Footpounds of Energy Limit

[MOA Chaser]

I've always limited my rifle/ammo and effective hunting range based on a minimum of 1,000 foot pounds of energy at that specific range. I remember reading that years ago in several rifle and hunting books and periodicals. I was checking zero on my 257 Bee yesterday (sweet gun, <1 MOA) using 100 Grain BT's and based on my ballistic tables the energy beyond 500 yards drops below 1,000 foot pounds at a velocity of 1311 fps. So, my opinion is that this particular rifle/bullet combination has an effective deer hunting range of 500 yards. I have shot a few deer at that distance (only when I felt very comfortable with the shot) and all have been DRT with the rifle/bullet performing flawlessly (through and through shots, no bullet recovered). So, is there anyone out there as anal as I or is this reasoning even worth considering as some form of baseline in regard to accurate and ethical shooting distance?

 

[CliffM]

I am one if those that do not consider ft/lbs of energy in limiting my range to kill an animal at certain distance. I do however consider that it takes a certain amount of energy to deform any bullet, some take more than others, some less. The bullet choice is more important to me than a certain number created by a mathematical formula. That has alot to do why I prefer heavy for caliber bullets. I shoot a lot of bullets into test media out to 1k, which really only good for comparing one bullet to another. So far nothing that I have used totally predicts what will happen when a bullet gets into an animal. One example is one year we shot 3 antelope using 22, 6.5, and 338. cal Berger bullets. When the hides were off you could tell which caliber killed which animal, but the difference in damage was not as much a one would expect considering the difference in the amount of energy involved.
Cliff

 

[MOA Chaser]

Thanks Cliff. Were those antelope all taken at the same distance? Using my "rule of thumb", and for the sake of argument...let's say a 30-30 loaded with a 150 grain bullet has a retained energy of about 800 footpounds at 200 yards. Most of us will agree that a 30-30 is basically a 200 yard weapon. I just find it simple to use footpounds as a minimum standard in how far I should shoot at a game animal. I routinely shoot steel and paper out to 900 yards (I can't find a 1,000 yard place to shoot!!) but there are only a few rifles I own that have the retained energy at that distance to meet my minimum energy level. Most are the big heavier bullet calibers like you mentioned.

 

[Greyfox]

I think that the 1000 Ft/Pd at target is only a guideline. The factor's that I pay strict attention to is bullet performance and shot placement. Using"energy only" as a factor can get you in trouble if the bullet just pencils through the animal, particularly if the central plumbing or spinal column is not damaged.

 

[MOA Chaser]

I think that the 1000 Ft/Pd at target is only a guideline. The factor's that I pay strict attention to is bullet performance and shot placement. Using"energy only" as a factor can get you in trouble if the bullet just pencils through the animal, particularly if the central plumbing or spinal column is not damaged.

Or the exact opposite. Take for example the .300 Blackout that some think is the ultimate hunting round. I recently read an article where the author extolled the virtue of the 110 grain Barnes TAC-TX bullet having wonderful penetration and expansion out to 300 yards. This from a bullet that has only 1100 ft/pds of energy at the muzzle. What did he shoot at 300 yards? I can't imagine that little 110 grain bullet penetrating the hide of a big boar hog, expand, bust a bone or two, and consistently kill at 300 yards. But someone will be sure to try it.

I agree that bullet performance and shot placement are all critical, but even those are based on velocity and energy. Reduce velocity and it will affect energy which will effect bullet performance and possibly shot placement. I've been trying to figure out a simple solution for my hunting style and equipment that will give me a degree of confidence in terminal ballistics. Given the right bullet, the perfect shot placement and knowing that I have enough "power" behind the bullet to get the job done is what I'm looking for. I picked 1,000 foot pounds of energy as my limiting range factor. It's probably a little bit conservative but I can accept it. My 300 with 180 gr Partitions has 1,000 ft/pds at nearly 1,000 yards. Given the opportunity, with all the right conditions, I say it is good to 1K for hunting. A lot on here will most likely agree. I hope...

 

[Greyfox]

Or the exact opposite. Take for example the .300 Blackout that some think is the ultimate hunting round. I recently read an article where the author extolled the virtue of the 110 grain Barnes TAC-TX bullet having wonderful penetration and expansion out to 300 yards. This from a bullet that has only 1100 ft/pds of energy at the muzzle. What did he shoot at 300 yards? I can't imagine that little 110 grain bullet penetrating the hide of a big boar hog, expand, bust a bone or two, and consistently kill at 300 yards. But someone will be sure to try it.

I agree that bullet performance and shot placement are all critical, but even those are based on velocity and energy. Reduce velocity and it will affect energy which will effect bullet performance and possibly shot placement. I've been trying to figure out a simple solution for my hunting style and equipment that will give me a degree of confidence in terminal ballistics. Given the right bullet, the perfect shot placement and knowing that I have enough "power" behind the bullet to get the job done is what I'm looking for. I picked 1,000 foot pounds of energy as my limiting range factor. It's probably a little bit conservative but I can accept it. My 300 with 180 gr Partitions has 1,000 ft/pds at nearly 1,000 yards. Given the opportunity, with all the right conditions, I say it is good to 1K for hunting. A lot on here will most likely agree. I hope...

A formula that I like better than just ft/lbs is the John Taylor formula for "knock out factor". While it was originally intended for solid bullet terminal performance, I think it is more relevant than using foot pounds alone. The way I use it is to first make sure I have a bullet that gives sufficient expansion at the terminal velocity, then take the factor and apply it to the size of the game being hunted. Even if the bullet doesn't expand, it will generally give sufficient penetration. This method places more emphasis on bullet diameter and weight. For medium sized game like deer/antelope I like a factor around 10. For elk sized game, I like a factor around 15. The formula is as follows:

(bullet diameter x bullet weight x velocity at target) divided by 7000

My 300WM:
(.308 diameter) x (210gr) x (1800FPS at 1000 yards) =(116,424) / 7000 =16.6

Try the formula with some of your pet loads!!

 

[MOA Chaser]

Thank you. That looks like good stuff!

 

[CliffM]

Thanks Cliff. Were those antelope all taken at the same distance? Using my "rule of thumb", and for the sake of argument...let's say a 30-30 loaded with a 150 grain bullet has a retained energy of about 800 footpounds at 200 yards. Most of us will agree that a 30-30 is basically a 200 yard weapon. I just find it simple to use footpounds as a minimum standard in how far I should shoot at a game animal. I routinely shoot steel and paper out to 900 yards (I can't find a 1,000 yard place to shoot!!) but there are only a few rifles I own that have the retained energy at that distance to meet my minimum energy level. Most are the big heavier bullet calibers like you mentioned.

The 22- 500+, 6.5- 600+, 338- inside 300yds IIRC.
Cliff

 

[MMERSS]

An effective range is any range at which a shooter/weapon/ammunition combination will achieve a desired effect. Maximum effective range is the maximum range at which a shooter/weapon/ammunition combination will achieve this effect.

One desired effect with big game hunting is a quick and clean kill. Both accuracy and sufficient terminal performance are necessary to achieve this. As such, range is a control measure with this endeavor.

So what is effective range hunting and is this different than shooting at an effective range?

One description of effective range hunting: Thinking outside while shooting inside the box -the marriage between an optimist and vigilant pessimist…….two vastly different yet complementing personalities of vision.

What could this description mean? When dealing in a realm of inaccuracies and uncertainties are there polar ends to vision, that being an optimistic and a vigilant pessimistic vision to effective range hunting? Or simplified, not leaving a quick and clean kill to chance.

 

[Rogmay]

Greyfox, i understand that the equation is just a reference, not sure if I agree with it! with those calculations my 7mm shooting my 180 hybrid at 2900fps MV means I would be short on power past 700yrds with a power factor of 15! Are you running a hot load to get that 210gr bullet going 3100 MV?

 

[srhaggerty]

Geryfox,

Is that factor species dependant for you? I hunt elk with a bow and know how tough they are. I have only shot deer and antelope with rifle and feel they are less tough than elk. I ask because I have been considering barreling to a 284 win for deer sized game. I figured I would be good out to 800 if I did my part.

 

[Greyfox]

Greyfox, i understand that the equation is just a reference, not sure if I agree with it! with those calculations my 7mm shooting my 180 hybrid at 2900fps MV means I would be short on power past 700yrds with a power factor of 15! Are you running a hot load to get that 210gr bullet going 3100 MV?

I get that factor using 2900FPS at an elevation of 5000ft. Not a very hot load, 79 gr of Retumbo. What is your velocity at 700/800 yards?

 

[FEENIX]

An effective range is any range at which a shooter/weapon/ammunition combination will achieve a desired effect. Maximum effective range is the maximum range at which a shooter/weapon/ammunition combination will achieve this effect.

One desired effect with big game hunting is a quick and clean kill. Both accuracy and sufficient terminal performance are necessary to achieve this. As such, range is a control measure with this endeavor.

So what is effective range hunting and is this different than shooting at an effective range?

One description of effective range hunting: Thinking outside while shooting inside the box -the marriage between an optimist and vigilant pessimist…….two vastly different yet complementing personalities of vision.

What could this description mean? When dealing in a realm of inaccuracies and uncertainties are there polar ends to vision, that being an optimistic and a vigilant pessimistic vision to effective range hunting? Or simplified, not leaving a quick and clean kill to chance.

Very well said Sir! I too adhere to a similar principle. It's an unwritten rule but I try (???) to keep the energy at POI regardless of caliber/chambering at 1000 FT-LBS and 1500 FT-LBS for deer and elk size game respectively. Having said that, I harvested a MT elk in 2013 at 931 yards using 190 Berger VLD out of my .300 WM with a calculated energy at POI of ~1300 FT-LBS.

 

[MMERSS]

Very well said Sir! I too adhere to a similar principle. It's an unwritten rule but I try (???) to keep the energy at POI regardless of caliber/chambering at 1000 FT-LBS and 1500 FT-LBS for deer and elk size game respectively. Having said that, I harvested a MT elk in 2013 at 931 yards using 190 Berger VLD out of my .300 WM with a calculated energy at POI of ~1300 FT-LBS.

Outside of energy, what about accuracy? Did you have first round accuracy to achieve the 1300 ftlbs of killing power at 931 yards? If so, were you near the limit of maximum effective range or could the situation allowed for greater range? If not first round accuracy, at what range would you consider a maximum effective range based off the current conditions and shooter/weapon/ammo confidence limits?