Lies, Damn Lies, and Chrono results!

First topic message reminder :

I recently realised that when my local range is quiet (most afternoons I'm all alone) I can set up my Chrono at about 15 feet in front of my favourite bay and, if I set my targets just right, I can shoot a lot of my Slow Fire practise over the Chrono and record almost every shot. It looks like this from the firing line:-

Unfortunately the range is only 15 yards maximum, but it is less than 10 minutes away and perfect for practise with standard 50' targets. I normally put a set of "900" targets up, but am currently focused on SF practise each day with my 22 and then my SARO wad gun - on the advice of my mentor Roddy. So I put up 6 SF targets at a time and can easily Chrono the lower 3 targets.

Since I'm trying to work up a reliable "soft" short line 45 load, this is a very time efficient setup. The only disadvantage is that I have not been able to get the Chrono to "talk" to my phone and so I'm having to release my grip after each shot and write down the result.

However, I have very little experience with the basic Caldwell Chrono and I don't know whether my results are representative of actuality.
Yesterday I used the Chrono on two SF targets with 4.1 N310 loads, but they did not reliably eject. Then I repeated one target with factory Federal GMM ammo as a kind of benchmark. 
Today I tried upping the powder to 4.2 N310 and it was more reliable, I used the Chrono for three SF targets.

It is very noticeable that the Standard Deviation for the Factory Ammo is much less than my reloads (I've been very careful to repeatedly check the powder drops for these small batches of ammo - I'm not seeing any significant variation - using an XL650 with Dillon measure and small bar - Brazos Hi-Tec 160 LSWC bullets).
The first shot today felt quite normal, but the Chrono reported a much higher velocity (in yellow). I think that is a Chrono error and I have excluded it from the table.
All of yesterday's strings and the first four strings of six today were fired almost perfectly over the body of the Chrono, but I was lazy to go and make a very small adjustment to the Chrono position for the last two strings, so the bullet path would have been slightly higher and to the right of the Chrono body. It is noticeable that the velocity results are quite a bit lower.

So, my questions to the Chrono experts out there. Are these SD results typical, or is there a problem with my setup or my Chrono?

Ah. OK. Makes sense. Long time since I did any Math (and I hated it back then!).

Thanks.


.

As Swissyhawk determined, your SDs are consistent and reasonable acceptable. There isn’t a statistically valid differential between the three sets of results. The next question is how well does your pistol function with each load. If the 4.2 load functions fine, then I’d use that because it appears to be very slightly better in variance. If you shot a much larger sample (100 or so each load) you’d get more confidence level in saying that one load is better.

When I shoot at an indoor range I send the target out to 16.7 yards and shoot on a 50 foot target. Then the target distance is very close.

I’ve used my LabRadar indoors at 50’ a lot and also outdoors, mainly at 25 yards but have used it at 15 yards, also. It has not failed me at all in the two years that I have had it.

I don't own a RR or chrono, but wanted to offer an interesting example of why some of us like to check details to find if there is a problem.    

I've had some phantom issues since refreshing springs at the beginning of outdoor season, but never thought to question the manufacturer's spring rating.   It turns out the Ed Brown 19 pound hammer springs I bought are closer to 22 pounds when I tested them.  my fingers could even tell a difference compressing them vs the spring I took out.   

I agree, I have more control over improving my shots than perfecting the pistol's spring balance, but we are all wired differently and some of us want to learn/prove things ourselves and then contribute back to the collective knowledge.

BE Mike wrote:

1joel1 wrote:

BE Mike wrote:To be frank, you are wasting time working up an accurate load using a chronograph. Your time would be better spent testing for accuracy with a machine rest or sandbags and scope if you are good at it. Otherwise, spend the time working on fundamentals.

I disagree. You can gain a lot of useful information from chrono data. It all goes into the mixer and helps you with consistency.

Joel

Yes, it is amazing that I made outdoor master and distinguished pistol shot without ever using a chronograph! I did use a Ransom Rest and even had my own set of portable turning targets. I worked on the fundamentals and at a certain point, I also studied the psychology of the game. There are so many good tried and true recipes for good bullseye pistol loads that there is little need for experimentation. Shooting as many matches as practicable also was in my plan.

Well, no need to be snarky about it. I didn't say that it was necessary to use a chronograph to become a good shooter, but it does offer good information. You said it was a waste of time and that is what I disagreed with.

1joel1 wrote:

BE Mike wrote:

1joel1 wrote:

BE Mike wrote:To be frank, you are wasting time working up an accurate load using a chronograph. Your time would be better spent testing for accuracy with a machine rest or sandbags and scope if you are good at it. Otherwise, spend the time working on fundamentals.

I disagree. You can gain a lot of useful information from chrono data. It all goes into the mixer and helps you with consistency.

Joel

Yes, it is amazing that I made outdoor master and distinguished pistol shot without ever using a chronograph! I did use a Ransom Rest and even had my own set of portable turning targets. I worked on the fundamentals and at a certain point, I also studied the psychology of the game. There are so many good tried and true recipes for good bullseye pistol loads that there is little need for experimentation. Shooting as many matches as practicable also was in my plan.

Well, no need to be snarky about it. I didn't say that it was necessary to use a chronograph to become a good shooter, but it does offer good information. You said it was a waste of time and that is what I disagreed with.

If it adds to your confidence to see that your velocities are consistent, then you will shoot better regardless of the opinions of others.
Most shooting is done between the ear muffs and that's where most gains are earned. 

james r chapman wrote:Bet their gun builders did.
Random rest anyway.

+ 1

So, just to kind of wrap this up. I loaded another batch with 4.4gr of N310, all other settings the same. Weather was a bit colder, over-cast and windy. I set the SF targets a bit lower on the stand so that they were in perfect position above the Chrono and moved it across slightly for each target to try to get as consistent readings as possible. The Chrono did read every shot this time, so I think I've got the positioning just about right now.

The overall SD is across the entire 30 results to be more mathematically correct. The velocity was slightly lower than I expected (maybe due to colder conditions?), but the entire batch of 60 I shot felt consistent and smooth. I did have one FTE, but that was down to me forgetting to put a drop of oil on barrel and slide as instructed. After that no problem and the brass was jumping nicely into the net.
Most importantly, I was able to produce decent groups. These are normal offhand. First the Slow Fire - not at my best that day - the two fliers were down to me, but a nice group of 8. On a 50' SF target

And the best of the Timed Fire cards. On a 50' T&R target.

I am now satisfied with these results.
It has been a learning experience using the Chrono and it has helped me to gain more confidence in my reloading skill and recipe development.

Thanks to everyone for their comments and advice.

That’s some good info!  I love the 160s but my gun gives me and another shooter I shoot with headaches.  I’ve been using BE and get the more than occasional failure to eject.  I wanted to try N310 but was told by a well known smith to not use N310 with lead.  Seems you’re having no issues.  Think I’m gonna try it.

Thanks for the data