Number of rounds through a Chronograph?

[ms6852]

I was wondering if there is a standard or an average amount of rounds you fire through a chronograph, to determine the velocity with a specified load. For example do you shoot 3 rounds,5, or 10 rounds than get the average?

I am trying to determine how many rounds of different loads I should reload to perform a ladder test. I know that the rounds are loaded incrementally from a starting point to determine which load is most accurate for your rifle. But once I find the load for my rifle would shooting 3 rounds of that load be enough to determine the average velocity or should I go higher?

 

[rcmodel]

Personally?

I would go 5.

Then if a reading is goofy on one of the 5?
You still got 4 to average.

Which is 2x better then the average of 2 if you only shoot 3, and 1 is goofy.

rc

 

[toiville2feathers]

I shoot 5, and thats because I shoot 5 for load development. It gives me a better look at the deviation thats occurring and that translates into the grouping of the load.
tight group, velocity deviation is low

 

[plmitch]

4 or 5 at the most.

 

[blarby]

Through ?

The average is about one per user, if the forum comments are true.

Personally I'm at Zero, which i'm stoked about !

It doesn't read velocity very well, but it does gauge light AP ability fairly well.

Over-

I do strings of ten.

 

[tightgroup tiger]

I knew that was coming.

I thought the same thing from reading the title.

 

[steve4102]

But once I find the load for my rifle would shooting 3 rounds of that load be enough to determine the average velocity or should I go higher?

Shoot em over the chrony while doing your ladder test load work up.

 

[cfullgraf]

Statistically, the larger the sample size, the better the sample represents the entire population.

But, as most have already said, I also usually shoot 5.

On occasions, I will shoot up to 10 if I am looking to get a bit better information.

 

[ColtPythonElite]

I shoot ten, drop the highest and lowest, then average the rest.

 

[Don McDowell]

10 shots is the number I'm looking for when I want a true average, and to see what the real spreads are.
And have to agree with Blarby, over is much better than thru.

 

[jwrowland77]

When I'm trying to find my stats for my rifle rounds, I normally shoot 25 over my chronograph. It looks like I shoot way more than most. LOL. I normally do it while I'm practicing so I'm not really worried about the chronograph. I have the MagnetoSpeed. Easy to attach and remove.

 

[Walkalong]

I shoot 5, 6 or 7 usually. It is a small sample and statistically inaccurate, but close enough to give me an idea of what I have. It is just one small piece of the puzzle. I do run samples of possible good loads again, and I run them in hot weather and cold weather.

 

[GaryL]

I agree with Walkalong.

A statistically accurate sample size would require 3 shooters firing 20-30 rnds each. And that would only be accurate for the weather conditions encountered on that day of testing.

Like many others, I shoot 5 of each, since that's the sample size I use to see if it's a decent load.

 

[ms6852]

Thanks guys for the input and those of you that are picky about semantics,(over, vs. through) I used the term through because of this.

http://www.midwayusa.com/product/531741/shooting-chrony-f1-chronograph

 

[Rule3]

I normally shoot 10. It is also helpful to use the same headstamp and number of fired brass. Each powder charge should be weighed, try to eliminate as many variables as you can.

Having different shooters shoot the same round? That has nothing to due with statistical validity of velocity?
The human factor does not change the load. Accuracy yes. A true test would lock the firearm in a ransom rest of test chamber and as mentioned extreme temp changes if you live in an area that has them.

The more rounds the better the sample

 

[ms6852]

Never thought of the same headstamp on the brass, thanks for the headsup Rule3.

 

[cfullgraf]

Thanks guys for the input and those of you that are picky about semantics,(over, vs. through) I used the term through because of this.

http://www.midwayusa.com/product/531741/shooting-chrony-f1-chronograph

Imagine the Chrony without the diffusers over top of the optical sensors. Then you are shooting over the chronograph.

There are times that you may not use the diffusers.

Chronographs do not react well when shot through with 45 ACP or 204 Ruger. They will definitely turn the chronograph's lights out.

 

[FROGO207]

As stated one shot and it is all talked over.:banghead: As to how many in a string I like 10, (easier math) but when verifying a new batch of propellant I usually only shoot 3 - 5. Now if I get erratic results with a load I will go as high as 20 on occasion.

 

[Vol46]

5 or 6 when I am working up a load, but that is because I begin with small batches at each increment. Gives a rough idea, but probably not a really accurate result as others have said. Once I have a load with pretty good performance, I will test 10 or 20 to get a velocity, spread, & SD that I can be more confident about.

 

[CountryUgly]

5 or 6 when I am working up a load, but that is because I begin with small batches at each increment. Gives a rough idea, but probably not a really accurate result as others have said. Once I have a load with pretty good performance, I will test 10 or 20 to get a velocity, spread, & SD that I can be more confident about.

What he said ^^^^ must be a southern thing???

 

[Nordeste]

All I've run through my ProChrono Digital have been my 9 mm reloads, and whenever I had a new load to test, I always run 5 cartridges, sometimes 10. Enough to give me an idea on whether I'd make power factor with that load... or not.

Once I had the proper load in mind, I loaded larger batches, and whenever I felt like it I run another 5 or 10 through the Chrono, with very similar results.

 

[Crashbox]

I prefer a minimum of ten shots; I've ran as many as 25 of each loading though (pistol). One reason I was taking such a significant sample is I wanted to see if there was a substantial improvement in the standard deviation of weighed charges versus thrown ones, which there was. At such short normal shooting distances for pistol, however, it doesn't seem to matter with me accuracy-wise, YMMV.

 

[stavman11]

I usualy do 2 groups of 5.... I am also Usualy testing accuracy as well as FPS..

So it works well for me

 

[me26245]

I shoot10 round groups for accuracy and velocity testing.

 

[witchhunter]

One shot will give the best average ES and you will think your load is better! Order some extra rods when you buy your chrono like I did. The rods will get hit, you cant see em very well through a high power scope. Aim high!