Trust the Chrono?

[Spiffy]

I have a glock 35 40 cal with KKM barrel. I shoot Falcon/Cast lead bullets. I have a ProChrono Digital chronograph bought new from Shooters Connection.

 

 

Now the questions.  I have started using e3 powder because of all the good reviews and information on BEnos.com about it. 1 of the 2 main guys with lots of experience with e3 is helping me with starting points. He says he gets 130 PF with 180 grain with 3.0 grains of powder @ 1.130 and it feels like your shooting clays. I shoot 2.8 grains of clays for my minor load but I get 144 PF.  When I load 180 grain with 3.0 grains of e3 I get a PF of 166 and it feels like the major loads I was playing with using N320. 

 

I am  pretty much the only one getting these level of readings. Everyone else gets the same general area as the 2 main guys.  As far as I can tell my scale is good to go. It reads within .1 grains of what the Lee Auto Disk online tool says each cavity is supposed to throw. 

 

So should I trust my chrono since it feels like a major load when I shoot?

 

 

 

 

 

 

 

 

 

 

 

Added: We are going to shoot 3 different chronos this weekend to see if mine is reading the same as theirs, or close to it.

[173rdABN]

Not sure about pistol barrels but sometimes rifle barrels can be noticeably hotter than others. Last Saturday we had this issue with a savage bolt gun and couldn't figure out why it was 150fps hotter than everyone else's guns.

If it's the same for pistol barrels, maybe you just got a abnormally fast barrel?

[Spiffy]

There are fast barrels and KKM is 'the' barrel for lead. There's no pressure signs so Im not worried about blowing my gun up or anything. It is kinda a wildcat deal where there is no published data but calls says use red dot info. And people have gone from there.  I'll experiment more and see what happens.

[R_Bert]

The ProChrono is pretty reliable, but make sure you are set back enough to minimize blast effects.  I am generally 15-20' or more from mine

[leroy]

Spiffy... Shoot 5 shots, throw out the high and low; then average the remaining 3 and see what ya get...

 

leroy

[Clod Stomper]

The ProChrono is pretty reliable, but make sure you are set back enough to minimize blast effects.  I am generally 15-20' or more from mine

 

This for sure.  I was testing .38 Spl. loads once and got a couple readings of 3000+ fps.  Had to move back a few feet.  

[StPatrick]

Spiffy... Shoot 5 shots, throw out the high and low; then average the remaining 3 and see what ya get...

 

leroy

 

While this is certainly a practical thumb in the wind way to go about things, the analytical side of my brain just recoiled sharply while hissing something about "social sciences math".

[Guest Lester Weevils]

While this is certainly a practical thumb in the wind way to go about things, the analytical side of my brain just recoiled sharply while hissing something about "social sciences math".

 

The high velocity outlier should be taxed to subsidize the low velocity outlier. Its only fair.

[StPatrick]

The high velocity outlier should be taxed to subsidize the low velocity outlier. Its only fair.

 

Ha!  Actually, my reaction was from years of practical factory experience and enjoyment of data crunching - outliers and flyers often contain far more information than the results you expect.  Identify and fix their causes and you get better results quickly and cheaply.  In this case, identifying why the slowest and fastest rounds are what they are carries no value in solving the primary problem, since the OP is trying to fix a chrony issue, but even knowing that couldn't prevent a mental flinch on my part.

[Dolomite_supafly]

I would make sure you are back some. I was shooting my 1911 and was getting very high numbers. I kept decreasing the charge but never seen an decrease of the velocity. I backed the chronograph off by 10 feet and the numbers settled down. When I say high numbers I mean 2,000+ fps out of a 1911 shooting 200 grain bullets. What was likely happening is unbirnt powder or the wave of gas was beating the bullets to the chronograph. The gas wave can set the sensors off if the conditions are right.

 

I have also had 223 loads that had a velocity of under 600 fps. The particles were beating the bullet then slowing down before crossing the screens.

 

And one more thing. Some chronographs can give sketchy numbers under clear blue skys. I would tape a piece of paper between the sky screens and sometimes I would even enclose the screens in paper. One more thing that can affect it to is floresent or LED lighting. They flash and that can affect how the sensors read velocity.

[Spiffy]

I moved back another 3 feet (1 more big step) and got more reasonable reading. I'm within .2 or .3 grains of what others get but I'm shooting lead.  The graphite coating on the hopper is helping too with a more constant charge.

[Dolomite_supafly]

Make sure you have a powder baffle in your powder measure. That single piece of equipment settled my charges down. I am getting SD numbers that are single digit and I "blame" that on the baffle.
 
Here is a great resource for making your own:
http://www.allmantrading.com/reloading/baffle.pdf

I use old license plates to make them. They are easily cut with a pair of heavy duty scissors. Edited January 15, 2014 by Dolomite_supafly

[Jamie Jackson]

So, if I'm understanding this correctly (please excuse my ignorance), the baffle prevents the powder from becoming more densely packed therefore allowing a more uniformed throw?

 

I'm hoping to pick up a chrono within the next few months (as finances allow). So I'm taking notes on this. Great info folks. :up:

[frankmako]

on my old 1985 chronograph it has a set back distance that you have to follow for pistol and rifle.  every time i use it out comes the tape to set the distance.  

[Dolomite_supafly]

So, if I'm understanding this correctly (please excuse my ignorance), the baffle prevents the powder from becoming more densely packed therefore allowing a more uniformed throw?

 

I'm hoping to pick up a chrono within the next few months (as finances allow). So I'm taking notes on this. Great info folks. :up:

Yeah, it keeps the same amount of powder weight at the bottom regardless whether the hopper is full or nearly empty.

[leroy]

Dolomite and Frank are exactly right RE: the setback distance... I generally use 10 feet as the distance for a pistol... The chrony will measure the speed of the powder particles... It evidently cant tell the size of particles, only the speed....

 

leroy

[Spiffy]

I got a lee auto disk so anything that helps the powder is a good thing. Since I'm just shooting minor for right now it needs all the help it can get.