Help with chronograph data

[Bevenue]

I picked up a chronograph last week. Now need help with reading the data.
I can see I make PF(135500) with my 9mm load, but is it high enough for changing weather conditions? What about the ES and SD? What are they telling me about my loads?

Weapon: Springfield XD9 4"

Speer Gold Dot 124 +P: HI 1189, LO 1122, AVG 1162, ES 67, SD 21. 10 shot string
Montana Gold 124JHP 4.1 Titegroup: HI 1106, LO 1075, AVG 1093, ES 31, SD 11. 10 shot string



Weapon: S&W M&P340

Speer Gold Dot 125 +P: HI 808, LO 784, AVG 799, ES 24, SD 9. 5 shot string
Montana Gold 158JHP 3.5 Bullseye: HI 633, LO 591, AVG 603, ES 42, SD 19. 5 shot string
Montana Gold 158JHP 4.0 Bullseye: HI 701, LO 631, AVG 652, ES 70, SD 26. 10 shot string


If you need any other info, let me know.

 

[Shriner]

HI--your fastest round
Lo--your slowest round
Av-- average velocity of ALL rounds in that string
ES--the Extreme Spread of the string (fastest and slowest)
SD---the Standard Deviation of the string -how differant the velocity was for each round in the string
AD---the Average Deviation for the string

the smaller the ES,SD,AD the better your hits will be as the shots will be acting more the same for each one-than one having more recoil and next less

 

[Shriner]

What type of chronograp are using ? I use a Pact Md 1 with the old style skysceens.

 

[Bevenue]

I'm using a Competiton Electronics ProChrono Digital. I don't think it measures Average Deviation. Is there a way to figure it out by each shot?

Does it look like the ES & SD need to come down?

 

[tul9033]

I just chrono'd the MG 124gr JHP out of a G17 with 3.8gr of TG and got an average of 1042 for a 129 PF. My ES was 38 and SD of 14 which is ~3% of my average. I'm satisfied with that.
I try and give myself a +5 PF boost for any variances.
The ES and SD are just indicators of how consistent your loads are.

Here is a quote from gun tests on SD:

Standard deviation tells you how close you can expect the velocity of any shot you fire to be to the average velocity. Statistically, it's been proven that 99.7 percent of rounds fired will fall within three standard deviations above or below the average velocity. 95.4 percent will fall within two standard deviations above or below. And 68 percent will fall within one standard deviation above or below. For example, if our 20 shots generate an average velocity of 1,000 fps with a standard deviation of 10, we can bet the farm that almost every round of that ammo we fire out of that gun (99.7 percent) will fall between 970 and 1,030 fps. Similarly, 95.4 percent will be between 980 and 1,020 fps. And 68 percent will be between 990 and 1,010 fps. Now that's some meaningful data.

A small standard deviation is always a sign of ammunition that's been assembled with skill and attention to detail. By the same token, a wide standard deviation can usually be taken as an indictment of quality control. The more consistent the ammunition, the better the odds it will produce the exact same result, both in accuracy and terminally, every tim

 

[grwd]

What's with the +p designation with your loads?
These are your reloads, yes?
What is your aim for making a certain PF?
Are you shooting for competition?

 

[Bevenue]

What's with the +p designation with your loads? Factory loads from Speer (carry ammo)
These are your reloads, yes? The +P ammo is factory loads from Speer (carry ammo), The loads with Montana Gold bullets are my reloads.
What is your aim for making a certain PF? I have been shooting IDPA and have to stay above 125PF. With the .38SPl looking for factory power to a little lighter. Having trouble with running the numbers for it as most the websites and other shooters are checking velocity with a 4inch barrel.
Are you shooting for competition? Yes The 9mm I use for IDPA and once (so far) for USPSA.

.....

 

[grwd]

running 135 pf is plenty safe to where youd make 125pf min wherever you might have to chrono at a match. They look fine.