Bullet Penetration

[tnek13]

E=M(VxV) I do not know how to type squared in the formula. Anyway, the Kinetic energy available at impact is dependant on the weight of bullet and speed of impact. Velocity at the muzzle is less important that velocity at impact, that is where BC becomes a factor, as well as bullet design. Match your bullet to the intended game, expected range, etc. Manufacturers will tell you the expansion expectation at expected velocity.

 

[Aussie Hunter Steve]

Bullets or different calibre with similar SD's will penetrate similar so long as their design is the same. Penetration depends primarily on bullet design and construction, eg, most Nosler BT's and AB's have identical SD and BC, but the more stoutly constructed AB's will penetrate much further in an animal.
Regarding different diameters, if the cartridge is adequate it will work. But as the game gets larger, all other things being equal, larger diameter bullets do leave a bigger wound channel and kill more efficiently. The bigger bullet is also more effective when encountering heavy bones as the extra weight possesses greater smashing ability.

 

[azsugarbear]

The size of the wound channel is only a small part of the story. There is ample evidence out there in the hunting world of small, fast bullets killing large game. I am not advocating this, but rather bringing it up to point out the importance of hydraulic shock. The sound/shock wave that follows the bullet into the wound cavity can be far more disruptive to tissue than the actual expanded bullet itself. This is readily seen on youtube videos where bullets (both pistol and rifle) are shot into gelatin medium. The damage to actual tissue is often greater then what is seen with the gelatin itself. I have gutted several animals and found lungs, spleens, kidneys, etc. that appeared torn or ripped open that were not part of the wound channel itself. Obviously, this hydraulic shock is only of value when bullets are directed at the "boiler room"

 

[aushunter1]

With all the 6.5mm bullet hype, assuming the bullet is the same design, traveling the same speed, with similar SD, can we assume penetration will be similar With different calibers

140 6.5 accubond vs 180gr .308

130gr tsx in 6.5 vs 165gr .3089

Other than a larger wound channel, can the 6.5 get the job done.

I see guys using 6.5prc to 1000 yards, it's 300 fps faster than the cm. At the same impact velocities the 6.5cm can still really reach out there.

For bears and big animals, if the smaller bullet penetrates as deeply, is the larger wound channel going to kill faster assuming similiar shot placement.

How about a 6.5 140 gr accubond at 2750 fps vs .338 200gr accubond at 2650 fps

I am really interested to hear if a 6.5cm with a Barnes tsx or a 130 lrx can penetrate with the bigger guns or go deeper.

130gr 6.5 tsx vs .308 180gr parition or accubond at the same speed as each other?

Thanks for opinions, assuming same speed please rank the bullets as far as penetration goes.

Thanks again

Your asking 2 questions here, for the question in red heavier projectiles traveling close to the same speed the heavier one will have more energy, its like a 1 tonne car & a 2 tonne car traveling at the same speed side by side & trying to stop, the heavier car will take longer to stop due to its weight.

With the question in blue, it is subject to bullet design but again the heavier projectile has more mass behind it so should have deeper penetration.
Imo you better of not doing such comparisons & just look at them individually, one way to do that is find ballistic gel tests like these.

 

[nocannons]

Another thing to remember is how the heavier bullet will retain momentum after impact. On that note one could say the smaller diameter bullet will have less drag. You did say though travelling the same speed. I would give the nod to the larger caliber bullet doing a better job. I do like the 6.5's but believe they have their limits.

AS one who does not tolerate recoil well the 243 has been my choice for many years. I do not understand why people think you have to use larger calibers to be able to shoot whitetail deer. Used 87 gr. vld hunting bullets for about ten years. No problems other than occasionally hitting shoulder on far side. Have new rifle (REM 783) that I am trying 95 gr. hybrids that look like they will be good shooters. Will see how well they work on deer come November.

 

[Wedgy]

Bullets or different calibre with similar SD's will penetrate similar so long as their design is the same. Penetration depends primarily on bullet design and construction, eg, most Nosler BT's and AB's have identical SD and BC, but the more stoutly constructed AB's will penetrate much further in an animal.

You have not encountered the solid alloy of Barnes bullets yet, it is not in any way similar to a lead bullet. Monos are nothing like lead bullets, especially the Barnes, they are more like steel compared to other non lead offerings. Literally 100% weight retention

 

[Aussie Hunter Steve]

You have not encountered the solid alloy of Barnes bullets yet, it is not in any way similar to a lead bullet. Monos are nothing like lead bullets, especially the Barnes, they are more like steel compared to other non lead offerings. Literally 100% weight retention

I've used a lot of Barnes bullets in various cartridges on everything from bunnies to buffalo. In making my point I did say about other factors being equal. Sorry if you didn't understand that properly.

 

[RockyMtnMT]

There is so much variable in the op question that it almost can't be answered well. Different bullets construction and results on impact make for to many variables.

So I think the Right answer is, larger caliber bullets Hit harder than smaller ones. I don't think you can be over gunned, but you sure can be under gunned.

 

[Jerry D]

Thanks for feedback everyone.

The reason I asked is two fold. I am looking for a short action cartridge for a custom hunting gun with a 20" barrel.

My ideal cartridge is a 7mm08 for its balance of velocity, sd, bc, diameter and low recoil. Wish it was more popular!

I live in an area where you cant hunt coyotes with anything .270 or larger, so even a .270 win is actually larger and not allowed

That then leads me down to the 6.5cm. Barrel life isnt as good, little smaller frontal area but higher bc and sd, nice recoil, little slower off the hop, but popular!

Due to the restriction, I feel a 6.5 is my best option or have 2 guns but that isnt in the cards right now.

The .308 is a great round, just prefer something with a tad less recoil but will reconsider it due to barrel life, popularity, and larger bore and effecincy in a 20" barrel. .308 with 150s or 165s max I would think.

Thanks everyone.

Rifle specs
Apollo lite action
20" rem mag sporter contour
Ag privateer stock
Hawkins bdl
Triggertech special

 

[manitou]

The size of the wound channel is only a small part of the story. There is ample evidence out there in the hunting world of small, fast bullets killing large game. I am not advocating this, but rather bringing it up to point out the importance of hydraulic shock. The sound/shock wave that follows the bullet into the wound cavity can be far more disruptive to tissue than the actual expanded bullet itself. This is readily seen on youtube videos where bullets (both pistol and rifle) are shot into gelatin medium. The damage to actual tissue is often greater then what is seen with the gelatin itself. I have gutted several animals and found lungs, spleens, kidneys, etc. that appeared torn or ripped open that were not part of the wound channel itself. Obviously, this hydraulic shock is only of value when bullets are directed at the "boiler room"

Actually, hydrostatic shock is caused by the energy of the bullet "pushing" or "forcing" tissue out of the way. It is the transference of this energy upon a mostly liquid material. Liquid does not compress, thus the reason hyrostatic tansmissions and hydraulic cylindars are so effective at transferring energy. So, the bullet entering a mostly liquid matter creates waves of energy that "shove" this matter out of the way in multiple directions... and since this matter is primarily liquid, it in turn continues the energy wave of shoving additional matter away, causing this shock wave. Kind of like throwing a pebble into a pond. You see circular rings emanating away from the point where the pebble entered the water. Liquid pushing liquid out of the way, each ring or series of rings absorbing energy until the energy dissipates, along with the shock wave.

 

[Ingwe]

There is so much variable in the op question that it almost can't be answered well. Different bullets construction and results on impact make for to many variables.

So I think the Right answer is, larger caliber bullets Hit harder than smaller ones. I don't think you can be over gunned, but you sure can be under gunned.

+1

 

[shootski]

All of you have some great practices and ideas on what works to be respectful of the prey...up to a point. Let me explain my thought.
These days I only hunt with airguns, mostly what is called Big Bore by airgun hunters (bigger than .25 caliber) .308, .458, and .58 caliber. I'm shooting dead soft lead ball/bullet up to 510 grain all subsonic (under 1,000 FPS) to effective (Long Range Airgun Hunting) ranges of 150+ meters. So what?
Hunting is about giving consideration of worst case for the prey! That is of course an animal that runs and you need to follow. That takes a blood trail aided by some great tracking skills! Therefore a larger round with a larger meplat does a more consistent job of providing a blood trail!

Train for the best and plan for the worst.
Show your respect for the prey; chose accordingly!

Stay well! Wash those hands!

shootski