Sectional density and BC

[BUSTINDOGS]

Lets say that without knowing the diameter or weight of the bullet, or what the cartridge is that we launch them from, which one would kill better. Better being faster?

Example #1 Sectional Density of .287 BC of .490 starting out at 2900 fps

Example #2 Sectional Density of .283 BC of .475 starting out at 2900 fps

I will add the cartridges in after a few replies. I basically am at the point where i need to re-barrel a rifle soon and cant decide weather i should stick with what i have or change to something different.

 

[Mikecr]

This comes down to attributes of terminal ballistics for the specific bullets.
IMO, tying terminal performance to SD alone would be precarious at best.

 

[Hand Skills]

Agree, both points are moot when discussing expanding bullets which by definition DEFORM on impact.

Solids or Hard cast, maybe even FMJ's (bullets that don't change shape when they hit flesh and blood) could warrant a discussion, but even then the difference between .283 and .287 is on the order of 1%

 

[BUSTINDOGS]

Both bullets are Nosler partitions and of different caliber... With that said no one would expect an elk to be any less or more dead if hit by one or other?

 

[Mikecr]

I'm definitely not a terminal ballistics expert, but in my consideration:
Sectional Density: A bullet's weight in pounds divided by the square of its diameter in inches." Note that SD is independent of a bullet's shape. All bullets of the same caliber and weight will have the same SD, regardless of their shape or composition.
So for similar SD from different cal bullets, the weights must be different.

Different weights at same speed produce different knockdown energies.
Same build, SD, and velocity, but different cal and energy, affects penetration.
Many believe the point of impact and construction are primary to all else.
I personally believe the most powerful of ALL ballistic attributes is accuracy.

So I would choose a bullet known to be sufficient, while providing the most lethal point of impact(best accuracy) for a given system, and sleep well with this.
I've dropped whitetail deer so fast they still don't know they're dead, at over 500yds, with flat base 40gr 22cal thin-skinned BR bullets. Brain shots
Would that work with Elk? At ~100yds, yes. No problem.

 

[BUSTINDOGS]

Does energy (if similar) have a great effect on killing and penetration? I thought that SD and velocity would dictate how well two bullets of the same design could penetrate.

I have been having a struggle within myself to decide weather to re-barrel my 6.5-284 into a 280 Remington or keep going with the 6.5-284...
My 6.5-284 shoots a 140 at a very accurate 2920 fps.
I want a short barreled (24") handier rifle. I really like the standard .280 Remington pushing a 160 partition for a deer/elk gun.

Me really wanting the 280, but trying to justify it. Got me thinking my 6.5 pushing a 140 a little faster than a 280 will push a 160 should be every bit as good of a killer as the 280... why not? The only thing the 280 really has over the 6.5 is the bullet being .020 bigger around... right?

I've killed deer and elk with the 6.5-284, but would the 280 kill faster, with more authority?

300 yard figures

6.5-284 140 partition @ 2920 muzzle
2366 retained velocity
1741 retained energy

.280 Remington 160 partition @ 2850 muzzle
2275 retained velocity
1839 retained energy


This is a hunting/carry gun. I have a big, heavy, long barreled 7mm SAUM that takes care of the long stuff.

 

[Mikecr]

Which path will be most accurate in the long run?
If honestly both the same, It looks like a wash to me.

 

[HARPERC]

In the class of cartridge you're describing not enough difference to talk about, or probably measure. A larger jump might be arguable, but not with what I've seen described here.