Chronograph

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.
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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."
 
Bart B. said:
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
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Fully agree. My chronograph collects dust.
 
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.
 
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.
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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.
 
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.
 
Labradar has it's quirks--but overall the time saved and tracking features easily pay for themselves quickly over less expensive optical chrono--I'd never even consider going back to an optical chrono (unless my labradar goes down and I have no other back-up).
 
That's pretty much where I am with it. I frequently lug a lot of stuff to the range so anything that saves setup time and automatically makes the records I would otherwise have to enter manually, is a plus to me. I've still got my opticals on standby, though.
 
Jim Watson said:
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.
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I dont use a chronograph for dope. Estimate velocity and plug in manual poi at several distances to tweak it.
 
Am still considering the use of a chronograph one of the most important safety measures available for loading higher pressure rounds. Is it as accurate/precise as more expensive methods, not likely. But if you are getting velocity's higher out side what you are expecting, you are forewarned. It gives a cheap method for checking the effects of differing powder lots, as learned from using RL-22 years ago. Also as a method for checking hand loading practices, as learned from not having enough case neck tension with pistol rounds.
 
The trick with pressure is you have to remember velocity and bullet mass will give you muzzle energy which gives you the average force behind the bullet in the bore. After dividing that force by the bullet cross-sectional area, you get average pressure. But because the peak pressure and the muzzle pressure aren't changed the same amount when a powder charge is changed, either by weight or by type of powder producing the velocity, you can't get to peak pressure directly from velocity. That takes using a program like QuickLOAD to mimic a test gun load, then altering it to mimic what you are getting for velocity, and then seeing what the resulting percent change in peak pressure was and applying that percent change to the measured test barrel pressure. What you can say, though, is that if you get less velocity from a load than the published load got, even after adjusting for barrel length, then you are running at lower pressure than the same charge got in the test gun.
 
Thanks to everyone for their input and very useful information. Have to be honest some of the posts, I have to read twice to fully understand it, but non the less very informative. I always start at the bottom and always load 5 groups of .5 grains. Haven't come close to max loads yet.

Definitely am not able to spend on a Labradar.
 
While not nearly as convenient, you should be able to get a chrono for close to $100.

As an example lets say you are using factory load information. Now suppose there is a factor in your particular rifle, caliber, powder /bullet/primer lot that would lead to higher pressures. Say the book says the combination gets about 2600 fps, but you chrono 2800 fps for the combination. The velocity you get is a heads up. Of course there are other numerous factors to consider like barrel length etc. Not saying it's accurate/precise measurement of pressure, but certainly an indication that is relatively cheap, and in some opinions more useful than reading primers/bolt lift etc.

Just an opinion.
 
Cheaper chrono's can have problems with low angle sunshine, and give bad readings on occasion. On the F1 owned, this is mitigated by 2 small cardboard pieces placed in slot directly in front of the "eyes". As far as being "exact", how would you determine the exact velocity to determine that? Uncle Nick would likely know. There are comparison vids to compare various chrono's, and i would likely trust the accuracy of Labradar's readings over a cheaper F1. Alot of how the F1 reads may be influenced by how it is set up each time, but how accurate do you actually need?

https://www.ar15.com/forums/Precisi...mparison-FYI-APP-NOW-AVAILABLE-in-OP/10-6511/
 
Thank you, almost seems like a hit or miss with a chronograph???
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As my brtoher told me when I got my first (big) motorly. there are thsoe who have laid tghem down and those who are going to (5 x over tghe years - forntualy none at signan speed)

Chronos are, those who are going to shoot them and those who are going to (not to mention someday they will fail). So get a decent one with the remote reader for $100, shoot one, have one fail and you are up to $300.

And the time spent fiddling getting it setup while pole look at you (I hate the look and I hate the ones who I am looking AT!)

Ergo, Lab Radar or Bust (get what works right or nothing)
 
RC20 said:
As my brtoher told me when I got my first (big) motorly. there are thsoe who have laid tghem down and those who are going to (5 x over tghe years - forntualy none at signan speed)

Chronos are, those who are going to shoot them and those who are going to (not to mention someday they will fail). So get a decent one with the remote reader for $100, shoot one, have one fail and you are up to $300.

And the time spent fiddling getting it setup while pole look at you (I hate the look and I hate the ones who I am looking AT!)

Ergo, Lab Radar or Bust (get what works right or nothing)
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I have lost count of how many chronographs I have seen shot. Its usually the bench rest guys who shoot them. Bubba always seems to never kill his chrono.
 
Have personally shot and killed one, while only winging another. Used to use one quite a bit, and goyt in troulble swithing guns while trying to shoot low over the sensors to beat the sun. Working up loads for over 30 calibers, used to use a chrono almost every range session. If was just starting out, anticiptating using it alot and had the resources, would be getting a labradar. Using a chrono can be real pia at crowded range.
 
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