Caldwell Chrony

This one.......

https://www.caldwellshooting.com/ra...tic-precision-chronograph/720001.html#start=1

Are these reliably accurate?

Shot a load ladder through mine today and got uneven results. Both as to ups and downs and as compared to some published load data.

Trying to decide who to trust.

Also, about how many shots can one expect to get on a new battery?

Good question. I have not been using it for the same loads to look for variation.

Been loading Satterlee load ladders.....increasing loads in increments of 0.2 or 0.3 grains and looking for nodes of same or similar velocities.

But while the velocities tend to go in the right direction (from low to high), they bounce up and down a lot getting there. Powder charges trickled up to be dead on for the desired charge. Within a grain or two of of powder of being where it should be.

Load being developed is for 270 win. Powder is from 56 to 60 grains of h4831sc under 130 gr Hornady Interlock. Hornady manual has velecity of approx 2800 fps from 56 grains. I got 2915 and it went up from there. This from a Rem 700......which I think has 22 inch barrel.

Distance to chrony about 12 to 15 feet. Started out with clouds that were starting to break up, but still no direct sunlight while shooting.

Looked at every primer, but didn't see any outward signs of pressure....at least to my untrained eye. All was still going well till I got to shot 12 of 16....and 59.3 grains, which is when the battery gave out and test ended.

But otherwise, test looked encouraging. With this Satterlee load ladder method, goal is to find a plateau of 2 or 3 shots where powder charge goes up, but velocity remains the same. I found a 3 shot plateau and as luck would have it, all 3 corresponding shots were touching.....very nearly the same hole. If that charge area pans out, I'll be all grins and giggles. It was right around 58 grains, which ls the Max load in Lyman 50th, but well short of the 60 grains that is a historical pet load for that powder.

But will now be curious to load up 10 rounds exactly the same and see not only where they print, but what the chrony has to say about all those. Still trying to decide who to trust.

BTW, on mention of Nosler load data, I have adopted the habit of trying to find at least 3 different sources of load data for anything I load. In this case, Lyman 50th, Lee Reloading Manual and Hornady reloading book. My preference is load data from whoever it was that made the bullet and who made the powder. Consider all of them and then start at reasonable looking bottom and work my way up. Found it somewhere between scary and amusing that 55 grains was at the midpoint of Lyman's range.....which started at 52 grains and topped out at 58. Hodgdon and some other started at 56 and went up to 60. Hornady went all the way up to 62 grains before calling it quits.

Here is an example of what I was seeing.........load was increased 0.3 grains each shot.

2903
+11
2914
+45
2959
+8
2967
-1
2966
-16
2950
+26
2976

If that kind of behavior is normal, then so be it. If not, then either I have a process (sunlight, muzzle blast, alignment, etc) type issue to sort out. That is assuming the chrony is reliable if I do.

Probably a good starting point is to take a reliable given....like a spring powered air gun.....and see how it does with that.

Yes......my intro to chrony. What remains a mystery to me is if the results of any chronograph reveal actual variations in velocity (are that accurate) or the variations come from ability of chrony to accurately clock the speed of a bullet. Again, trying to decide who to trust.

As for my predicament, for now, testing these loads is taking place at a public run range, which is only open from noon to 6pm, 5 days a week. Timing that to an overcast day is a limiting factor, as is sharing the range with others. During these tests, there were at least half a dozen others shooting on the 100 yard range, and to fiddle with the chrony requires calling for a halt while you mess around with it. Best time is while someone is downrange setting up targets. But even under best of conditions, where one is forced to setup is in the open, so if sun is out, sun is out. Wondering now if anyone has looked into placing a sheet or some type of opaque canopy over the sun screens? Better solution may be to move tests to a private location where none of that matters.

As for the Satterlee method, it is predicated on single (but accurate) measure of velocity from a single round......fired from a group of rounds where powder charge is increased in small amounts. Chrony most often mentioned with this method is the Magnetospeed, which clamps to the barrel and measures velocity at the muzzle. Because clamping something to the barrel screws up harmonics, and thus accuracy, there is no need to shoot targets. Could probably do it in your basement if you could do it safely.

But with the Caldwell, becoming obvious I need to work on setup and shooting process, and if such variation continues, will need to expand shot strings per load. What the method is trying to uncover is a series of incrementally increased powder charges that give you about the same velocity, which is an indication of an accuracy node. What I have discovered is that if you shoot those in such a way to ID the hole made by each shot (vs shooting as a group with no clue which shot is which), the accuracy node also shows up on paper. The three shot string that was ID'd by the chrony also showed up on paper, with the same three corresponding shots nearly hitting the same hole. Not sure if that was discovery of the accuracy node or coincidence. Only way to find out is to load a large set to same charge and see what happens.

BTW, one of the advantages of the Satterlee method (if it works) is you get to a reasonably accurate load with about 20 shots or less vs. 2 or 3 times that many shooting 4 and 5 shot ladders. A good thing when working with scare components as I am doing now.