There are a lot of formulas out there for producing numbers which can be used to attempt to compare the effectiveness of different cartridges and loads on game. Some examples are:



kinetic energy

momentum

Taylor knockout value

shock power index (A-square)

penetration index (A-Square)



However, no one has come up with a formula that proves the assertion that penetration increases as velocity decreases. After a bit of mathematical derivation this afternoon, I think I have stumbled onto the formula. Here it is:





Penetration = [1 / velocity] * product price - cost of wheel weights





[Note to the unwitting: This formula is a joke and should not be taken seriously. Nor should anyone who becomes angry reading this relatively feeble joke.]



[Also note: According to the formula, expensive factory loads of cast bullets will penetrate further than your own less expensive reloads. And if the expensive factory leads use cheap materials such as wheel weights or recycled batteries, they will penetrate further than if they use expensive virgin lead or brass.]

All I want to know is if rear entry allows for deeper penetration ? With or with out the wheel weights.

The problem with penetration is that it usually winds up being different every time (on heavy game where the bullet usually doesn't exit).



So even if the formula works one day it will not necessarily work the next. But Penetration Index gives nominally, relatively consistent results from one shot to the next. But even it doesn't account for bullet shape, much less construction.

Then I guess a bowling ball, launched by hand, should penetrate like crazy. Lots of weight at a low velocity!

-Bob F.

Post deleted by 500grains

I once pulled one of those Garrett Hammer Heads off... well while I was looking at the thing, it sliped out of fingers!! Lucky for me... as it was falling I saw that it was headed twards my foot... so I moved my foot. There is no way I am going to pay for a backhoe to dig up my living room to retreve it though, ill just leave it as a conversation piece in the massive hole it left in the floor. I did have two PHs' (Professional Housecontractors) look at the hole though... they said the bullet broke both shoulders of my house!!

No... but it broke both shoulders of a 2nd smaller, more feminine house next door. The PH (professional housecontractor) said he couldnt believe it... I said "... you want to go for 3?" His eyes widened and he naturally got down on his Knees. Later that day he came back over and gave me his high impact plastic hard hat... the type that is in the shape of a Stetson. He said he would have never learned so much or experianced so much in one day as a PH if he hadnt met a man with a pack of Garrets and a 45-70.

Hi 500 gr
When i was young I asked an expert with many years of experience (she was a FRENCH nurse at her 40s and had worked in many countries in Africa) the same question and she told me :THE LONG BIG BULLET AT LOWER VELOCITY HAVE A LOT MORE PENETRATION AND MOMENTUM AND KNOCK DOWN!! POWER THAN LITTLE BULLETS AT HIGH VELOCITY) i respect her advice as an expert!! on balistic and anatomy . se couldn't be wrong!! All is matter of sectional density
regards
and happy easter
danny

I was testing LBT bullets out of the new Marlin African Model 45-70 today, and them holes in the ground are mighty deep! After shooting a mere five rounds I'm half way to China! (Causes earthquakes in third world countries I'm afraid, but thats the price of real penetration.) ~~~Suluuq

Good one!