Chronograph

[ninosdemente]

Since I started reloading (+1 yr), have not used a chronograph. I have been in the look out for one and found the Caldwell Premium kit for $100 at amazon and other sites.

https://www.amazon.com/Caldwell-Ball...s%2C157&sr=8-1

Is this a good tool to have or one of those that really isn't necessary? I don't know much about these period other than used for measuring velocity. What would one get from these readings in relation when one loads or comparing to book velocity (do know it is not always the correct velocity)? Hope this is not a stupid question. Which as you can tell haven't done much research on the technical part. Any input would be greatly appreciated.

[Bart B.]

First off my bat....... Smart people ask those questions.

No such thing as a correct velocity.

If you use a given load from some source, it'll probably be several fps different than source data claimed. 50 fps or a lot more is possible and common

I never used a chronograph developing loads. Just test group sizes.

Spend your money on good rifles, reloading tools and components as well as learning good marksmanship skills. Small velocity spreads are no guarantee that smallest groups will happen

[Ben Dover]

IMHO, a chronograph is one of the most useful tools you can own.

I've been using Oehler chrongraphs for well over 30 years. If I needed another one today, I think i would get a Labradar.

You really start learning about ballistics when you get a chronograph.

[ninosdemente]

Got it. Thanks for the reply Bart.

[ninosdemente]

Thank you Ben Dover. Do you mind if I ask you what you got from it apart from your understanding of ballistics?

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popshooting445, thanks.

From popshooting445 reply, curious how reliable are chronos in general.

[Ben Dover]

Originally Posted by ninosdemente

Thank you Ben Dover. Do you mind if I ask you what you got from it apart from your understanding of ballistics?

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popshooting445, thanks.

From popshooting445 reply, curious how reliable are chronos in general.

With experience,, you can get realistic estimates of the pressure/velocity curve.

You can tell immediately if your load is giving consistent velocities.

By measuring factory loads as compared to your hand loaded ammo, you can tell how your loads compare.

the chrono will instantly tell you if that $50/box self defence ammo actually surpasses the velocity of standard ammo, or if you've paid extra for a pretty box.

The chrono will show you differences in velocity between different guns with the same loads.

Differences in velocity/consistency with different barrel lengths.

Differences between the performance of different lot numbers of the same powder. Or the same brand of primer.

Do you absolutely NEED one??? No!

But use one for a while and you'll never be without one again.

[ligonierbill]

Good answers here. I suggest that the real "cost" of a chronograph is more in effort than dollars. The consumer optical chronos aren't very expensive, but you do have some setup, and the data isn't worth much without evaluation. Is it worth it? It is to me. But I load a lot of different calibers, many obsolete.

If you are loading common modern rounds for modern rifles, and only a few calibers, not necessary. You may enjoy getting real data for your gun and load, or you may find it a PITA. But there is so much data for, say, 30-06 or 270 or many others, that you can do just fine with published loads.

[ninosdemente]

Ben Dover, thank you for the detailed answer. Very helpful.

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ligonierbill, I only load for .223/30-06 and 6.5 Creedmoor.

[stagpanther]

Do you need one? No...there are other ways of figuring this stuff out. That said, I probably would have blown myself up long ago without constant use of Labradar and Quickload. I feel pretty confident in saying that while it may take time getting up to speed with them I seriously doubt you'll ever consider them wasted money. Every now and then they will also flag a standard published load too which I always double-check.

[ninosdemente]

Seems I will opt out of buying a chronograph for now.

[jmr40]

Unless you're content to use only beginning or mid level loads a chronograph is pretty important. Loading without one is like driving a car without a speedometer, only a warning light that comes on at 95 mph.

I've seen enough testing to conclude that the $100 units are as accurate as the units in 4 figures. The high end versions will work in conditions where the cheaper units won't work, but the speeds the inexpensive versions show are usually within 10-20 fps of what the expensive units show. But under certain conditions the cheap units may not work at all, or you get nonsensical readings which are obviously wrong. I find any of the $100 units are good enough for me. If they don't work under certain conditions I'll just try again another day.

If you look at a book load showing 60 gr of powder should yield 3000 fps with a 150 gr bullet as the max load, then 3000 fps is the important number, not the 60 gr of powder. Without a chronograph most people keep adding powder and comparing group sizes while looking for traditional pressure signs. The problem with that is that traditional pressure signs don't show up until you reach 70,000 PSI, well over where you should be.

Without a chronograph you might incorrectly conclude that your 60 gr load is perfectly safe since it is showing no pressure signs. You could be shooting 3150 fps with 60 grains and still not be showing pressure signs. But you're certainly over pressure.

By using a chronograph you can monitor muzzle velocity as you work up your load. When you start getting close to 3000 fps you are approaching a max load. You may find that some combo's of rifle, brass, primer, and bullet will reach 3000 fps with only 57-58 gr of powder. That is where you stop adding powder.

In other cases you may find that 60 gr of powder is only getting you 2900 fps with some rifles. Technically it would be safe to keep adding powder over the book max of 60 gr and it would be safe in THAT rifle. I strongly advise against this because those loads could end up in another rifle where they could be dangerous. You're just going to have to accept that 2900 fps is all that rifle is going to do with that powder and bullet.

I don't worry so much about the exact speeds I'm getting. Some people try to use them with online ballistics programs to calculate drops. But those numbers are only good enough to get you close, you still have to actually shoot at those ranges and see what happens.

You have to also consider barrel length. If the load data is for a 24" barrel, and you have a 22" barrel then I'd consider 25-50 fps less than 3000 fps as max in that rifle.

Once I'm satisfied that a certain load isn't going to be over pressure I may tweak the load some by reducing powder to see if accuracy improves.

[stagpanther]

I don't know, I would say the $700 or so you'll spend for both the labradar and quickload are about the best investments you can make in learning to reload--short of being ninja shooter like only a few people here are.

[RC20]

My take is closer to Bart B than anything.

And if you are going to get a Chrono, then the Labradar (and at $500 that puts me right back with Bart B.

Why?

I shot mine once (creased it). Ok but too close.

then it quit working much latter. No reason, one day fine and the next trip no.

[Targa]

I would like a Labradar for indoor use but since most of my shooting is outdoors I am more than happy with this https://www.amazon.com/Competition-E...4895431&sr=8-6

Running test batches of my reloads are as important to me as the reloading press, I try to run factory rounds through it then run my reloads through it for a comparison.

[Don Fischer]

Wonder how we ever got along before we could all get chronographs? I like mine, has a balistic program in it and I can set the trajectory about anyway I want! Mine ever wears out, I won't get another. It does not make me a better shooter, does not make me a better reloader. It does not make my ammo any better at all! Every thing I need to know about my load's I can find out by shooting.

[RC20]

Proof is in the group!

[bamaranger]

My chrono, a very affordable ProChrono, makes a liar out of me on a regular basis.

Some mid range .44 mag handgun loads that I felt sure were making 1000 fps, were running only about 870fps. A heavy .45 acp load that I felt sure was making near 850fps was making a LOT less. A 130/.270 load that was supposed to be doing 3000 fps was notably under 2900.

Accuracy is an element we all strive for, but so is velocity, or a velocity range. My chrono tells me where I'm at on the power curve.

[Unclenick]

I use a chronograph to choose primers. I take the load and for each test primer I run ten with the powder back over the primer and ten with it forward over the bullet. The primer that produces the lowest average spread is igniting that charge weight in that cartridge and bullet combination most consistently, so I choose it.

I use a chronograph to adjust for changes in powder lots. I keep back enough of the old lot for at least 30 rounds. I fire those and (after a pressure confirming work-up) the same number of rounds loaded with the new lot to that same charge weight. I compare the mean velocity values. I change the charge of the new lot in inverse proportion to the ratio of those two velocities and check for a velocity match. If the matching velocity charge weight differs by more than two percent, I additionally model both in QuickLOAD to get matching velocities by changing the burn rate for the new lot, and then adjust to match barrel times rather than velocities, as that holds me closest to a sweet spot.

I use a chronograph to determine the ballistic coefficient for a cast bullet I have no reliable published number for. In the last couple of years, I've used the Labradar for that, as it supplies velocities at the muzzle and four other ranges for each shot. I fire 30 rounds and see which one produced the highest BC and figure that is the one that had the least initial yaw and so its BC better represents what will happen with the bullet as it gets beyond the Labradar's range.

(I used to use conventional optical chronographs for the above. I have two, an Oehler and a CED that track well, and I'd set the Oehler at a close range and the CED near the target and use their reading pairs to get velocity loss over the range between them. The Labradar is much quicker to set up and use and the only way to get multiple ranges from the optical chronographs is to fire enough rounds for a reliable average and then move them and repeat. It's a lot of work.)

I use a chronograph to choose field ammunition velocities. All bullets have an ideal impact velocity range. Get your bullet maker's data on this. Apply the minimum and maximum ranges you expect to shoot and the bullet's ballistic coefficient to a ballistics range table calculator. Find the muzzle velocity that ensures impact at your maximum range is still within the manufacturer's recommended minimum velocity and that it doesn't give you too much velocity at your closest expected range. Once the computer has given you that muzzle velocity, the chronograph lets you produce a load to match it.

Originally Posted by jmr40

If you look at a book load showing 60 gr of powder should yield 3000 fps with a 150 gr bullet as the max load, then 3000 fps is the important number, not the 60 gr of powder. Without a chronograph most people keep adding powder and comparing group sizes while looking for traditional pressure signs. The problem with that is that traditional pressure signs don't show up until you reach 70,000 PSI, well over where you should be.

Without a chronograph you might incorrectly conclude that your 60 gr load is perfectly safe since it is showing no pressure signs. You could be shooting 3150 fps with 60 grains and still not be showing pressure signs. But you're certainly over pressure.

By using a chronograph you can monitor muzzle velocity as you work up your load. When you start getting close to 3000 fps you are approaching a max load. You may find that some combo's of rifle, brass, primer, and bullet will reach 3000 fps with only 57-58 gr of powder. That is where you stop adding powder.

In other cases you may find that 60 gr of powder is only getting you 2900 fps with some rifles. Technically it would be safe to keep adding powder over the book max of 60 gr and it would be safe in THAT rifle. I strongly advise against this because those loads could end up in another rifle where they could be dangerous. You're just going to have to accept that 2900 fps is all that rifle is going to do with that powder and bullet.

"First contemplation of the problems of Interior Ballistics gives the impression that they should yield rather easily to relatively simple methods of analysis. Further study shows the subject to be of almost unbelievable complexity."

Homer Powley

One of two reasons many chronograph instructions say not to try to use the instrument to assess pressure is that interior ballistics are complicated enough that it is easy to get turned around. Everything in Jmr40's post sounded very reasonable, but, alas, it is turned around.

If you need more powder to achieve book velocity in a same-length barrel, you have lower peak pressure, not higher peak pressure. This is because the larger quantity of powder is making more total gas. That extra gas holds the pressure up higher past the peak value, raising muzzle pressure. This means a larger portion of the bullet's total acceleration occurred after the pressure peak was done than was the case for the book authors. Since the total acceleration to get to that matching velocity was the same, it follows that a smaller portion was done by the peak value, which means the peak pressure was lower, not higher.

If you need less powder than the book level to achieve the same velocity in the same length of a "fast" barrel, then, because the lower total gas quantity has lowered post-peak and muzzle pressure, more of the total acceleration had to occur during the pressure peak. That means your peak pressure, even with that lower charge, is already higher than book peak pressure and you should lower the charge and accept a lower velocity if you wish to avoid exceeding the book peak pressure. How to figure that out gets into the real complexities of the relationships, but it can be estimated.

There are, in fact several ways to estimate the differences. Probably the easiest way is to put the same load into QuickLOAD and adjust the burn rate of the powder until you have a matching velocity in the test barrel length. The pressure it gives won't exactly match the measured pressures from Hodgdon or Lyman or other sources of measured pressure data, but if you change the adjusted burn rate powder's charge weight in the program to match your actual required change, QuickLOAD's resulting peak pressure will change in very close proportion to the actual change in pressure your charge made. So you can multiply the book pressure by the ratio of the pressure changes in QuickLOAD to get a very close estimate of the actual pressure peak value you are getting. QuickLOAD then also lets you change barrel length so you can see what you should expect from your barrel based on the expansion ratio differences for your cartridge.

[Ben Dover]

Uncle Nick

THANK YOU for that post!!! It was factual and very informative.

This is the kind of information that is needed on a gun forum.

[std7mag]

That's our Unclenick!

I use a Chrony Beta Master.
After i've done my ladder tests.
Then after shooting a particular load, i true my data by shooting 600-800 yards.
Aside from the Labradar, chronos tend to be off some.
Note i do this regimine in cold (20°f) and hot (90+°f). This is done to get the correct velocities at different temps for my Strelok ballistics calculator.

Garbage in=garbage out.

[Bart B.]

One of two reasons many chronograph instructions say not to try to use the instrument to assess pressure is that interior ballistics are complicated enough that it is easy to get turned around.

Several Instructors devised a simple test to see how many people read then followed written instructions for doing something before actually doing those instructions. 3 out of 36 passed the test.

The ten written test items said to do things; say your last name, scratch your ear, move your billfold to another pocket and other ridiculous things.

At the top of the page under the heading and above the test items were the "Instructions." Instructions read "Read the test items for spelling errors. Circle any found then hand the test paper to the Instructor."

[reynolds357]

Originally Posted by Bart B.

First off my bat....... Smart people ask those questions.

No such thing as a correct velocity.

If you use a given load from some source, it'll probably be several fps different than source data claimed. 50 fps or a lot more is possible and common

I never used a chronograph developing loads. Just test group sizes.

Spend your money on good rifles, reloading tools and components as well as learning good marksmanship skills. Small velocity spreads are no guarantee that smallest groups will happen

Fully agree. My chronograph collects dust.

[Bart B.]

If your bullets leave at the right place on the muzzle axis up swing as it vibrates, slower ones will be at a higher angle above the LOS than faster ones.

This "positive compensation" effect has been observed for over a century.

[stagpanther]

If the matching velocity charge weight differs by more than two percent, I additionally model both in QuickLOAD to get matching velocities by changing the burn rate for the new lot, and then adjust to match barrel times rather than velocities, as that holds me closest to a sweet spot.

That's an example of what I meant as a cross-check between the labradar's data reads and Quickload's adjustable load parameters. I'm not nearly as expert as unclenick--but I've learned a heck of a lot nonetheless. I use them to also check factory ammo.

[Jim Watson]

I have used a chronograph to get velocity for sight dope.
I used two chronographs to get cast bullet BC for BPCR sight dope.
These days I mostly use a chronograph for pistol power factor.
That does not justify a Labradar to my mind, I am just not doing as much as I used to.