Most "efficient" cartridge for each caliber?

[someguy2800]

I would need some more context of what I want to use it for because if it can't perform the task that I want then it is of no use, and if its overkill for the task then its a waste of powder and recoil. Take for example a 7mm-08. I would consider that to be a pretty efficient 400 yard rifle for deer size game. Its a decent balance of powder used, bullets with decent ballistic coefficients to retain its muzzle energy, and very tolerable recoil. If I change the intended task though it looks less appealing. If I wanted to hunt at very long ranges or hunt very large game I would consider it underpowered and thus not applicable to the task. If I were shooting varmints or handgun silhouette or something like that then I would consider it way overpowered and inefficient because its burning about twice the powder and producing twice the recoil than what is really needed to perform the task. For example a really popular round for handgun silhouettes was a 7mmTCU, which is a 223 case with a 7mm bullet. Its pretty unimpressive on paper, but the name of the game in silhouettes is being able to buck the wind and have enough momentum to knock over the targets, while also having minimum recoil so you don't shoot out your wrist in a long course of fire. So in that application a 7mmTCU is much more efficient than a 7mm08.

 

[Varminterror]

@Double Naught Spy - clearing a squib obviously takes greater force than the propulsion force it stopped. Static friction coefficients being considerably greater than sliding friction coefficients first, but equally, the bullet when fired has its own inertia. I can’t say for certain that a bullet won’t squib if the gas expands to only 1psig, but I know I can’t irrefutably describe the system in which it MUST squib at 1psig. It’s simply not a static system.

 

[Double Naught Spy]

Bullets ain't gliding down a barrel.

 

[Grumpy_old_Fart]

In the automotive world, we compare classes of cars. Sedans against sedans, coupes against coupes, trucks quite the same.

Find a standard.

 

[rayatphonix]

Rather, I'm curious - and feel free to state your opinion - what any of you would consider the optimal cartridge for each caliber.

It’s taken 4 pages to come back to this, and I’ll play. For the 6.5 calibers I would nominate the 6.5 Grendel. 28 grains of powder will get me 2625 fps with 120 gn bullets. The CM will push that same bullet about 300 fps faster, but needs about 44 grains of powder. These are accurate hunting loads with different powders from my rifles. Is is scientific? Nope, but I think the Grendel gives me more performance per grain of powder and it does what I need it to do.

 

[Larry in wyoming]

25 cal = the 250 savage in my mind. 308 in a 30 cal. 223 in a 224 bore. Feel free to disagree.

 

[Nature Boy]

Static friction coefficients being considerably greater than sliding friction coefficients firs

From the dusty recesses of my mind, I seem to recall a college professor referring to that as “Stiction”

 

[Newtosavage]

When I think of which cartridges make the most sense, to me at least, I usually start with bullet weight and bore diameter. Since we're in the business of moving projectiles, ballistic coefficient always comes into play - unless of course your "work" occurs at distances so close that BC simply doesn't matter. But looking at 120-130 class bullets out of a .308 bore, for example. Not the best use of that bore diameter in my opinion. Same thing with 175 class bullets from a 7mm bore. Probably not the best use of that bore even though it's done.

 

[wombat13]

Others have mentioned this, but trying to define one measure of efficiency is a waste of time because it will obscure important differences. It seems to me you have to set particular parameters then you can identify the most efficient with those constraints. For example, first are we hunting or target shooting? Punching holes in paper requires no meaningful energy delivered on target, so one would reduce bullet weight relative to hunting applications. Again, with target shooting often one is shooting known distance or can use a range finder. That would mean that judging wind is probably where the most error and difficulty will be. So, one would probably prioritize low recoil and high BC to reduce wind deflection. When it comes to hunting you have to factor in "how much killing" the quarry will require and at what distance. "How much killing" is complicated: How big a hole? How much mass? What minimum sectional density? What minimum velocity and/or energy?

I've played around with this a bit because I enjoy analysis for the sake of analysis. So here is one approach I took: Elk appropriate loads (SD >0.249). Max ethical range defined as maximum distance where the bullet will have at least 1,000 ft-lbs and 2,200 fps. Now we can do a couple of things. Plot standard loads (taken from Hodgdon online data and plugged into Hornady online ballistics) with Recoil energy on one axis and Max ethical range on the other. I then used the the .308 win load with the highest max ethical range (168 gr bullet) as a reference and compared other chamberings/loads to it.



So in this analysis, there are four loads/chamberings that can launch a bullet with SD >0.249 with both greater max ethical range and with less recoil than the best .308 win load. Those four are 6.5 creed (130 gr bullet) and 6.5-06 (130 gr and 140 gr bullets) and .270 win (140 gr bullet).

I have a number of other charts that look at different parameters if anyone is interested.

 

[Newtosavage]

Others have mentioned this, but trying to define one measure of efficiency is a waste of time because it will obscure important differences. It seems to me you have to set particular parameters then you can identify the most efficient with those constraints. For example, first are we hunting or target shooting? Punching holes in paper requires no meaningful energy delivered on target, so one would reduce bullet weight relative to hunting applications. Again, with target shooting often one is shooting known distance or can use a range finder. That would mean that judging wind is probably where the most error and difficulty will be. So, one would probably prioritize low recoil and high BC to reduce wind deflection. When it comes to hunting you have to factor in "how much killing" the quarry will require and at what distance. "How much killing" is complicated: How big a hole? How much mass? What minimum sectional density? What minimum velocity and/or energy?

I've played around with this a bit because I enjoy analysis for the sake of analysis. So here is one approach I took: Elk appropriate loads (SD >0.249). Max ethical range defined as maximum distance where the bullet will have at least 1,000 ft-lbs and 2,200 fps. Now we can do a couple of things. Plot standard loads (taken from Hodgdon online data and plugged into Hornady online ballistics) with Recoil energy on one axis and Max ethical range on the other. I then used the the .308 win load with the highest max ethical range (168 gr bullet) as a reference and compared other chamberings/loads to it.

View attachment 1056924

So in this analysis, there are four loads/chamberings that can launch a bullet with SD >0.249 with both greater max ethical range and with less recoil than the best .308 win load. Those four are 6.5 creed (130 gr bullet) and 6.5-06 (130 gr and 140 gr bullets) and .270 win (140 gr bullet).

I have a number of other charts that look at different parameters if anyone is interested.

So this is kinda what I meant by "efficient." Maybe "logical" is a better word, but your analysis is what I had in mind. Kinda surprised someone hasn't put this in an app or online calculator already to be honest.

As much as gun guys and gals enjoy comparing and discussing and arguing over different cartridges, I would have thought someone would put some data behind those arguments. I've seen plenty of folks who have done their own analysis, similar to yours, but nothing more universally accessible for the masses.

 

[Larry in wyoming]

Well, part of the problem with this whole idea is that you have cartridges that kill out of all proportion to their size. The 250 savage is a great example. Whether it is low recoil and low muzzle blast making shot placement easier or just good bullets or (not likely) just PFM (Pure Freaking Magic).

It's really a good thing that there are no solid answers. If there were, we'd only have women to talk about around the campfire. And if you think this is a topic that is confusing and without solid answers.....

 

[Newtosavage]

I'm a visual person, and I really like Wombat's graph. It gets to the question I had in my mind very well.

 

[wombat13]

Here's the same chart but with a line added. The blue line represents proportional increase/decrease of recoil and max ethical range. A round with 10% greater recoil and 10% greater max ethical range (compared to the best .308 win load) would lie exactly on the blue line. More "efficient" cartridges/loads lie below the blue line (i.e., range increases more than recoil or recoil decreases more than range).



Now we can see the popularity of the 7mm and 6.5mm cartridges. They are consistently more "efficient" (in the sense of max ethical range relative to recoil) than .308 win. The light green dots at the bottom with ranges of 300 and 400 are 6.5 creed. The purple dots above and right of 6.5 creed are 6.5-06. The green dots below the reference .308 win are 7mm-08. Up and to the right are two orange dots for .280rem. Well to the right but still below the blue line are blue dots for .280ai and brown dots for 7mmRM. The light blue dots directly to the right of the reference .308 win are .270 win. The red dot just above the blue line on the far right is .300WM.

This is the analysis that got me fired up about .280ai. It lets you send elk appropriate bullets (150+ grs, 0.266+ sd) out to magnum ranges (matching 7mmRM and most .300WM loads in range) with the minimum increase in recoil.

 

[someguy2800]

Here's the same chart but with a line added. The blue line represents proportional increase/decrease of recoil and max ethical range. A round with 10% greater recoil and 10% greater max ethical range (compared to the best .308 win load) would lie exactly on the blue line. More "efficient" cartridges/loads lie below the blue line (i.e., range increases more than recoil or recoil decreases more than range).

View attachment 1056949

Now we can see the popularity of the 7mm and 6.5mm cartridges. They are consistently more "efficient" (in the sense of max ethical range relative to recoil) than .308 win. The light green dots at the bottom with ranges of 300 and 400 are 6.5 creed. The purple dots above and right of 6.5 creed are 6.5-06. The green dots below the reference .308 win are 7mm-08. Up and to the right are two orange dots for .280rem. Well to the right but still below the blue line are blue dots for .280ai and brown dots for 7mmRM. The light blue dots directly to the right of the reference .308 win are .270 win. The red dot just above the blue line on the far right is .300WM.

This is the analysis that got me fired up about .280ai. It lets you send elk appropriate bullets (150+ grs, 0.266+ sd) out to magnum ranges (matching 7mmRM and most .300WM loads in range) with the minimum increase in recoil.

great analysis!

 

[wombat13]

Another parameter to consider is the bore size or "how big a hole do I need to make?" It's difficult to graphically represent more than 2 dimensions, so if we add bore size we have to eliminate something or condense. Here's an attempt to incorporate hole size.



Given that we are restricting this to bullets with SD > .249, increasing hole size means increasing mass. Increasing mass either reduces range or increases recoil (or does both if the round is inefficient). So the blue line represents an "efficiency frontier" based on the commonly accepted rounds in given bore diameters. For example, the commonly purchased .375 is the .375 H&H; .338 is the .338WM, and .308 is the .308 win. So if I start with the .375 H&H that has the best ratio of max ethical range to recoil energy, when I reduce hole size I should be getting an increase in range/recoil. But how much? Well, let's draw a straight line to .338WM (our second standard). We should continue to gain improve range/recoil as we reduce hole size, so draw a line through .308 win (our third standard). Now anything that is to the right of the blue line is more efficient range/recoil relative to the hole size.

I take away three things from the above chart. First, there is a good reason that .308 win and .338WM are considered the standard in the calibers. The second is that we see the usual suspects looking good. 6.5 creed and 6.5-06 are to the right of the line. .25-06 is also to the right of the line, but this is marginal (the SD is exactly 0.249 and many would consider .257 too small for elk). Also note that .280ai is touching the line, so that's pretty darn good. Finally, we can see that .375 Ruger represents an actual improvement over .375 H&H.

 

[wombat13]

The charts I posted above all prioritize max ethical range. But what if we aren't worried about range? What if we really just want to really want "maximum killing" for our recoil. First, let's assume we are using premium bullets that will hold together at high velocity. If that's true, we want as much mass and velocity as we can get. Now, we also know that sectional density is important for penetration. Given that, I created a chart using "Momentum Density" which is sectional density times muzzle velocity. Higher momentum density is related to muzzle energy (since both depend on mass and velocity) and sectional density our best measure for good penetration.



Now what do we see? .375H&H and .308 win both still look really good. 6.5 creed also looks pretty good as it is close to the efficiency line. Now we see why people like .35 Whelen and .338-06. Big bore and a lot of mass will really put the smack down on a critter. They don't have the velocity to keep up with the .338WM in terms of range and wind drift, but if we're shooting inside of 200 yards, so what?

 

[someguy2800]

It took me awhile to understand what you are doing here but I get it now. If I may offer a suggestion, the charts would be easier to read if the legend wasn't in the reverse order of how the data is displayed on the chart. Also how are you defining the hole size? I don't understand that.

 

[wombat13]

It took me awhile to understand what you are doing here but I get it now. If I may offer a suggestion, the charts would be easier to read if the legend wasn't in the reverse order of how the data is displayed on the chart. Also how are you defining the hole size? I don't understand that.

Hole size is the area of the bore (Pi*r^2). Yes, the legend is backward, but that's the default. I'd have to rearrange them manually. I can do that if anyone really wants to use these.

 

[someguy2800]

Ah, I see

 

[wombat13]

Okay, here are the charts with the legends ordered from largest bore diameter at the top to smallest at the bottom:

 

[Varminterror]

I'm a visual person, and I really like Wombat's graph. It gets to the question I had in my mind very well.

Not a criticism of the work done, but I’ll point to the facts the analysis done is based only upon comparative reference, and the x axis in that graph is “max ethical range,” which is an imaginary, subjective construct based on THAT programmer’s individual belief. A max ethical range of 350 yards with a 308win? But the max ethical range of a 6.5 creed is 400 yards. What objective standard would support that differentiation? It’s just a subjective programmer input which is now disguised as an objective mathematical parameter because they displayed it on a scatter plot…

 

[someguy2800]

Not a criticism of the work done, but I’ll point to the facts the analysis done is based only upon comparative reference, and the x axis in that graph is “max ethical range,” which is an imaginary, subjective construct based on THAT programmer’s individual belief. A max ethical range of 350 yards with a 308win? But the max ethical range of a 6.5 creed is 400 yards. What objective standard would support that differentiation? It’s just a subjective programmer input which is now disguised as an objective mathematical parameter because they displayed it on a scatter plot…

It is based on his opinion and he did not represent it otherwise. Your adding nothing to this conversation.

 

[wombat13]

Not a criticism of the work done, but I’ll point to the facts the analysis done is based only upon comparative reference, and the x axis in that graph is “max ethical range,” which is an imaginary, subjective construct based on THAT programmer’s individual belief. A max ethical range of 350 yards with a 308win? But the max ethical range of a 6.5 creed is 400 yards. What objective standard would support that differentiation? It’s just a subjective programmer input which is now disguised as an objective mathematical parameter because they displayed it on a scatter plot…

You can say subjective as much as you like, but it isn't. I wrote what the criteria were. (By the way, subjective means that the difference exists only in the mind of the observer). This analysis is correct in pointing out differences. You can disagree with the criteria being the correct ones to use, but that doesn't make it subjective. I defined "max ethical range" as the maximum range at which the bullet would have both 2,200 ft/s velocity and 1,000 ft-lbs of energy. Did I personally load each of these and do extensive testing to confirm these numbers? No. This is based on published data. Your actual results may vary, etc. etc.

Is this the be all end all? No. I specifically wrote that this is too complicated to calculate the "best" cartridge. You have to look at things in different ways, looking at the ways different parameters affect what you think is important.

You obviously know quite a bit, but you like to crap all over everyone else and it gets tiresome.

 

[wombat13]

It is based on his opinion and he did not represent it otherwise. Your adding nothing to this conversation.

Thank you. The only way this is based on opinion is that I used my opinion (or judgment) on what the important criteria are. There is nothing wrong the the analysis given the criteria. People may disagree on the critieria to use. Fine. I'd even be happy to look at different criteria if anyone has suggestions.

 

[Varminterror]

You can say subjective as much as you like, but it isn't.

“Ethics” aren’t objective. So your underlying parameter of maximum ethical range is absolutely subjective.

Presenting opinions on scatter plots doesn’t well represent the subjective nature of the opinion.

This has been my contention throughout - I’d love to pretend some objective analysis could be done in this space, but it always ends in an empty set… when we try to force relevance, we end with an over defined set of parameters and more and more subjective influence into the game…

As I said before, it’s no criticism of the work you’ve done, but it’s simply the nature of the work being done - in the end, when these things are built, they come back to some subjective preference and some overdefined parameter set (for example, downrange energy and trajectory are both dependent upon the same variable of MV, so ratios among those end up double counting single variables).

I’ve seen this discussion happen on forums several times since at least 1998 that I recall - it always ends the same. exact. way… overdefined and subjective, which isn’t objective mathematical comparison.