Best Way to use a Chronograph?

[Peter M. Eick]

Ok, I am stretching here, but I am pretty sure my wife took the hints and got me a Oehler 35P chronograph for Xmas. Now the big question, how should I use it and what is the best way to understand the results?

My concern here is that even though I am using "book" loads, when I compare my reloads with factory ammo, mine usually seems to be a bit "more" then factory. This is even though I do not normally load max loads (accept in 10mm), I usually go with the 95% of max rule. I particularly see this with 9mm and power pistol. With 115 grn FMJ's, I am loading 5.9 grns (Max is 6.7 from the web page) yet when I compare these loads to factory 9mm, mine seem pretty stout. The rest of the pressure indicators seem fine, but I am cautious.

So, to reiterate, once I have a chrono, what should I do, and how should I use it for reloading?????

[Jeeper]

I mainly use it for long range calculations for hunting. It is nice to know what your path will be at a distance. I also used it to to basic stuff like comparing loads. I would suggest that you test the chronograph at differnt sun conditions. It will most likely give slightly different readings. You can also use it to test loads at differnt times of the year. I used to use mine a lot a few years ago and now I rarely do. They are extrememly usefull.

I hope Santa is good to you.

[slickpuppy]

Since buying one a few months ago, I am using mine to test loads across the spectrum. I can't believe I didn't have one before.

Fortunately, my CED chronograph does not have the limitations of needing sunlight because I have the battery powered infrared screens. Good thing too, because at our range I am shooting under cover out to 10 feet in front of the bench!

I have started testing the impact of load variables on target impact, accuracy, and velocity with mine such as bullet weight variance, bullet diameter variance, seating depth, and charge variance. All I can say is that so far it is an eye opener!

What I do is decide what I am going to check and then fire a control string of 20 shots with known velocity and accuracy with the Ransom Rest. Then I will run my test string and compare the results with the known control string.

With my testing, a Ransom Rest for pistol is really handy because you will be shooting over the same area of the chronograph on every shot and you eliminate a lot of the human element.

[HankL]

Peter, The best thing that I can tell you is keep records and be very consistant in setting up your test bed.
You know that you are a safe reloader. Shoot your loads over your test bed for a while and see what they look like. When you have load A showing about the same results after several shooting sessions you can be confidant in your setup. Once you have achieved repeatability you are ready to go.
I like to shoot groups over the chrono at 100 yds on a paper target. If the velocity your are expecting, the accuracy you are wanting to reach and the standard deviation of the velocity of the shots fired is very low you get a big w**die You will make sure to write this information down in ten places, commit it to memory and store it on at least 2 hard drives.
The info that you gain and retain getting to loads like that will be valuable to you when working up new loads. Keep up with the data that you acquire as it will save you time and money when working up or selecting components.
HTH, Have fun, Be safe and most of all Merry Christmas!
Hank

[C.R.Sam]

Variables.
Your individual chamber and gun.
Temperature.
Componant brands and batches.
Altitude
Barometric pressure.

You will be using it to compare your loads in your guns.

Make up some formes for each run. Log all the above variables on each form.

Keepin records a must.

Sam

[Peter M. Eick]

I guess maybe I was looking for different information.

Say I chrono up my reloads and I find I am getting say 100 fps faster then factory. Is this a concern or what? What about if the SD is over say 50 fps on pistol load, good, bad or what?

I can definately see the point on the record keeping, I have a big spreadsheet listing many factors of my loads but I hope to be soon adding the velocity and SD to it.

Thanks again.

[Jeeper]

I have always been way more concerned about rifle ballistics than pistol. The more consistant the better but there is always a line. I have usually worried about accuracy first and then the factors like Deviation and other things. It is nice to know what your reloads are doing no matter what happens. I have pages in excell spreadsheets for most of my rifle calibers. I have tested so many bullet and powder combinations with the chronograph that it makes me sick. I also added onto my sheets a column for what the group size was so that you could see if there are trends with the velocity and bullet selection

[slickpuppy]

Peter,
You are in to doing pistol, so, get the wife to buy you a Ransom Rest as well. Why don't you give us some more info on what YOU are trying to do. It sounds like you are trying to duplicate factory loads above all else with respect to velocity and accuracy?

[Peter M. Eick]

Mostly I am just trying to be safe. I am not out to push the envelope, just to be accurate and safe.

[Bobshouse]

I read a post somewhere that talked about using a chrony to get the maximum efficiency from a load. It went something like if you increase you load a quarter of a grain you should see a relative increase in velocity. Once you have reached the "maximum efficiency" of a load you will not see any notable increase in velocity for the powder added, which means you are feeding directly to increased chamber pressures. If I can find that article I will get with you.

I do not personally care to shoot "efficient" or "experimental" loads at the higher end of the scale, but instead strive for consistancy. I use my chrony to verify velocity from published safe loads and to insure that I don't get to wide of a variance between loads using different powders.

I also use the chrony to shoot many different types of guns at the range. When people see you have a chrony they will always want to see the velocity of their rounds. I tell them they are welcome to try a round, but if they shoot the chrony, they buy the chrony. More often than not, they let me shoot their firearm over the chrony instead Of course I have to make several test fires to determine if their gun shoots to point of aim first...lol.

Bob

[Peter M. Eick]

I like your efficency comment, that makes sense.

Interestingly, I have never once seen a chronograph, I have loaned ammo and a gun to a friend to test, but I have never seen the item I am asking for. I expect like you suggested, when I get it set up, there will be a lot of other curious shooters wanting to try it out (with me driving/shooting) of course.

Thanks for the advice.

[slickpuppy]

http://www.thefiringline.com/forums/...mum+efficiency

It may be young Steve Smith, mover and shaker, man among men's post in the above thread.

[nwgunman]

Hi Peter: If you're getting 100fps more than the data shows I'd suspect that something is out of whack. Especially if you're getting 1200+fps with "...5.9gr of Power Pistol". Usually it's tough to match the velocity given in the load books. Have you checked your scale? When you say "pressure indicators look fine" do you mean case expansion at the web area? Hows the cartridge OAL? Did you also chrono the "factory" loads as a check against your handload chrono results? Nice Christmas present, by the way. Glad to hear that your wife is friendly towards your hobby!

[Peter M. Eick]

Nwgunman,

You hit the nail on the head as to why the chrono would be useful. I do not know how my loads are doing, I am just guessing.

As to my 9mm loads, yes case expansion on the head seems fine (in line with factory expansion), primers are holding tight and overall the loads seem fine. The scale is an RCBS digital and it gets checked with the supplied test weights before during and after every session.

I will definately go on a testing kick of factory and re-loads, to see what the chrono says, but my goal was to know the question to be answered before I acquired the test data.

Thanks for all of the advice.

[jtduncan]

Nice wife!

Use it outdoors on a cloudy day on a tripod and be careful not to shoot it.

Great for testing the consistentcy of different powders.

Great for selecting an accurate and consistent powder.

Great for working up hunting loads especially for guys like me that shoot 44 mag out of revolvers and carbines.

I have an older Chrony that I need to replace but if you want to shoot indoors, make sure to get the indoor flourescent light attachments or your readings will be off.

And now you can test Longshot in 357 sig for your page too!

[dntorbert]

the best way to use a chronograph is by not using is at a backstop try a search on chronographs and destruction for some funny but sad posts

[WESHOOT2]

First, understand the following information is FACTUAL, not unsupported opinion.

Second, 'common thinking' or 'coventional wisdom' is just that, and certainly not always correct.

Okay, parameters set here we go!

> Velocity consistency is mandatory when we're concerned with BULLET IMPACT ("terminal performance"), but not very important when ACCURACY is our goal.

> Low deviations may have NO impact on accuracy.

> Powders should behave in a consistent manner when RETESTED in specific combinations.

> A chronograph allows 'mapping'; the progression of the relationship betweenm powder charge and velocity increase.

Example = I want to develop a load that makes IPSC Major from my 38 Super.
I pick a bullet weight and configuration, then pore over my published data.
I decide that I like the Rainier 151g TCJ-RN, so I know I need 1095fps to get there.
I load X.0g of Blowemup because my data suggests this will give me 1050fps ("start low work up slow").
I chrono, and my exact result is 1040fps.
I add .2g of Blowemup and retest.
I get 1060fps.
I add another .2g and that gives me 1080fps.
Still needing at least 1095fps, I add another .2g, but when I test that it gives me 1160fps. Hmmm.....

Now I know something is up. Maybe Blowmeup is not the best powder choice, so I look for something else that data likes.

I've had loads that go WAY faster, like this example, and even odder, I've had loads that SLOW DOWN when more powder is added.
I use (in most cases) .2g as my "add", and I "map" the progression of the relationship.
Examples as given may suggest to me a different powder or component.

And remember, ALL handloading starts with a complete understanding of EXACTLY WHAT I WANT TO ACCOMPLISH. Do I want a hunting load? Need consistent IMPACT velocities, so deviations are important. Do I want accuracy? Deviations are not critical for this type load, as I'm only concerned with reliable functioning (alway FIRST) and making bullets enter the same hole on target. (The VEY conventional wisdom that low deviations equal accuracy is NOT SUPPORTED by actual testing; the two are independent).

A chrono can also tell you if something is WAY wacky, because any load should be in the ballpark of published data. If it's NOT, slow down and check your work.......
Can also show idiosyncracies of specific guns.

Your results may vary; I always wear safety glasses.

[Pigshooter]

Like others have mentioned, there should be a noticeable linear increase in velocity as you increase powder charge. Theoretically, when you start to see less velocity increase from the same powder increase, you are pushing the pressure maximum and need to back off the charge.

Unfortunately, this is a very fine line in short cases, and as was noted, you can see some very wierd things happening. All of them of course indicate you are crossing a threshold of some kind and need to back off. It works better in rifle cases.

[Peter M. Eick]

Thanks for the comments.

The 35P seems pretty easy to set up. I got out my old tri-pod and have the layout down pretty good.

I will go test out some 10mm rounds tomorrow and see how it works.

Thanks again.