Chrony f1 master

[leadchucker62]

Good day everyone:
I picked up a chrony f1 master to help with my load development.
are these accurate and reliable.
the reason I ask is that I was doing some load testing with my 17 hornet.
using lilgun powder with loads from 9.5 gr - 10gr in .1gr increments.
shooting 4 shot groups.
my average fps at 9.5 gr was 3346
My average fps at 9.6gr was 3642
Thats quite a jump in velocity for .1gr

Any input is greatly appreciated
Z

My most accurate load was 10gr with a speed of 3849fps with the lowest es of 43 fps.

[Bill K]

That does seem to be quite a bit of jump with only 1/10 of a grain. However in small case's, Lilgun will raise pressures very quickly, so you must use and proceed with it, with caution. Bill k

[moorepower]

It's not the Chrony.

[TinMan]

If you haven't used a chronography much before, you will learn a lot from its use. Consistent lighting conditions will matter a lot, overcast is usually better than bright sun and clouds. Make sure the direct sun doesn't hit the sensors.

You can also become a better reloader, seeing where little changes make a difference. Watching the variabililty of your loads. It is best to strive for loading technique that results in the smallest variability for a group. I usually use groups of at least 5 shots and measure the standard deviation, since that is a better statistical measure of variability than the extreme spread. it is also worthwhile to plot your chrony results, so you can picture the differences better. Plot the average velocity VS the powder charge weight to see if it is linear or bowing downward. The latter indicates pressures are getting near max.

I would repeat your load development loads to see if they repeat or if they are different. Hope this helps.

PS, My buddies and I have used three different models of Chronys and two different Pacts over the years, and they are pretty consistent performers between the brands and models.

[Chickenthief]

Were all cases prepped the same way?
Neck tension might account for the jump in speed (and pressure).
But it is @ 10% jump in speed and that is way to much for .1grain powder. Sure you didnt mix them with a higher load?

The Shooting Chrony varies only 1:200 or 0.5% so no more than @17fps at 3360fps is the fault of the chrony.

[trotterlg]

About the only difference in reading would be where on the bullet's shadow the sensor triggers, so the maximum error will likely be related to how long the bullet is related to the distance between the sensors. Probably a very small error. Larry

[georgeld]

A few things I learned about Chrony's. The reason they put the whole unit in front of the gun is so they can sell more of them.

Two more things BEFORE you take it out again. Replace those wires with 1/8" wood dowel rods, hit the wires and you stand a better chance of wrecking the thing than not.

And: cut a piece of Plexiglas 1/8" or 1/4" thick and set it in front of the screen. Powder granules can and will penetrate it and wreck it too.

And yes: .1gr increase WILL blow up a gun, be mighty careful with those small cases and which powders you use.

I provide this info as I've had these experience's myself and hope to save you from the same mistakes.

Good luck and enjoy learning more about reloading with this new toy.

[wally bennett]

Crony,s are very sensitive to sun and clouds to be certain that they dont cloud(pun) the readings make a light box and put incandesant builbs in one 40wat over each senser every reading will be taken in the same conditions DONT USE FLORESENT LIGHTS the flickerings give bad readings.
0.1gr of an increase in charge with that jump in vel shows the ligjting conditions are not constant OR YOU ARE NEAR THE MAX FOR THAT POWDER CHARGE!!!!!
Wally

[Roverhound]

With the .17 HH and Lil'Gun your loads reflect what I got also. Actually today I have 50 rounds loaded of my best using 20 gr and 25 gr bullets to check for consistency. 25 of each.

[Dean2]

In my experience I would say your Chrony is reading right. For inexpensive units they are actually amazingly accurate. I have tested them against much more expensive units and their error factor is on par with the much more costly units.

While they are a little sensitive to light, I never use the sky screens and the Chrony will read or not, depending on the light, but the light will NOT affect the accuracy of the speed readings. The suggestion to replace the wire rods is a good one, I use drinking straws marked 5 inches up with black electrical tape.

Accurate readings are affected by; 1 - muzzle blast from being too close can goof the accuracy, 2 - burnt powder residue, wads or collars/sabots going over the sensors can affect accuracy and 3 - shooting exactly square across the sensors.

Easy trick for lining them up square to your line of bullet travel is to put a laser in the muzzle of the rifle as it sits in the shooting rest and use the laser dot on your shirt, over the Chrony to align it.

The large speed difference you are seeing is the result of the very small case capacity in the 17 Hornet. I have seen this with all the powders I have tried including 1680, Lil'Gun and 2200.

Have fun with the new toy, they are the single most reliable pressure indicator the average guy has for testing reloads.