davemccarthy707 View Post
Here is a little closer comparison between a 130 and 140 gr (not exact tho)

Remington.com - Products - Ammunition - Ballistics

I don't get it...are you disputing the KE equation? Or are you saying that Remington found a way to change the laws of physics? The ballistics data you posted from Remington are a lot closer because the BC is much closer - but the 130gr. is still being driven at 135fps faster than the 140gr., which accounts for the similarities in energy and drop. Given the choice between a manufacturer's stated ballistics for a cartridge they manufacture, and a physical law, I would have to choose the laws of physics...I mentioned the Sierra Manual because it backs-up my assertion as well as the KE formula...I don't know what Remington is putting out there, but even using the simpler equation for energy E=MV, it should be obvious that increasing either M(mass) or V(velocity) yields a higher E (energy)...having attended the NAtional Matches at Camp Perry I can state unequivicably that a 165gr. Match bullet retains more energy and drops less at 1000 yds. than does the exact same bullet in the 150gr. weight. It may only be a difference of an inch or so in drop and a couple hundred ft. lbs. of energy, but this validates what physics has been teaching us for a very long time! The is much less disparity among .270 bullets because generally they have a higher BC than the .30 cal. bullets. In fact the 6.5mm (.264) bullets have some of the highest BC of all, and this is why bench rest shooters use them.
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Old 09-27-2009, 09:38 PM   #14
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I am not disputing the KE equation. However all things being equal the 130 grain bullet will have higher velocity from the get go. If you are using 2 identical cartridges the lighter 130 gr bullet will have a higher velocity as there is less mass to put in motion.
I think this is where remington is getting their numbers. If you have the same velocity then the heavier bullet will have more impact force as per the KE equation as you have stated.

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Old 09-27-2009, 10:02 PM   #15
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I think this is where remington is getting their numbers. If you have the same velocity then the heavier bullet will have more impact force as per the KE equation as you have stated.

This is correct and I think this is where the misunderstanding is. I am not using Factory ammo data. I am using the Sierra Loading Manual, where muzzle velocity can be varied according to the handloaders' desired results. The ballistics tables data are based on muzzle velocities and bullets of similar BC's. For example, they list several pages of data for 130gr. SBT Sierral bullets ranging from 2300 to 3400 fps. The also list several pages of data for all other weight bullets (90, 110, 140 & 150gr). The method of comparison I am using is comparing a 130gr. SBT travelling at 2800 fps. and a 150gr. SBT also going 2800 fps.. In this case, KE is considerable greater for the heavier bullet, as the KE equation bears out. There are so many variables to consider when calculating ballistics that it is mind boggling. Atmospheric conditions play a huge part, and because of this, no one should expect to get the same results as posted either by the manufacturer or by the reloading manuals - they are just a guideline.
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Old 09-27-2009, 10:19 PM   #16
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Right on. I knew there was a little bit of misunderstanding there on both our parts.

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Old 09-27-2009, 10:37 PM   #17
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Quote:
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Right on. I knew there was a little bit of misunderstanding there on both our parts.
I'd still choose the heavier bullet for elk!
I don't buy factory ammo either...except to get the brass to reload.
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Old 09-27-2009, 10:51 PM   #18
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Unfortunately here I have no choice. It costs me 2.50 everytime I touch the trigger on my .300 magnum

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Old 09-27-2009, 11:41 PM   #19
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One thing to always remember is that we as hunters have the responesability to affect the quickest most humane end to a noble animal. When we start using bullets not designed for the species we are hunting then we are doing a great disservice to the animal and our sport. I am a student of terminal ballistics and have in my collection nearly 200 bullets recovered from animals. I have autopsied long dead and stinking animals to see the cause of the unrecovered animal. I have come to some personal conclusions that I will share with this forum. I absolutely detest any boattail bullet for big game, Rem core-lokt are poor performers (shot a mule deer last year with a 130 core-loct from a 270 Win got only 4" of penatration before the bullet blew up). Also I have had very poor luck with Sierra on big game they were way to fragile. One note I quit guiding before the newer bonded core arrived on the market and the few I have seen pulled out of game seem plenty adequate so far. I know everybody has a story with their favorite this or that however few hunters analize their trophys or remember their failures. Most often if it is a failure the animal rums off to die a slow death without the hunters knowledge as to what happened. Just my 2 cents worth.

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Old 09-27-2009, 11:59 PM   #20
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Interesting...I strictly use remington core-lokt in my .300 magnum. What would you suggest is a better performer. I have also tried those cheap winchester in the solid grey box (can't remember) These are the only 2 kinds wally world sells around here. Maybe a Federal type?

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