Caliber selection

[sbtennex]

Originally Posted by chuck

SD means nothing, energy means less, and bullet construction means everything.

Only partially true at best. Bullet construction is an important choice obviously, match the bullet to the game, but high SD at hunting velocities requires larger calibers to obtain that high SD. High SD means penetration so SD in the overall picture means everything. I shoot deer once in a while with my .243 and 85 gr TSX's from Barnes who says himself "forget ft/lbs.." For 150 lb deer okay, but the low SD rules it out for big fast and probably fast moving bucks - and you can't argue the construction other than the simple fact that it AIN'T ENOUGH GUN. Not enough SD and certainly shy on the energy which IS important. BTW, if SD means nothing, energy can't mean less........what's less than nothing? And just FTR my pack everywhere just in case rifle is a $200 tuned Stevens 7-08 wearing a $900 Zeiss and shooting 120 TTSX's at 3000 fps.

Sectional density (SD) is an outdated term that was originally applied to non-jacketed bullets. It today's world of controlled expansion bullets, SD really does mean nothing. It is no indication of penetration unless it's used to compare bullets of identical construction. When you start comparing two different bullets, SD means nothing. Scares me that I agree with Chuck.

But I agree that energy can't mean less..... Energy can actually mean a lot. It just depends what work you are equating to that energy.

[Stinky Coyote]

I agree with chuck on most points also. Have seen a ewe at 530 yrds with 180 AB's out of 300wm first hand and a wt doe at 521 yrds with .270 and 130 gr fusions first hand and the difference was remarkable....so on that point i dissagree...both modern bonded (intended for deer so to speak) type bullets but the damage difference was huge. At normal ranges i'm sure the 300wm would have wasted tons of its potential with an easy pass through and the extra horsepower not necessary.

I think the magnums have their place but for me that place is if i want to maintain above 1800 fps minimum impact velocity with a certain bulllet at further ranges than what standard cartridges can give me then have to step to the magnums....they make sense for longer range hunting in my eyes. But no intention of killing anything past 500 yrds then standard cartridges plenty, pick good bullet and take down all game on the continent....no magnums required.

[Traps]

Most bullets have maximum penetration at the velocity that just causes deformation - usually 1800-2000 fps. The faster you drive the bullet or in the closer you are the more the bullet deforms. When the bullet deforms and for this excercise I'll assume its a perfect mushroom the frontal area increases exponentially. (area of a circle is 0.25 x pi x radius x radius)
This exponentially large frontal area meets exponentially higher resistance causing much less penetration.

If you take a look at most standard cartridges they can shoot to 500 yards with a speed of 1800-2000 fps where penetration is maximum. This stands against some people's logic - to pick a really fast cartridges expecting better performance. In some cases this may work with violent expansion, but more often than not penetration is the kill king. It begs the question - why drive a bullet faster than needed if it causes less penetration and more often less performance? Also on the other end of the spectrum why choose something that can penetrate three moose end to end? Both alternatives to standard cartridges offer substantially more recoil, powder and incurred cost.