Chronograph Results


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kinser11
January 8, 2009, 05:59 PM
Today, I set up the chrono and tested some of my reloads. To say the very least, I think the velocity variations suck! The weather was about 50% overcast so I decided to use the hoods along with the wires on the F1 Chrony. For those of you that have chrono-ed your reloads, how much velocity variation have you recorded? Have you compared your reloads to factory loads? I have checked powder amounts with consistency on both digital and balance scales. Seating depth remains within +,- .oo5. They are all crimped in the final stage. A variation of 50 -75 fps is not what I would like to see. The load was 4.8 gr of Titegroup with a 115 gr FMJHP in a 9mm Sig. Any and all experts may chime in. Thanks:)

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feets
January 8, 2009, 06:17 PM
What kind of variation were you getting?

The Bushmaster
January 8, 2009, 06:23 PM
Kinser11...Are we talking about ES (Extreme Spread)? Or SD (Standard Deviation)? Or AD (Average Deviation)?

If you are eluding to ES. It can vary as much as 0 fps (Probably almost impossible) to as high as the slowest bullet to the fastest bullet. In my case as low as 12 fps for 5 round to as high as 179 fps for 5 rounds. (I have all this recorded in a ledger).

I figure if I can keep ES within 50 to 60 fps difference for handgun rounds I good...And 20 fps for rifle...

kinser11
January 8, 2009, 06:27 PM
I'm looking at a extreme spread of 50 -75 fps. What is normal with factory ammo?

NCsmitty
January 8, 2009, 06:27 PM
Before you change anything, try the Chrony on a sunny day and see if you still get the variations.
How does it group?

NCsmitty

kinser11
January 8, 2009, 06:33 PM
I will try that after the next snow storm passes by!

Steve C
January 9, 2009, 02:38 AM
Here are some 9mm factory loads I've chrono'd and their associated statistics. For some reason when I was moving the data around the Wolf ammo STDev recalculated wrong, it should be 19.74 fps. Winchester +p+ 127gr SXT had the lowest variation but the 145gr Russian Barnual ammo was so close as to make no difference. You can draw your own conclusions from the data.

http://members.cox.net/scollins15/Pictures/9mBALLISTIC.jpg

Ridgerunner665
January 9, 2009, 02:53 AM
NCsmitty,
Why do you say that?

The diffusers (hoods) are supposed to be used on sunny days...you're more likely to get "misinformed" by your chrono on sunny days, diffusers or not...chrono's work best on overcast days.

USSR
January 9, 2009, 08:06 AM
...you're more likely to get "misinformed" by your chrono on sunny days...

+1.

Don

kinser11
January 9, 2009, 08:16 AM
Thanks for the data, Steve C.. It is apparent that I have more work to do to achieve more consistent results. It will be interesting to take measurements on a sunny day versus cloudy day with and without hoods. I was using a F1 Chrony. I don't know how they compare with other brands. If the bank account didn't look so flat, I would try a different brand of chronograph for comparison.

Galil5.56
January 9, 2009, 09:05 AM
I was using a F1 Chrony. I don't know how they compare with other brands. If the bank account didn't look so flat, I would try a different brand of chronograph for comparison.

I got an F1 about 16 years ago and it worked well until I "upgraded" to a Master F1 w/ remote... Best day was when it experienced a terminal ballistic event, and was replaced with a ProChrono Digital. The Chrony had to have bullets pass 3" or less above the sensors to read, absolute perfect alignment was a must or it was an error, and it was absolutely psychotic with regard to light. It did not matter with screens, no screens, xtra huge homemade screens, bright light, cloudy, sun angle...

The ProChrono just works, has a huge shooting area, and is nearly error/missed shot free. When I could get readings, the Chrony seemed accurate enough, but using it was an absolute chore, and got sick of wasting ammo and time. Maybe you are not experiencing what I mention; if so do yourself a favor and use something else and actually enjoy checking velocities.

Jim Watson
January 9, 2009, 10:35 AM
Most of my 9mm junk ammo has extreme spreads in the 20 to 50 fps range for 5 shots.
For a 115 gr Remington 9mm JHP and 4.7 gr Titegroup, I got 1215 fps, sd 13, es 35.

A PhD of my acquaintance studied the statistics on his factory and reloads and said a coefficient of variation - standard deviation as a percentage of the average - of 1% was match grade in pistol ammo, 2% was not bad, and higher was not uncommon.

Just for a fun comparison, the best load in my new .40-65 black powder rifle has a spread of 6 and a standard deviation of 2, at 1231 fps. And people wonder why the old guns are so accurate.

10 Spot Terminator
January 9, 2009, 11:34 AM
Looking at your chrony data my conclusion would be this,,,,

Buy American !!! Nyet on the Soviet !!! :D

edSky
January 9, 2009, 02:17 PM
I got an F1 about 16 years ago and it worked well until I "upgraded" to a Master F1 w/ remote... Best day was when it experienced a terminal ballistic event, and was replaced with a ProChrono Digital. The Chrony had to have bullets pass 3" or less above the sensors to read, absolute perfect alignment was a must or it was an error, and it was absolutely psychotic with regard to light. It did not matter with screens, no screens, xtra huge homemade screens, bright light, cloudy, sun angle...


Galil, I have had my brand new Chrony Beta for a week and took it to the range on Saturday. A beautiful sunny day, clear sky, etc.

What did you shoot yours with, how many rounds, and at what distance? Did you shoot the screens or rods first, or go straight for a vital organ?

I am determined to record at least one consecutive round before I give it a hot lead enema.

Galil5.56
January 9, 2009, 02:55 PM
What did you shoot yours with, how many rounds, and at what distance? Did you shoot the screens or rods first, or go straight for a vital organ?

Fairly solid 9mm 125 grain LRN impact, terminal velocity around 1100. Lucked out that it went through all sides, both sensors, nice exit hole... Wish it would have happened years earlier. In your crappy, staus quo Chrony situation, I'd just put a terminal hole in it and be done with it. New US made ProChrono = Chronographing pleasure so far.

If Comp electronics would come out with an IR or similar wireless remote, they would pwn the market.

Mello
January 10, 2009, 04:48 PM
kinser11,

What is the distance from your gun's muzzle to the first screen?

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