In Search of a Fair Comparison

M.L. McPherson

caliber comparisons and fairness

Many are not able to remain objective thru the process Doc, this web site illustrates that perfectly.

Don't know how familiar you are with McPherson's writings, he is a regular contributor to The Varmint Hunter Magazine and has written quite a number of quality articles on the aspects of ballistics, especially interior ballistics. Interesting character and an accomplished long range shooter.

I had heard of him but that was the first of his articles that I read.

I thought he had a good head on his shoulders from the article.

There is a great deal of BS published in the gun magazines - remember they're in the business to sell magazines and advertisements. Who buys the advertisements? - the gun/ammo manufacturers, who want favorable articles!

If anyone would like to REALLY understand internal and external ballistics and compare the various cartridges fairly - that is, when loaded with roughly equivalent bullets to the same PSIs with the same powders and barrel lengths - BUY the computer program QUICK LOAD and QUICK TARGET from NECO. It's worth every penny. You can play with this program, put in your parameters and get the results. As you do this, you'll be learning the TRUTH about cartridge performance.

You will reach a few inexorable conclusions:

1. The bigger the case capacity, the more powder, and the more velocity - everything else being equal (ie., same powder, same bullet wt., and barrel length, etc.). As you pack in more powder, you're packing in more energy to be transferred to the bullet.

2. As case capacity goes up and bore-size goes down, the cartridge becomes less efficient causing more muzzle blast and kick - that is, increasing overbore characteristics and often with shorter barrel life.

3. More barrel length means more velocity but with diminishing returns.

4. Bullets with higher ballistic coefficients (BCs) retain their velocity and energy better than those with lesser BCs.

5. The best performing powders are the SLOWEST BURNING powders you can use with that specific case/bullet combination that will bring the PSI to the desired level (ie., for me, 65,000 for high-powered rifles).

QL will allow you to KNOW rather than rely on biased articles.

AIU, not sure I'd disagree with any of your numbered comments in the main, but am equally sure I'm not tracking your first part of the post. I don't find The Varmint Hunter Magazine filled with the usual hype, nor does Mic McPherson dispense such drivel. VHM is published by the VHA, a private association headquartered somewhere in the Dakotas. It's content comes from members, not staff hacks.

FWIW I don't consider the ability to manipulate computer software equivalent to understanding anything, certainly not ballistics. No slam intended by that. For the most part it isn't necessary to understand any of the associated science to be a successful hunter, or short range shooter, but it is useful for long range and/or precision work.

DD, "gun magazines" are a large - very large - group of periodicals. Although I've read much of it in the past, I don't read much of it anymore, since it's so repetitive and I rarely learn much new. Also, QL/QT is based on sound internal and external ballistic science. If you understand it, you know much. Do you have the program?

No I don't. I have been perusing the world of ballistics to a degree and am still grappling with some aspects of external ballistics. Internal will be the next adventure in depth. I think(dangerous) that I have some knowledge of some of the basics there, ER/burn rate/quickness/pressure curves etc., but mostly know that I don't know much about that particular facet. The primary reason I do not have the programs is that they generate probabilities, not certainty. Some day perhaps. What I do know for a fact is that one will never understand why things really happen in regards to external ballistics by using an EB calculator. It is an assumption I project on internal ballistics theory as well. I'm not sure that terminal ballistics has progressed beyond Vodoo-101 at this juncture, and it may have to wait for the next life. Too much chaos in that world.

I understand your disdain for the repetetive nature of the rags, in fact my subscription list is rather short. Do yourself a favor and see if you can find a copy of The Varmint Hunter Magazine someday, likely at Barnes & Noble or like book store. You might find some new trash between the pages. Beware of imitators BTW. My other subscription is Double Gun Journal, something that is assuredly NOT repetitive.

DD, maybe I'm not making myself clear. I'm advocating QL/QT for its educational value, although it has much practical value as well. I've found it to be quite accurate, given all the variables we deal with in reloading.

The last periodical I subscribed to was "Precision Shooting Magazine" - the benchrest rifle shooters mag. Actually, it was quite good, but expensive as is the sport.

No, you are quite clear on that. Does it contain turorials/text that explain the science of IB in detail, or does it just do the calculations and leave one to infer how it arrives at the answer?

One bit from the article I found interesting, is the close correlation the author assumes (claims or otherwise?) between loaded pressure and barrel life. Has anybody ever quantified this in any way??
- mike

mho, it's a "commonly accepted" truth, going back to the writings of Hatcher and Powley. Barrel life decreases with case size and maximum pressures.

The only fly in the ointment is that some believe light for caliber bullets burn throats faster than heavy's. I don't find the supporting logic convincing. FWIW, Dutch.

I've heard this too. Fast magnums pushing light bullets is allegedly harder on the throat.

DD, yes, tutorials come with QL/QT along with considerable explanation.

Very good then, I'll check into that when I dive headfirst into IB.


Regarding the comments about throar wear, McPherson has valid reasons for what he wrote. You may contact him for discussion via VHA online, a feature open to association members. I do not care to get into an online debate on the subject. You may disagree with his thoughts on the matter, but he is very well armed on the subject.

Doc....I've know Mic for sometime and he is one of the more interesting "gun-characters" you will run across.

Knows guns, ballistics and shooting inside and out and can express himself with the best....he would be a lot better know and appreciated but like many of us, he doesn't "suffer fools kindly" and that includes editors or the gun magazines.

DD, here's a good example of how QL/QT can be used to get a TRUE insight into cartridge comparison. I've run QL - 270 vs 3006 - for 150 gr Nosler BTs in 24" barrels loaded to the same PSI. You'll see there's not a nickels worth of difference in performance, everthing else being equal. Here it is:

Cartridge: .270 Win.
Bullet: .277, 150, NOS BalTip 27150
O.A.L: 3.340 inch or 84.84 mm
Barrel Length: 24.0 inch or 609.6 mm
Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 65000 psi, or 448 MPa
or a maximum loading ratio or filling of 115 %

These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window. C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand that all of the listed powders can be unsuitable for the given combination of cartridge, bullet and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations. USE ONLY FOR COMPARISON !

Powder type/%Filling/Charge -grs/Vel.-fps/P max

Norma MRP/106.1/59.5/3073/65000
Reloder-25/113.2/61.2/3072/65000
N560/104.5/59.3/3065/65000
RamMag/108.8/63.3/3060/65000
MAGPRO/107.3/61.8/3054/65000
Retumbo/115.0/62.8/3050/62433 (great load)
IMR 7828/109.3/58.7/3048/65000


Cartridge: .30-06 Spring.
Bullet: .308, 150, NOS BalTip 30150
O.A.L: 3.340 inch or 84.84 mm
Barrel Length: 24.0 inch or 609.6 mm
Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 65000 psi, or 448 MPa
or a maximum loading ratio or filling of 115 %

N560/115.0/68.4/3198/64842 (great load)
RamHunter/106.3/64.5/3162/65000
Norma MRP/115.0/67.7/3160/60208
7828 SSC/115.0/67.3/3159/64847
Win760/103.9/62.5/3156/65000
N550/103.9/61.8/3151/65000
XMR 4350/108.6/61.9/3149/65000
IMR 4350/108.5/61.2/3147/65000
IMR 4831/112.0/63.6/3138/65000
WXR/115.0/67.3/3136/61255

Now check external ballistic performance, accounting for the difference in BC, and you'll find they're essentially identical at 300 to 600 yds. Happy and safe reloading and hunting - AIU

DD, here's the external ballistics for the two guns. As you can see there's no practical difference. If one understands, internal and external ballistics this all makes good sense. Indeed, the 270 has often been touted as a flatter shooting gun than the '06, but this not true, when the guns are loaded equally. In fact, given current technology, the 150 NBT is slightly flatter shooting in the '06 than the 270.

Yards/fps/ft.lbs./trajectory in.
270 150 gr. NBT/BC=.496/muz.vel=3075
000/3075/3149/-1.5
100/2880/2762/+3.3
200/2693/2416/+3.9
300/2514/2105/0.0
400/2342/1827/-10
500/2177/1578/-26.1
600/2018/1356/-49.5

30-06 150 gr. NBT/BC=.435/muz.vel=3200
000/3200/3410/-1.5
100/2972/2941/+3.0
200/2755/2528/+3.6
300/2549/2164/-0.4
400/2352/1842/-9.6
500/2163/1559/-25.4
600/1984/1311/-48.3

In general terms I kinda knew that. Don't doubt the programs can work comparisons in regard IB/EB by the yard but this isn't what I meant by understanding what is going on in the boiler room. I have questions regarding shock wave propagation(primers/charge burn), the things that inflence quickness, powder coatings, etc., in fact I have a lot of mental puzzles about virtually everything that occurs betwixt firing pin and muzzle. The facets of EB that I am trying to unravel primarily relate to the interrelations between gyroscopic stability, overturning moments, form and transonic turbulence at long range, or at least at the ranges where the nexus of these issues is found. As indicated previously my focus has been primarily on EB, the reading on the subject is a labor of sorts, and understanding the math is a bit of a challenge to me. No Pentium chip between my ears, nosiree!

Aside from the other items I mentioned above there are aspects of chemistry and metalurgy attendent with IB and I know squat about those subjects. These are the things I had in mind when I said I wanted to understand interior ballistics. I've no doubt it will be as mind numbing a journey as some parts of my trip with exterior ballistics, hopefully when the light comes on at the end of the trail it will be worth the effort.

Regards,

Dan

DD, what's the practical utility of knowing all that "stuff?" Do you make your living in the industry as a ballistics engineer? Unless you have a laboratory to measure these "things" you describe and plan to manipulate them in some benificial way, why even bother?

quote:

Originally posted by Ackley Improved User:
There is a great deal of BS published in the gun magazines - remember they're in the business to sell magazines and advertisements. Who buys the advertisements? - The gun/ammo manufacturers, who want favorable articles!

I read a magazine awhile back (Gun Test Magazine maybe?) that a fellow gun enthusiast lent to me. It had an unusual format in that they did not accept ANY advertisements from anybody, period. If I remember right the magazine subscription was relatively spendy ($70 a year I think) but the articles were fairly true, as far as I could tell and the subscription cost paid for the publishing, not the advertisers.

They actually went out and bought 10 or 12 30-’06 bolt rifles made by different manufacturers right from dealers to test, instead of having the manufacturers send them rifles.
Can you say no ringers?

They put the same make and model scopes (again bought right over-the-counter) on each and used the same factory ammo bought locally. 6 or 7 different guys of varying experience shot each one with all the different ammo and were not told which ammo/gun combo they were testing.

It was amazing the results they obtained.
The LEAST expensive rifle out of the box (by $150) was the most accurate overall and except for a couple rifles with a few types of ammo that were close, it was the most accurate ultimately also.

It made me wonder how many times the gun manufacturers may have sent ringers for the magazines to test. Ignoring author bias, this alone could change sales.

If anybody knows the name of this magazine, let me know.

Oh yeah, good article...

quote:

Originally posted by Dutch:
mho, it's a "commonly accepted" truth, going back to the writings of Hatcher and Powley. Barrel life decreases with case size and maximum pressures.

The only fly in the ointment is that some believe light for caliber bullets burn throats faster than heavy's. I don't find the supporting logic convincing. FWIW, Dutch.

A friend that has more schooling than I and reads WAY TOO MUCH told me that light for caliber bullets move faster down the barrel initially and consequently use the first part of the bore for the initial powder combustion. A heavy bullet resists moving more so as to hold initial high temperature combustion in the case more.

I don't know...

Factors determining barrel life are easy to understand. With each firing, the inside of the barrel is exposed not only to bullet friction but also to extreme heat, expanding gases, and powder particles. The first is negligible, but the latter is very important. Each firing is like exposing the inside of the barrel to a blast form a blow torch with powder "sand" in it, and the intensity of the effect is greatest at the throat, which always wears out first. The smaller the bore, the smaller the surface area exposed, and the greater the effect of each shot. The more powder, the more heat, and the more powder "sand" effect. Hence, overbore guns (the big mags) like 264 WM wear out relatively quickly, whereas underbore guns like 308 wear out relatively slowly. Another very important contributor is how quickly you fire the weapon, because rapid firing allows the barrel the heat up - a condition that "softens" the steel and intensifying the overall effects of firing. If you worried about barrel life, don't shoot your big mags very often and always let the barrel cool to RT between groups.

D'Dan,

When you do come to understand the almost infinite puzzles associated with internal balistics, please sum it up in 500 words or less for those of us less astute. (BIG GRIN)

I would feel great pleasure in simply knowing why some powder burn rates swap places depending on which cartridge and bullet combination they are being used in. To be able to predict those transitions would amount to ecstacy of an obscene nature.

Ah, the pursuit of knowledge for no purpose other than the satisfaction of greater understanding!

ID, I know what you mean. In my '06 AI, Re19 acts as slow as Re22 when using 165 gr. NBTs. Although QL will give you a rough idea of where to start, one needs to test the predictions, while watching closely for pressure signs.

Idaho Shooter, that's a tall order, can I get a few extra word credits if I hyphenate a lot? The answer to your question is found in the term 'quickness' rather than burn rate. They are not the same thing and as you note 'quickness' is a chimera, changing noticably due to small influences and large. I know this, but cannot adequately explain it at the moment. This is one reason I will go back to 'school' down the road a ways. Will send you my autographed short story after graduation.

AIU, well what is the reason? To me it is good enough that I know things concrete. Epiphany comes quickly on the heels of knowledge. One of my pet progect ideas involves the use of sub-caliber munitions at hyper-velocities from shoulder fired weapons, so maybe I do need to understand some of that jazz, what do you think? On another level I might refer to your comments above about barrel life and say I do not agree with your assessment, then explain why with enough documentable fact to show you why it is not the way you think. Your thoughts reflect conventional wisdom but not the reality I know. As I stated above however I do not care to debate the matter in this forum.

BTW, I saw an article today in a magazine I once held in higher regard wherein the author claimed to be having 1/2 MOA accuracy from a Marlin 717/HM2. His basis was ~.65" groups at 50 yards. For the most part you are correct about the quality of gun journals. But then they are not marketed at people like you and me, they are for the neophyte or occasional buyer/hunter. Even for all of that there are a few writers that DO know what they speak of and are not industry hacks. The previously mentioned VHM, Precision Shooter, Double Gun Journal and perhaps a few others are targeted at higher levels of expertise, and in fact would probably bore an 18 year old deer hunter to death.

Regards,

Dan

DD, what are your thoughts regarding barrel life? I'd be interested in reading about them. When you claim "great knowledge" and then don't back it up, you know what that sounds like....

I don't claim great knowledge, though I do pursue it. Consider that I have not answered your challenge thus you are right and I am a pussy.

Incidently, Digital Dan mentions the Varmint Hunters of America (VHA). I also recommend the magazine. The articles range from very technical to just plain huntin stories. I have been past the clubhouse located "somewhere in the Dakota's" It is actually a few miles west of Pierre, SD. I am a member of the club, but I have never been to the clubhouse. I plan to remedy that in the future. They have a really nice range and lots of activities throughout the year. Check out varminthunter.org

One very significant factor in barrel erosion is the temperature of the gases. This in turn is primarily a function of peak pressure. Modern cartridges often have cases large relative to the bore giving high, fat pressure peaks, and this leads to bore erosion. Powder types has another effect on erosion, but I believe I'm correct in saying the temperate/pressure effect is the biggie.

I feel QuickLoad is the best internal ballistics tool on the market, but it contains too many simplifications to be considered reliable; primer and bullet engraving effects are ignored. However, as AIU suggests, it is a great tool for learning the trends in internal ballistics.

Most of the important trends in internal ballistics can be found with the Powley Computer. It tracks well the outputs of QuickLoad; it is free. It will not tell you about reduced charges and the like, but it does a decent job of predicting performance with full cases, and its pressure computer allows one to estimate the performance of lower pressures as well.