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Sierra Bullets
Rifle Magazine
April - May 2000
Volume 35, Number 2
ISSN: 0017-7393
Number 204
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I bought my first chronograph over 20 years ago from the Custom Chronograph Company, which has spent its life moving around tiny towns in Washington state. This was back when many chronographs still operated off a binary-switch system, and photoelectric light screens were just coming into use. I bought the unit for two reasons: It was the cheapest ($89.95) “light-screen” model listed in the 1979 edition of Handloader’s Digest, and the company gave me a good discount, though I’d published only a few rifle-related articles in various obscure magazines. These days $90 doesn’t sound like much, but back then you could buy a box of .30-caliber Nosler Partitions for $10, so any discount meant a lot to a starving university student.

My Custom Chronograph Model 600 had a rotary switch with 11 stops, each marked by a number. After the shot I turned the switch through each stop; if a red light blinked on I recorded that number. Four would eventually light up, say 1421. I’d look up that number in a booklet and find my bullet had traveled 2,843 fps. Then I’d reset the chronograph by switching it off and on and shoot again.

This might seem a tedious process but was light-years ahead of the alternative: break screens. Used for decades before the advent of photoelectric screens, most consisted of aluminum foil attached to paper backing, the foil forming horizontal lines, spaced closely enough that a bullet would break a line somewhere. After each shot both front and rear screens had to be replaced, and you couldn’t shoot groups at the same time, since the screen blocked the target. Along with light screens, the Custom Chronograph Company included all the gear for break screens, probably because nobody wanted them anymore. Aside from a single test the first day I tried the chronograph when five Long Rifles from my old Marlin .22 averaged exactly 1,179 fps over each type of screen, I never bothered with break screens again.

Few shooters owned a chronograph in those days. I did my shooting at the popular Deer Creek Range east of Missoula, Montana, and never saw another range member using a chronograph, though a few asked to use mine. The first was a guy with a .357 Magnum revolver. He took three shots over the light screens, each indicating his 158-grain handloads were going about 1,300 fps. He’d assumed they started 100 fps faster, so this almost ruined his day. After some grumbling he moved as far down the firing line as he could, and probably kept on writing “1,400 fps” on the labels of his .357 boxes.

I experienced the same disappointment with some long-treasured loads. My small collection of centerfire rifles included a .243 Winchester and .270 Winchester. The .243Õs deer load consisted of the 105-grain Speer spitzer, 41.5 grains of IMR-4350 and CCI 200 primers in Winchester cases. The top load listed in the just-published Speer Reloading Manual Number 10 was 42.0 grains for 2,995 fps (also using Winchester cases and CCI 200s), and Speer’s Ruger Model 77 test rifle had a 22-inch barrel, just like my Remington Model 700.

Five rounds fired over the photo screens averaged a little less than 2,800 fps. This obviously wasn’t right, so after letting the barrel cool I tried five more. These averaged closer to 2,750. How could the dozen-odd deer shot with the rifle have died from bullets plodding along like that?

My faithful .270 Winchester produced the same disappointment with 58 grains of H-4831 and the 150-grain

Hornady. The year before I’d shot this load at 300 yards, after carefully sighting in 3 inches high at 100 yards. Four shots (the last in the box) landed in a neat 1.25-inch group, centered 2.5 inches low. (This was a very accurate rifle, three-shot, 100-yard groups with the same load often measuring 1Ú2 inch.) According to the trajectory tables in my Hornady Handbook Vol. II, this meant a muzzle velocity of just about 3,000 fps.

But the chronograph said the load only started at about 2,850 fps. Just what was going on here?

Nothing but an old disease, known among psychiatrists of the loading bench as “Handloader’s Optimism,” known as HO for short. (When chronic, as is frequent, the condition is called HO-HO-HO). Like most handloaders who don’t own a chronograph, I’d “pored” over various manuals and picked the highest velocity given for “my” loads.

Each load had killed a pile of game out to 350 yards, as far as I’d ever shot at anything. Normally both rifles were sighted 3 inches high at 100 yards. Out to 300 I just held right on and the bullets landed close enough to where I aimed, but on the few animals taken over 300 I’d held slightly high and killed everything neatly. So what did it matter that they started a couple hundred fps slower? They worked!

It took over a decade for that lesson to insinuate its way into my brain. Back then I felt compelled to work up loads achieving 3,000 fps, using the 100-grain Nosler Solid Base in the .243 Winchester and the 130-grain Sierra in the .270 Winchester. They didn’t fly noticeably flatter or kill deer quicker, but I felt better, like somebody in a medical experiment who’s given a sugar pill instead of the real thing.

Since then I’ve encountered other velocity-impaired shooters, who seem to think super-speed bragging rights are the only reason for ever shooting across light screens. A buddy called one day, not even saying hello, just crowing “3,192!” This was the supposed velocity of his favorite 130-grain, .270 load, just chronographed over a friend’s Oehler. On closer inquiry I found 3,192 was not the average velocity of the load, but the fastest bullet in a five-round string. I suspect, like my acquaintance with the .357, he writes the HO-HO-HO number on his boxes of .270 loads.

More sophisticated chronographers come up with other fictitious numbers. Perhaps the most widely publicized is standard deviation, which to some not only bestows bragging rights but is equivalent to the Word of God. According to one heavy dictionary, standard deviation is: “Statistics: A measure of dispersion in a frequency distribution, equal to the square root of the mean of the squares of the deviations from the arithmetic mean of the distribution.” Got that?

Having spent some of my university life trying to make mathematical sense out of field work, I am somewhat familiar with the odd science of statistics, enough to agree with whoever said, “There are three kinds of lies: lies, damned lies, and statistics.” (Benjamin Disraeli sticks in my mind, but my wife thinks it may have been William Gladstone. My 1955 edition of the Oxford Dictionary of Quotations does not enlighten. If you know, please write me c/o Rifle, 6471 Airpark Drive, Prescott AZ 86301. This is trivia of vast importance.)

A few numbers-crunching handloaders have proposed standard deviation (SD) as a measure of accuracy. Some even suggest that a load with a low SD has great potential accuracy, even when it sprays bullets like confetti. This notion has grown popular enough that many chronographs include an SD function, including the inexpensive Shooting Chrony, which has done more to bring the realities of bullet speed to everyday shooters than anything else. I am on my third chronograph now, and second Chrony, for reasons that shall be explained later. My latest model has an SD function.

How useful is it? Let me explain. After three or four years of using this Chrony, I’ve found about the same correlation between standard deviation and accuracy as between asphalt and trout. Here’s a typical example, straight from my own .270 Winchester. While trying out some 130-grain Hornady Spire Points one day, over a standard load of 60 grains of H-4831, I first shot three times, getting a group of 1.66 inches with an average velocity of 3,015.66 fps and an SD of 4.99. The SD was so low that I shot up nine total rounds of the load. Two more three-shot groups went 1.45 and 1.87 inches. Average velocity for all nine dropped a little to 3,011.2 fps, while SD increased slightly to 10.86.

Since this is normally a very accurate rifle, I tried a half-grain less powder. Velocity decreased, of course, to about 2,980 fps, and SD increased to over 30, which is not considered too good by the statistical “ballistical” crowd. Three, three-shot groups averaged just under an inch.

How could this be? The reason is very simple, and applies to almost all light hunting rifles. Normally a “good-shooting” load involves bullets exiting the muzzle when the barrel is “bottomed out” in its vibration cycle. Essentially, the muzzle is pointed in the same direction each time a bullet leaves. Since the barrel pauses briefly at each end of its vibration, even variations of 50 or even 75 fps (or SDs of 30 or more) often don’t cause groups to grow, but if the bullets exit while the barrel is whipping around in midcycle, even small variations in velocity can result in large groups.

Another thing I have noticed with this handy-dandy SD function is that often one five-shot string of a load will show a very low SD, say under 10. So I try the load again and get an SD of 38, quite high. What does this mean, especially when each group is essentially identical? The answer is, of course, not a thing.

The real statistic applicable to most hunting handloads is not standard deviation but reliability. Do the bullets regularly group into circular patterns, or do fliers mar perfection? Do groups stay about the same size, or does the rifle shoot into .5 inch one day and 2 inches the next? Does the rifle shoot to the same place on Sunday that it did on Saturday?

Standard deviation is indeed a useful tool for ammunition companies that must create consistent cartridges by the hundreds of thousands, but home handloaders who cite standard deviation remind me of a verse from the Oxford Dictionary of Quotations, chanced upon while trying to find that quote about lies and statistics. It was penned by one Winthrop Mackworth Praed, who died at the tender age of 37 in 1839:

 “Of science and logic he chatters,
As fine and fast as he can;
Though I’m no judge of such matters,
I’m sure he’s a talented man.”

 With that we’ll leave standard deviation and go on to the really useful things a chronograph can do for your hunting loads. Most importantly, a chronograph allows a basement handloader to create safe loads. How so? Don’t we need a pressure barrel to find absolute pressures? No, we don’t, because the bullet and powder companies who write handloading manuals use them. While some list pressures, those are interesting but irrelevant to our needs. The important statistic is velocity.

Here’s why. The odds that any given published load, even if duplicated exactly, will create the same pressure in our rifle are probably 100 to 1. There are just too many variations in bore diameter, land width and throat length (not to mention different lots of powder, bullets, cases and primers) to expect 60 grains of H-4831 to produce the 51,700 CUP listed with a 130-grain, .270 bullet in Joe’s Reloading and Cook Book.

But if we build various loads with H-4831 and the same bullet in our .270 Winchester and find the powder charge that produces the same 3,050 fps listed in Joe’s book, we’re on pretty firm ground. Why? Velocity is a very good indication of pressure. It has to be, since it’s the direct result of pressure. While individual .270 rifles may vary slightly, they’re close enough for the same pressure level to produce the same velocity. This has to do with a bunch of “gas laws,” which, since it has been almost 25 years since I last sat in a chemistry lecture hall, shall remain nameless. But given the same powder and bullet, muzzle velocity is indeed simply another measure of pressure.

Here’s how it works in what’s called Real Life. Last fall I had a custom 7x57mm built on a Remington Model 700 action by Lex Webernick of Rifles, Inc. It has a 24-inch Lilja barrel and is superbly accurate, partly because of the fine barrel, partly because of Lex’s gunsmithing skill and partly because it has a short throat. Most 7x57s are still built to accommodate antique 175-grain military loads, even though they’ll never see one, with enough space in front of the chamber to house a Norway rat. This long jump between case and rifling tends to limit the bullets that will shoot well. The half-dozen 7x57s I’d previously owned all exhibited very persnickety preferences. Many would shoot one type bullet into one-inch groups and everything else into 2 inches or more. I’d always wanted a 7x57mm that would shoot a wide range of bullets accurately, and Lex suggested the solution was a more normal throat, so throated the chamber to accommodate a 140-grain Nosler Partition seated to the base of the neck.

This, however, meant that standard 7x57mm loading data, worked up in longer throats, would be invalid. That really didn’t matter to me, since most 7x57mm loading data is wimped down to create a safety margin in old military rifles, so doesn’t apply to modern rifles. Instead I consulted 7mm-08 Remington data, feeling I was on safe ground because the 7mm-08 has about two grains less capacity than the 7x57mm. Any velocity level safe in the 7mm-08 would be safe in a short-throated 7x57. Data from various manuals, and my previous experience, suggested Hodgdon H-4350 would get as much velocity out of the 140-grain Partition as any, while maintaining that velocity in the subfreezing temperatures often encountered during Montana Novembers.

The same manuals suggested 2,900 fps or a little more would be realistic from a 24-inch barrel. From long experience, I knew that long-throated 7x57s will handle 50 grains of H-4350 with 140-grain bullets, so I cut that back 10 percent to 45 grains. A five-shot string produced 2,671 fps. Another grain clocked 2,782, and 47 grains, 2,919. Eureka! Three-shot loads average around 5Ú8 inch in calm air, which is excellent in a rifle weighing under 71Ú2 pounds with its 1.75-6x Leica scope. It’s excellent in any hunting rifle, and the brass has lasted through several firings with tight primer pockets. (So far my experiments with other bullets indicate Lex was right about the throat too.)

A chronograph also assures that bullets will expand at longer ranges. While there’s some variation (see Handloader No. 193, June 1998, for Gary Sciuchetti’s excellent test), most expanding big game bullets will expand readily down to at least 2,000 fps. If you might shoot a pronghorn or deer at 400 yards, a muzzle velocity of at least 2,900 fps with most bullets assures good expansion to that range. With some bullets 2,800 fps will do it. Last fall I hunted whitetails in Arkansas and planned to test a new 140-grain, 7mm-08 factory load. The velocity should have been at least 2,800 fps, even from the 22-inch barrel of my rifle, but the Chrony indicated an average of 2,700 fps, which meant expansion might be iffy past 300 yards. I didn’t plan on shooting past 300 anyway, and the two deer killed were at 75 and 140, but not relying on the catalog numbers made everything a little more sure.

With a chronograph you can also rebuild a favorite handload more easily. Variations between powder lots can easily change the muzzle velocity of a proven handload 100 fps or even more. One year I ran out of my favorite .223 Remington powder and bought two more pounds. Until then this rifle’s favorite load used 28 grains, for about 3,450 fps with the 50-grain Nosler Ballistic Tip. I loaded up a few and found they not only wouldn’t shoot worth a hoot, but they also made lifting the bolt handle a trifle difficult. Lo and behold, the Chrony revealed they were traveling closer to 3,700 fps! I dropped the powder load until the Chrony read 3,450 again, and accuracy was restored. Since then this simple operation has been performed with new lots of a dozen powders.

There are a few little tricks to owning and using a chronograph. I bought my Chronys after my old Custom Chronograph coughed and died one day. I compared Chronys belonging to friends to more expensive models and found them quite accurate. Unlike most other models, the various Chronys don’t require the screens to be mounted on a board, attached by wires to the main unit on the shooting bench. The whole unit mounts on a tripod with the velocity read off a screen on the front of the machine. My present model stores dozens of shots, providing an average anytime I choose. I keep it on an old camera tripod, set up and ready to go in my loading room, which really saves time at the range when compared to more complex models.

This did create one small problem with my first Chrony, which quit working one day while I measured some .416 Remington loads. Thinking the chronograph couldn’t take .416 muzzle blast, I sent it back to the factory with a letter explaining the circumstances. It came back a couple of weeks later with a note saying I should probably store my Chrony where there was less dust in the air, since a bunch had drifted in through the screen slots. After the Chrony people shoveled the dust out the unit worked fine. Duly humbled, I have since placed a strip of translucent Scotch tape across each slot, which does not affect velocity readings. The tape even seems to help on sunny days, which, through reflections off speeding bullets, often cause bad readings.

That Chrony came to a sad end one day. As usual, I was testing several different guns, including a .300 Weatherby Ruger No. 1 and a .41 Magnum Smith & Wesson. Because of the blast of the .300, I’d set the Chrony 25 feet from the muzzle, rather than my standard 15. After shooting the rifle, I picked up the   revolver to test a new load using cast 200-grain bullets. This .41 was sighted in for my standard load using 220-grain Speer three-quarter jackets, but I didn’t think of that, or that the chronograph was farther away than usual. So I was pretty surprised when chronograph and tripod performed a backflip with the first shot. Yes, indeed, I’d plunked my poor Chrony right in the readout screen. Remember, students: Lighter bullets shoot lower in most handguns. So far my new Chrony has avoided both dust and bullets.

What amazes me is the number of supposedly serious handloaders who don’t own a chronograph, when a Chrony can be had for about the price of a cheap 3-9x scope. I know guys who own anywhere from three or four to several dozen expensive sporting rifles, all scoped with at least $300 worth of glass, who don’t have a clue how their carefully crafted ammunition is really performing. The probable reason is that a lot of them have advanced cases of HO-HO-HO and don’t really want to know.

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