Is a Chronograph Necessary?

[noylj]

Isn't it something that this toy has become a necessity for jobs done quite well for decades without it?
As I pointed out, pressure/velocity is NOT same for different guns, so a chrono can not be used as a reliable pressure indicator, unless you have "calibrated" with the gun in question.
The main answer is the same: a chrono is FAR from a necessity and is simply a toy for most. Fun to know, but not required--except specifically for power factor and external ballistics at long range.

 

[Andrew Leigh]

There are very few things in life that are "necessities" to argue that point is rather mute. Most of what we acquire in life is to make our lives more convenient and comfortable and so it is with a chronograph. It gets you to a reloading result quicker, cheaper and safer than without one.

 

[Reloadron]

I believe if we go back over the past few years we will see that in every thread along these lines involving a chronograph there is the same consensus. The chronograph is a tool and simply a nice to have tool but not an absolute necessity.

One very nice thing is that maybe 20 years ago or more a chronograph was a pretty expensive tool but with advances in the technology curve a chronograph, much like a digital scale is much more affordable. Not only more affordable but with a greater number of features available.

Ron

 

[carbine85]

They aren't necessary but nice to have. When working up loads it's nice to see how your rounds compare to other loads, published data and consistency.
I had problems with a load once. When I chronographed the loads I found out that .2 grains difference in the powder changed the velocity by 150 FPS. After I hand charged the powder I got it down to 25 FPS. I ultimately decided that the powder wasn't good for my purpose.

 

[kcofohio]

I like this thread. I have often convinced myself by something I read or hear, that I need a chrono.

It seems every time I have a $100 or so, I find something else in either reloading or gun parts to spend it on.

I reload for plinking that won't beat up our guns. And use published data. Now if it came down to having to use this 8# jug of International. That would need a chrono.

 

[RentaCop]

OK, I'll come out and admit that I am an unmitigated newbie. I've read all kinds of reloading books and watched YouTube videos produced by people who seem to know what they are doing. Muzzle velocity seems to be the pivot point of reloading. Do I need a chronometer, or can I just use a middle-of-the chart powder charge suggested by one of the reloading books for the caliber, bullet type, and powder that I have - and call it good enough?

Thanks!

No, but they are a handy gadgit to have and only supply more valuable data. Same can be said of Quickload, handy, but not required. I use all three; Books, QL, and a chrony, but that's my chioce.

Just 'cause a book and/or program says you'll get XXXX (ft/sec), with XX bullet, with XX grains of a certain powder, at XX seating depth, doesnt mean squat. You'll never know until you put it over a chrony.

Sometimes "middle of the chart powder charge" is not middle of the chart.
http://www.thehighroad.org/showthread.php?p=9479870#post9479870

 

[Hondo 60]

I have one & use it especially when working up new loads.

Once there is no (or minimal) unburned powder & accuracy is acceptible, it's nice to know how fast the bullet is going.

Or on the low end, am I close to getting a bullet stuck in the barrel????

Or when trying to recreate factory loads.
how fast is the factory load? how fast are mine??

SO is it necessary??????? No, but at least to me it's comforting.

 

[noylj]

>Once there is no (or minimal) unburned powder & accuracy is acceptible, it's nice to know how fast the bullet is going.

Sorry, but unburned powder is not an issue and accuracy is everything and a chrono does not tell you accuracy.

>Or on the low end, am I close to getting a bullet stuck in the barrel????
Somewhere south of 400fps. Of course, if the bullet leaves the barrel, it didn't get stuck, so the chrono told you nothing the target doesn't

>Or when trying to recreate factory loads.
how fast is the factory load? how fast are mine??

Why? Again, this is of some help for hunting/long range shooting for exterior ballistics, but not of any importance for most shooting. It doesn't matter if my .45 Auto is shooting at 800fps or 900fps. It is hitting the target that counts and either will work for any real world purpose the gun can handle.

Again, fun tool to have and nice to know, but not necessary and of little real help--except, as I said for power factory and external ballistics.
My only thing is that the tool seems to become more important than the shooting and target. Suddenly people are telling new reloaders that they NEED a chrono.
I used chronos back when you used two sheets of paper with a circuit imprinted and when the bullet broke the first circuit the timer started and when the second circuit broke the timer stopped. Then you calculate the speed by HAND based on the distance between the "sensors" and the time. Did a lot of work with it, but it was still just a toy.

 

[Potatohead]

I think everyone should experience the joy of shooting a chrony!

 

[Andrew Leigh]

I think everyone should experience the joy of shooting a chrony!

Then you bought a target and not a chrony ....... bad luck, sorry to hear that.

 

[cfullgraf]

See, chronographs are not toys, they are targets!

I have had two expire from lead poisoning. Proves the adage "that haste makes waste".

 

[Potatohead]

Then you bought a target and not a chrony ....... bad luck, sorry to hear that.

Ive actually not shot mine YET-because Ive yet to take it out of the box. Im trying to let it enjoy its life for a little while longer because I have a bad, bad, feeling that I might be the type fella that shoots his on the first day out.

 

[cfullgraf]

...I have a bad, bad, feeling that I might be the type fella that shoots his on the first day out.

Just take your time and remember the offset between the bore and your sights.

 

[Potatohead]

Yea, Im a bit concerned about that. And by remember, You mean...? Aim a little higher than you think you should?

Im going up to Tn to shoot on a buddy's land here at about 2:30...thinking hard about taking the chrony out for it's first test drive.

 

[Walkalong]

You mean...? Aim a little higher than you think you should?

Yes, If your scope is 1 1/2" above your bore, make sure the scope hairs are at least 1 1/2" above the body of the chrono. ARs can be more than this.

Note how far up my aiming point is.

Also, don't get careless with a pistol and be this guy. I am not going to call any names, but I know the fellow real well.

 

[cfullgraf]

For an AR, the scope centerline and bore centerline is 2-1/2".

Aim high, the light shields are less expensive than the electronics.

For some of the chronographs, the metal rods that support the light shields can be replaced with wood dowels. Cheap and easy to replace if they get nicked by a bullet.

 

[Squeaky Wheel]

Silly question: how do you figure out pressure from knowing the velocity? I assume that there are equations for calculating it based on bullet weight and other factors, but for those of you who do this, what do you use? Do you use software to do it, a website, calculate it yourself?

 

[Potatohead]

I believe you have to have specific equipment.

 

[mljdeckard]

I'm with RC. As long as it's accurate, I'm not very concerned with velocity.

 

[Potatohead]

Yes, If your scope is 1 1/2" above your bore, make sure the scope hairs are at least 1 1/2" above the body of the chrono. ARs can be more than this.

Note how far up my aiming point is.

Also, don't get careless with a pistol and be this guy. I am not going to call any names, but I know the fellow real well.

LOL..

thanks for the help fellas. Im T-2 hrs and counting, from dragging mine out for the first time I think.

My scope is super high, it sits on the carry handle since I ignored my fathers advice about taking my LEO uncle with me to purchase my first gun/AR. I just had to rush out and buy it without doing any research on them first, or taking any help with me. Because I know best, and why would you need any help buying an AR, you just load it and shoot it, right?:banghead:

Pretty sure I see a tiny bit of a smile crease my dad's face when I tell that story.

Possible we wont even make it to the chrony, I got 2 cases of grapefruit from the office. Gonna spread em all out at the 75yd line and make some grapefruit juice!

 

[SDGlock23]

I say no they aren't necessary, but after having one I could never just not have one. They tell you a lot about your reloads, they're just good for getting to know your handloads better, not just how they group.

 

[Reloadron]

Silly question: how do you figure out pressure from knowing the velocity? I assume that there are equations for calculating it based on bullet weight and other factors, but for those of you who do this, what do you use? Do you use software to do it, a website, calculate it yourself?

I don't believe you can. There is much more to a chamber pressure curve than just the velocity of the bullet exiting the barrel. Chamber pressure or more so the accurate measure of chamber pressure is a science unto itself. While a good accurate chronograph will give you velocity there is no easy mathematical bridge to get you to chamber pressure knowing velocity.

Just My Take
Ron

 

[Walkalong]

I agree, you can't. The velocity alone does not tell you pressure. X velocity with powder A can have a different pressure than X velocity with powder B.

When the chrono can be handy is when you get surprising velocities. As in, whoops, I did something wrong. There is no free lunch, so if you are getting 200 more FPS than the book tells you you should, it should set off an alarm with you.

 

[Andrew Leigh]

Reloadron,

A Chrony along with decent internal ballistic software like QuickLOAD will get you very, very close to the actual pressures.

 

[Reloadron]

Reloadron,

A Chrony along with decent internal ballistic software like QuickLOAD will get you very, very close to the actual pressures.

Yes, I have read a little about QuickLoad but haven't used it. However, my read is that Quickload is using more entered data than just a velocity read from a chronograph. My read on Quickload is you input the data:

The following is the minimum input needed to calculate load data using QuickLOAD:

1. Select your cartridge from the drop-down list. If your cartridge is not listed see Search cartridges of same caliber below.

2. Select your bullet from the drop-down list. If your bullet is not listed see Search bullets of same diameter below. I selected a .308 caliber 220 grain Sierra MatchKing bullet.

3. Enter the cartridge overall length (COL) you actually use. This is an important value because it determines the bullet seating depth and case capacity taken up by the bullet. This change in case capacity greatly affects pressure and velocity. This value must be updated when you select a new bullet.

4. Enter your gun's barrel length.

5. Select your powder from the drop-down list.

6. Enter the amount of powder in grains.

7. Click Apply&Calc to see QuickLOAD's calculated output.

It's a good idea to measure the Maximum Case Capacity, overflow and input this value to make QuickLOAD's calculations more reliable for the brass type you use.

The software will use the entered data and output the following:

1. Muzzle Velocity in feet-per-second and meters-per-second.

2. Projectile Energy at the muzzle in ft.-lbs. and Joules.

3. Maximum Chamber Pressure in pounds-per-square-inch and bar. The background of this output box will change color as you approach #4 Pmax.

4. Compare Maximum Chamber Pressure to Pmax, the maximum allowable pressure for the selected cartridge.

Notice the predicted muzzle velocity is 1238fps and 1050 is the usual target for subsonic loads. QuickLOAD over estimates muzzle velocity by 150 to 250fps for most subsonic loads. Using this load of 11.1 grains of AA1680 I get around 1020fps from the chronometer. Supersonic loads are much more accurately predicted by QuickLOAD.

Again, since I don't use it I can't really say how accurate the results are and I have nothing for comparison.

So back to is there a way to simply convert velocity as read on a chronograph to chamber pressure of the shot? None that I know of.

Ron