# Chronograph??



## Huge29 (Sep 17, 2007)

Do all of you guys use chronographs? I am getting tempted...
If so, this one sounds decent, doesn't it? http://www.amazon.com/Shooting-Chrony-7 ... hronograph
From what I have read, the remote display is a must to still be able to read it while it is out 10-15' away.
Which other things should I consider? Do you find they help? From what I understand, just use them to see when you are no longer getting faster with more powder (within the prescribed range, obviously)?


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## Al Hansen (Sep 7, 2007)

Never used one but the guys that do swear by them.


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## gwailow (Jan 20, 2008)

If you want precision accuracy, you need a chrony to accurately determine your ballistic drop. It's also real good to help you determine how accurate your hand loads are and how well your powder of choice metered out. Chrony's are great if you're looking for more than just "good enough" out of your rifle and hand loads.


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## Mojo1 (Sep 8, 2007)

I have one and I mainly us it when doing load development, I like to know how fast my stuff is going.


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## DallanC (Jan 13, 2009)

Yep, I have a crony... they are very useful.


-DallanC


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## longbow (Mar 31, 2009)

I have one and use it for all my loads. Honestly, it's not so important for close shooting but when you start shooting at longer ranges it's important to have close, consistant velocities. Considering the parabolic curve of the bullet's flight, at longer ranges, you not only shoot higher/lower but you'll also drop in closer/farther which causes a vertical spread in your groups.
And it's fun to know how fast your bullets are screaming.


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## Bo0YaA (Sep 29, 2008)

DallanC said:


> Yep, I have a crony... they are very useful.
> 
> -DallanC


+1 great tool.


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## gunplay (Apr 28, 2008)

Wouldn't be without one for load development.


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## Frisco Pete (Sep 22, 2007)

> From what I understand, just use them to see when you are no longer getting faster with more powder (within the prescribed range, obviously)?


Well there is a lot more to using a chronograph that that bit of misconception.
And BTW, the very best chronograph of all is available again for a short time - The Oehler 35P. Oehler is the leader in chronographs and in the past most data you saw was chronographed using them. They have a 3rd screen that helps detect bogus errors.
I would also look at the RCBS chronograph before the Chrony. But any chronograph is better than no chronograph.

*People who don't use a chronograph are really just fumbling around in the dark*. You don't realize how much so until you actually get one. Yes, you don't absolutely NEED a chronograph to reload ammunition. For years reloaders have "guess-timated" velocity based on extrapolation of what the reloading manuals say.

One thing you will learn from chronographing is that you really don't know what velocity a load is going to produce from your firearm until you chronograph it.
There are a lot of reasons for the velocity variation between published velocity and the velocity you receive from your won rifle or handgun. Firearms are different in terms of throating length and other dimensions in the chamber and bore. There is a considerable difference in cartridge brass thickness and capacity. The performance of each component might vary slightly from one lot to the next. The design of the bullet can affect pressure and hence muzzle velocity. While you can speculate all you want about the effects of various components or a change in barrel lengths, for example, you really don't know what the effects are without a chronograph. A chronograph cuts through all the speculation and gives you a bottom line figure exactly what your bullet's velocity is.

When loading what seemed to be a fairly hefty load for the 150-gr 7mm Rem Mag the manual said I should be getting X velocity. However, in real life I was getting the same velocity as a good .280 Remington load. Not hardly magnum stuff. Of course the down side here is that all along you thought you had this fire-breathing Hammer-of-Thor Magnum and heaped derision on your fellow hunters with their .270s and '06s, until you just found out that you are shooting basically the same!

Or you pick a factory load - say the Rem/UMC 55-grain MC Value Pack load for your AR15 with a NATO chamber. Remington claims a velocity of 3240 fps from a 24" barrel (SAAMI chamber). Can you base your ballistic drop on this velocity figure in your AR?
No. If you have a chronograph and shoot 10 rounds of this ammo thru your sky screens from your 20" barrel AR15 you will find that the average velocity is 3063 fps (_in my personal case_). Which obviously is 180 fps low. What if your AR15 is a popular 16" barrel version? What is your drop now? Do you guess a loss of 25 fps per inch of barrel length (200 fps), or do you want to know?
You shoot it over the chronograph and see that it delivers an average of 2941 fps for 10 shots (_again, in my personal case_).
If you are using something like a Nikon scope and Nikon's Spot-On ballistics app, you can then dial that figure into the app and get the most out of your scope.

Or you use the American Eagle XM-193 55-gr 5.56 Ball ammo that is a NATO-pressure military load and thus loaded to higher-than-SAAMI .223 Rem specs. - what then? The same?
No. You test it and it chronographs 3242 fps from your 20" AR15 and 3118 fps from your 16" AR15 (_actual personal results_).

Given a specific bullet, the downrange performance of a load - everything from drop, to wind deflection, to energy, to expansion performance - is dependent upon muzzle velocity.

Obviously a chronograph tells us the velocity of a given load, but what are the other benefits of using a chronograph during the reloading process and how can velocity tell us anything about pressure? Aren't those signs revered in handloading lore and written in the reloading books good enough for me without messing with this technical stuff that costs more money?

As an example, take the data from the Hornady manual: A Max load of the popular H-335 for their 55-grain bullets [V-Max, SP, FMJ-BT] is listed as 23.2 grains @ 3100 fps (24" bbl). But Speer says Max is 26.0 grains @ 3092 fps (22" bbl). So where do you load to? One constant is the velocity: 3092/3100 fps. At this velocity both data sources agree that this is a maximum WORKING load (i.e. safe within SAAMI pressure guidelines). Once again - without a chronograph what is your load work-up goal? Or should you just load low? And all that fouling when loaded "safe"! H-335 is a high-performance ball powder made to burn correctly within a certain pressure range that it was engineered for as a military ball powder. Are we loading it in the proper working range? Will the deterrent coating on the powder burn off cleanly?

Basically ALL handloaders worth their salt have been brought up to gauge pressure signs based on primer appearance etc. What we don't think about is that those signs only appear *AFTER THE PRESSURE IS ALREADY TOO HIGH*!
Gun writer and handloading guru John Barsness reports that in his testing experience: "I worked up loads in 3 different cartridges (.22 Hornet, .270 Winchester and .30-06) using all the old-fashioned methods: bolt lift, primer appearance, measuring the case head, etc. Then I had the same "maximum" loads tested at the Western Powders lab. If I remember correctly, in the .22 Hornet the pressures of my handloads were about right, in the .270 they were too high (around 68,000 psi), and in the .30-06 a little low.

The worst thing you can count on is primer appearance. How much primers flatten, or how much the metal "cups" around the firing pin indent, will vary considerably for reasons that don't have anything to do with pressure.

If the head of the case starts showing ejector marks from brass flowing into the ejector hole or slot, then you are running around 70,000 psi already."

So just how will owning a chronograph help you here and answer our conundrum about what goal for our magical .223/55-gr H-335 load?

*THINGS YOU SHOULD KNOW ABOUT HOW VELOCITY RELATES TO PRESSURE:*
*Or finding the practical maximum (or working) velocity*

"*Muzzle velocity for a selected load is a function of the mean effective pressure and the barrel length.*" - _Lloyd E. Brownell, Ph.D. - Firearms Pressure Factors, Wolfe Publishing Co_.

"Because *velocity is the by-product of pressure*, a chronograph can, albeit indirectly, give you an insight into pressure being developed by a given load. While a chronograph is no substitute for a pressure gun, your velocity data can alert you to potentially dangerous pressures before you're stuck trying to super glue your receiver back together. 
Is there really any objective benefit, beyond entertainment, to knowing the actual velocity of a given load in your gun? You bet. A chronograph can provide you with an insight into the interior ballistics (pressure) of your loads, guide load development, provide you with the information needed to calculate your optimum zero and field trajectory and ensure that you have loaded a given bullet to a proper velocity for expansion on game." - _Barnes Bullets #2, Ronin Colman, "What Do You Do With A Chronograph?_"

*The best predictor of pressure is a chronograph*. If you're getting muzzle velocities noticeably higher than is common for that cartridge, powder and bullet, then your pressures are higher than they should be. It's that simple. If you work up loads using that rule, then you don't need to look at fired cases, because the pressure will never get high enough to form ejector-hole marks on the case heads or blow primers.
...*next to real pressure equipment, a chronograph is the best guide to excessive pressure for the home handloader.* *There are no "magic barrels" that allow another 100 to 200 fps!* - _Handloader, June 2004, "More Pressure Experiments", John Barsness._

A chronograph does many things for the handloader. Obviously it indicates just how fast the bullet is going, but it also tells us how consistently the bullet leaves the muzzle. This may or may not have any bearing on accuracy, at least at "normal" ranges, and holes in the target are the ultimate measure of consistency. But when things are perking right, the chronograph is one more indicator of consistency.
More importantly,
Think of the firearm as a single-stroke internal combustion engine with an expendable piston, the bullet. Everything else being equal, a certain average pressure will always produce the same velocity. This means that, *everything else being equal, if the velocity changes so did the pressure*... - _Handloader Magazine editor Dave Scovill_.

My yardstick for pressure is a combination of chronograph readings and primer pockets... The speed readings are easy: *don't expect to get much more or much less than what you see published*, and pay close attention to the rifle barrel specs the data came from... - _GUNS Magazine, May 2010, "Reloading Puzzles & pieces thereof", Glen Zediker_.

*One of the most valuable applications for a chronograph is in keeping loads safer*. Loading manuals provide a guide, generally suggesting a starting and maximum load. These load recipes are determined by careful loading and pressure testing. Maximum loads are based upon industry standard chamber pressure criteria. *Generally speaking, with a given set of components, the higher the velocity, the higher the chamber pressure that is required to produce the velocity. If one of your loads produces velocity in excess of what a loading manual indicates, you can also assume that the pressure is in excess*. If the velocity of one of your loads equals the maximum listed velocity in the loading manual (with a comparable barrel length), it's prudent not to exceed the powder charge level you're using, even though the quantity of powder you're using might be less than what is suggested as the maximum quantity in the manual. - _Accurate Arms Loading Guide #1 - Chronographing Metallic Ammunition - Rick Jamison._

So with a chronograph I am able to compare my loads with factory (_read: safe-pressure_) loads that have been shot from my particular rifle or handgun and work up to that velocity if I desire. Or at least compare them to what an average of reloading handbooks are getting from that load as far as velocity. So it works as an *AID OR ADJUTANT TO OTHER ESTABLISHED PRESSURE SIGNS* and can often be your *FIRST* warning sign. It can also answer some questions on what a load is doing that seems somewhat odd when compared to what was expected in the reloading manual.

*SOME EXAMPLES OF USING A CHRONOGRAPH IN LOAD WORK UP:*
WARNING: The examples given below are based on data shot with a Hornady 55-gr SP bullet, a particular lot of H-335, LC cases, and Rem 7 1/2 primers in those particular rifles - They are given as examples of what you might encounter rather than as a definitive loading data for YOUR components and rifles!

Therefore, armed with the data in the loading manuals for our planned H-335 55-grain Hornady SP bullet .223 load we see that 3100 fps is a safe SAAMI pressure load in a shorter leade SAAMI chamber. Say we are loading for a SAAMI chamber bolt action .223 22" bbl. like the ones used to shoot the data. In working up we find that 25.5 grains gives us around 3100 fps and 26.0 grains gives us a 3160 fps average. We can now match factory pressure/velocity and have never gone overboard to where traditional pressure signs appear.

Say we then load for another 22" barrel bolt action .223 and try the same thing. In this other rifle we find that the top 26.0 grain load gives us only 3060 fps. So therefore we can tailor this load and feel good about not being excessive on pressure in this particular rifle (_again, base on actual experimentation_). The Hornady load data as far as _max charge weight_ was really too low in our rifles, but the _velocity_ of 3100 fps and hence _pressure_ indication can still be relied upon in our case. And the Speer data was much closer to our experience.

We decide to load for our AR15s now. We bear in mind that the barrels are shorter and the chamber is a more pressure-friendly 5.56 NATO that gives a little more run for the bullet to bleed off some pressure before hitting the lands and causing a pressure spike.

Remember our data chronographed using both SAAMI-spec 55-grain and hot NATO-spec X-193 55-grain? 3063 fps and 3242 fps respectively. Now we aren't using new brass with the primer crimped in _ala_ 5.56 M-193, but the gun is good for that. So we seek something a bit less. In this particular case when we get to the max test load of 26.0 grains we get 3153 fps. At this point we see that our load is above that of the SAAMI .223 Rem load but still significantly below that of the NATO 5.56 load. There are none of the traditional pressure signs associated with this 26.0 grain H-335 load. Therefore we can decide whether we will use this 26.0 grain load or go with one of the lesser work-up charge loads. We are dealing with facts and known quantities to make our decision, rather than the old guess-timation stuff.

We try the same work-up stuff in our 16" AR15 NATO chamber and find that the SAAMI 55 load shoots 2941 fps while the M-193 55 NATO load shoots 3118 fps. Our 26.0 grain H-335 maximum chronographs at 2922 fps. The results are slightly different than in our 20" AR but again we can have an intelligent basis on whether to use the 26.0 grain load or not. In this case we may decide to use it and with the data shot in 4 different rifles we can decide how this load stands overall.

But realistically, at no time are we using the chronograph "just... to see when you are no longer getting faster with more powder (within the prescribed range, obviously)" because that is not how it works, nor is _always_ a reliable pressure indicator.

Working up loads for handguns can even be more critical as they take less pressure than a rifle, yet semiautos have specific power/pressure needs for function.

Say we are working up a practice load for our 9mm autopistol to replicate the 115-grain FMJ-RN we use from the factory. We chronograph our factory ammo and come up with:
Federal Champion = 1099 fps; Sellier & Bellot = 1068 fps.
We then load our chosen 115-grain FMJ-RN bullet and decide to use Alliant Power Pistol which was developed specifically for the 9mm Luger and recommended by Hornady. 6.0 grains gives us 1151 fps and 6.5 grains gives us 1214 fps (Hornady maximum is 6.7 grains @ 1250 fps). Obviously we are a bit over the factory stuff, but not our data source. Considering that in modern guns we can also use higher pressure +P ammo, we can feel good about our maximum. In our particular case, however, we decide to stick with the load that is closest to the factory practice ammo velocity/pressure, so we pick the lighter 6.0-grain load for our practice/target/plinking. Again we are working from knowledge instead of guess.

And within the parameters we establish, we can then fine tune our load for accuracy if desired. We can also avoid the traps of the old reloading saw that accuracy loads are _always_ less than maximum, or that accuracy will drop off when pressure gets excessive as this doesn't always happen with modern powders.


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## Huge29 (Sep 17, 2007)

Thanks Pete! That was an earful of great stuff!


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## Briar Patch (Feb 1, 2010)

Frisco Pete said:


> ...
> Well there is a lot more to using a chronograph than that bit of misconception.
> ....


+1

Thanks for taking the time to put that post together Frisco. I always come away better educated after reading your posts.


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