Ambivalent Skeptic

March 2, 2011

Now a look at efficiency.

Filed under: Ballistics — Clint1911 @ 3:46 pm

A 22 LR cartridge puts a 40 gr bullet at 1200 fps with about 2 gr of powder. Actually it can be somewhere from 1.6 to 2.5 grains, but let us use 2.

IF (and only IF) we could keep that Same efficiency, then a 60 gr bullet at the same speed would use 3 grains of powder. It also means that by using 9 grains of powder we could take that 60 gr bullet and push it at 3600 FPS! (wouldn’t it be nice to have that in .223)

Multiply by three again and we can have a 180 bullet (60 x 3) at 3600 fps for only 27 gr of powder. That would be something to see from a 308. However…

Now, here is the rub. Using hodgdon data at http://data.hodgdon.com, you can see the the 223 max’s out a 40 grain bullet at 3674 fps using 28 gr of powder. The 60 grain-ers max at 3174 with 26 gr of powder.

That’s a far cry from 60 at 3600 with only 9 gr of powder. We can’t even get that speed with that bullet and having one or the other calls for 3 times the powder.

Speaking about 27 grains of powder, let us look at 30 caliber rifles with 180 gr bullets. Comparing, by cartridge, grains of powder vs velocity for the fastest loadings listed.

300 savage:
38.5 grs for 2395 fps

308 win:
45.2 gr of powder for 2683 fps

30-06:
57.5 grs for 2798 fps

300 WSM:
65.0 grs for 2991 fps

300 win mag:
78.5 grs for 3034 fps

300 H and H Mag :
73.0 grs for 3035 fps

300 Wby mag:
77.0 grs for 3171 fps (using Hybrid 100V)
88.5 grs for 3151 fps (using H1000)

300 RUM:
100.5 grs for 3300 fps (using Retumbo at 62,400 PSI  )
96.0 grs for 3218 fps (using H1000)

30-378 Weatherby:
113.0 grs for 3460 fps (using Retumbo)

I included powder types with the last three because Hybrid 100V data was only available for the 300 Wby. As you can see, it upped the speed a little despite a significantly reduced change. It will be interesting to see how this new powder improves the ballistics of the other super mags.
(BTW, the 300 Win Mag with Hybrid 100V uses 67.7 grs for a vel of 2998 fps at 62,400 PSI. That’s over a ten grain reduction for a loss of only 36 fps.)

The next big cartridge is really big.

The Lazzeroni Warbird is “the fastest .30 caliber” according to Rifle Shooter magazine/ http://www.rifleshootermag.com/featured_rifles/RS_fastestman_200910/index1.html

“The Warbird is the fastest .30 caliber available. With Lazzeroni’s loads in a 26-inch barrel you can expect 3,700 fps from a 150-grain bullet and 3,500 fps from a 180-grain bullet. Add two inches of barrel (which Lazz prefers) and you can expect up to 3,825 fps from a 150-grain bullet and just over 3,600 fps from a 180-grain bullet. Zowee.”

I had to look up the Lazzeroni web page for load data.
http://www.lazzeroni.com/ct_reload_Warbird.htm

With a 27 inch barrel the “ABSOLUTE MAXIMUM LOAD IN GRAINS” is 104 of Alliant Reloader 25. This gives a speed of 3560 but that is with a 27 inch barrel at at 66,400 psi.

OK, so we see the Warbird is more efficient than the RUM or Weathery but that is a natural consequence of higher pressure. And it has a longer barrel too.

So which cartridge is the “BEST”?

Well, they all do what they do pretty well. But that’s not a real answer, it’s a given or else the market would have flushed them long ago..

It depends on what kind of “BEST” are you looking for. Do you what maximum velocity? Then the answer is obvious, the Warbird.

But if you want maximum EFFICIENCY then the answer is just as obvious; the 22 long Rifle. Remember we started this ride with a load that pushed 40 grains to 1200 fps with only a speck of propellent.

But the power level leaves something to be desired. Many people, (myself included) find it inhumane to use such a weak projectile on deer. Sure it can work, but that does not means it is a good idea.

So you can see why asking which cartridge is “better” is like asking which is “better” between a tack hammer and a sledge hammer.

So now that I have explained the obvious which is either the first rule of common sense of the hallmark of genius…

Let’s get to the point. Which is: do NOT be impressed by efficiency for the sake of efficiency.

I once read an article where a someone chose a particular design because “it was the best ratio of performance to weight.”

Why should we care?

Spider silk fits the above description but you don’t see it used much in industry do you? That is because while it has high performance for the weight, it is still low performance, barely able to hold up a struggling fly. Also, a flea can jump several times it’s body length. If a human could do that we all could jump over football fields, but if a flea was 6 feet tall is would be crushed by it’s own body weight. Efficient designs at their scale to be sure, but they do not give the performance to be truly useful. Humans out jump fleas as measured in real inches not body lengths. I’m not saying you should be IN-efficient, just that by going after efficiency in and of itself you will eventually have something underpowered.

So when I mention that a something doesn’t look sturdy enough, I don’t take an answer of “its the most efficient design” too seriously. Actually, I do take it seriously, just not in the manner the “experts” hoped. I refuse to trust it and stay away.

Ultimately, who cares if you’re more efficient if you don’t have enough capability? Having the greatest strength-to-weight ratio on Earth is useless if you do not have enough minimum strength to get the job done.

On on that note, we also have an example showing why velocity should not be the end goal of cartridge design. The Warbird is fast but it calls for a 12+ pound rifle. Also, as bullets go faster, the powder efficiency drops. And that matters because recoil matters. In short, getting the same velocity from the same bullet by burning less powder results in less recoil because you have less mass ejecting out the front shoving the gun into your body.

Let’s recap our examples and compare the velocity per grain of powder efficiencies.

vel gr v/gr
30-378 3460 113 30.62
300 rum 3300 100.5 32.84
300 rum 3218 96 33.52
Warbird 3560 104 34.23
300 Wby 3151 88.5 35.6
300 winmag 3034 78.5 38.65
300 Wby 3171 77 41.18
300 HH 3035 73 41.58
300 WSM 2991 65 46.02
30-06 2798 57.5 48.66
308 win 2683 45.2 59.36
300 savage 2395 38.5 62.21
“perfect” 3600 27 133.33

As you can see, the general trend is as the bullet goes faster, the efficiency drops. There are two real exceptions, the Warbird, and the Hybrid 100V loading of the Weatherby. One is due to design and pressure allowances, the other due to optimized powder selection.

And our “perfect” load, a hypothetical 30 cal rifle with the efficiency of a 22 LR, has twice the efficiency of the 300 Savage, thrice for the common hunting calibers, and four times the efficiency of the super mags. Or the 30-378 has HALF the efficiency of the 300 Savage.

This translates into recoil.

Now recoil can be described two ways. First is by Recoil Velocity, which is how fast the gun slams into you. The second is Recoil Energy which is more common. I find recoil velocity a far better indicator of how well one can handle a gun. Think of it as recoil velocity is how much it hurts when you shoot and recoil energy is how much it hurts after you shoot.

More can be read at Chris Byrne’s blog:
http://anarchangel.blogspot.com/2006/12/push-and-kick.html

So credit where credit is due, Chris introduced me (via blog) to recoil velocity as an idea and it has been a big help since.

And while we are at it here is another post about power and optimization that is somewhat related to our current topic.
http://anarchangel.blogspot.com/2008/10/thousand-yard-conspiracy-part-1-paper.html

OK, so back to recoil. Less recoil is better, usually. So let us compare the 30-06, the 300 Win Mag and the 30-378 Weatherby in equal weight guns firing equal weight bullets.

300 Win Mag vs 30-06:
The 300 Win Mag has 8% more speed but 15% more recoil velocity and 27% more recoil energy

30-378 vs 300 Win mag
The 30-378 has 12% more speed but 20% more recoil velocity and 36% more recoil energy

But compare the Warbird to the 30-378:
The Warbird has 2.8% more speed but 1.7% LESS recoil velocity and 3.4% LESS recoil energy

There’s the question of do you really want that extra velocity. Sure if there was no downside we’d take all the speed we can get. But if it is just a-nice-to-have we are better off with a low-cost low-recoil system And if you are going to put up with all the hassle, what are you going to DO with it? Actually that is where the second link to Chris Byrne come’s in. He discusses long range shooting where the magnums really shine. I don’t know about you but I dislike buying capacity that I can never fully appreciate.

I like the idea of owning a 300 Remington Ultra Mag. I would max out the speed only a few times while working up loads for the gun and see how fast she can really go. But afterward? I would back off a few grains of propellent, find a faster-than-winmag velocity that gives the best accuracy and and call it good. From then on, I’d shoot light loads that duplicate 30-06 speeds. Why? Because it is cheaper, less wear on the guns and brass, good enough for paper to 300 yards and it will drop deer just fine. Actually, since we have been discussing 180 gr bullet loads, I should point out the the 150 gr bullets are more than good enough for deer.. The heavier, high speed bullets can be saved for the really big critters like moose and bear. So I can do everything I want to do (and more) with just the one rifle. So I like the idea of having a 300 RUM.

But am I really better off with the 300 RUM over the 30-06?

Let us get the cliche out of the way. Right tool for the right job, etc, etc, etc, …

But what is the right tool? Actually a discussion on “needs” vs “wants” should really be a separate post. So for now I’ll summarize that one should find the performance that they need and opt for a solution that is only slightly more powerful.

Alternately one can find the highest performance level one is comfortable AND proficient with and use that as a general purpose instrument. In fact, that seems to be how most gun buyers today work. Whether you argue the 270 vs 30-06 or not, most hunting done with either can be done with a smaller, less powerful, cartridge with no loss in effectiveness. Using a 7 mm Mauser, 300 Savage, or 25-06 would mean less recoil, or a lighter weapon for the same recoil.

They are just as good within their limits.

And that is a problem. A hidden problem, I believe, as I am seeing an increase in talk about “efficient this” or “optimum that” or “we have the best ratio between these and those”.

For deer a 25-06 is “just as good” as a 30-06. “Good” being defined as how well is drops the animal in its tracts. Some people would say the 25-06 is “better” because it is more controllable, but that is a separate issue. The 25 cal is equally effective on deer and it is more controllable. Certainly a feather in the hat for the little guy, but it does not make it “better” at doing the job. Just a little easier to use.

In other words it can be “better” and it can be “easier” but it should never be “better” because it is “easier”.

And there is still the performance limit. On deer the 30-06 has power to spare. The 25 and 30 cal are functional equal. But what if you up the difficultly? What happens when you go up to elk of moose? Or more range, or more brush in the way?

Is a 25-06 or 308 good for Elk? For moose? For people, who can get close and shoot “good” (however you define that) yes. For others they are going to want a 338 or a 45-70.

But those are two different performance standards.

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