[Stinky Coyote]

Originally Posted by Subaru297

In a theoretical world Stinky is correct in his statement that penetration will be equal.
Penetration is reliant on two factors. Sectional density and velocity.

So if velocity is equal and SD are equal the 200gr .30 caliber bullet and the 6.5mm 147gr bullet will both penetrate the same amount. Let's call it 30 inches for now. This is also assuming neither bullet deforms and the SD remains identical in both cases.
We all know the energy of the .30 cal bullet is higher and it uses this energy to create a larger wound channel but penetration is still equal. Energy equals work, or damage in this case.

But we don't live in a theoretical world where bullets don't deform, in fact we want them to deform.

SD is still important for terminal ballistics but it changes as soon as the bullet deforms and sheds weight.

Let's assume 80% weight retention and double diameter expansion.

147gr 6.5mm (0.2644 diameter)

147/(7000*0.2644^2)=0.300 original SD
117.6/(7000*0.529^2)=0.060 terminal SD

200gr 0.30 cal (0.308 diameter)

200/(7000*0.308^2)=0.301 original SD
160/(7000*0.616^2)=0.060 terminal SD

Well I must admit I wasn't expecting the same terminal SD

So penetration will still be equal if both bullets deform and shed the same proportion of weight. So penetration is really dependent on bullet construction! Which we all knew already, right?

So yes, Stinky is right, penetration will be the same but the larger bullet will impact with more energy creating a larger wound channel.

Now whether a 0.529 inch hole through both lungs is significantly different than a 0.616 inch hole.....I don't know that equation, sorry.

Shot placement is always key. So if you can shoot your 6.5 whatever more accurately than your 0.30 whatever then the 6.5 will perform better. If you can shoot whatever your using accurately you are good to go.

Now where was that recoil thread?

Thankyou for a great polite thought out response.

And this is where it’s up to the individual to weigh out whether that 50-60% more recoil energy translates into 50-60% more wound channel energy, or 50-60% faster kill, or however you’d like to quantify it????

I’m not telling people what the answer is there, I know personally that the ratio isn’t equal so I choose far less recoil energy and apply better understanding of impact velocity, sd and construction and shoot better too. Which goes hand in hand with reduced recoil energy.

I would only be able to guess that the ratio of extra recoil energy to the added benefit of on target energy would be maybe less than 1/4 or a 5th gain for more than double the recoil. No thanks. Who has math that can quantify that?

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