Extreme Spread - acceptable ranges

[gravityBad]

I haven't come across any info regarding acceptable consistentcy in loads with regards to Extreme Spread. I am using a Dillon 550b with a ProChrono and shooting 9mm. I shot 5 different loads today with an ES spread of 30,69,80,45. What are 'general' acceptable / unacceptable limits and should/could these vary by caliber?

Thanks,

Joe

[Jman]

Hi Joe,

Whats your muzzle distance to the chrono?

I believe 30-40 to be pretty good. Over 50 not so much.

[Sarge]

Hi Joe,

Whats your muzzle distance to the chrono?

I believe 30-40 to be pretty good. Over 50 not so much.

+1 30-40. Your big numbers are too much. However, I am more concerned with SD(standard deviation) than I am ES. It gives a much more useful? snapshot of your chrono readings. I get good results with SD's in the low teens but I always prefer single digits which can be hard to come by with all the variables in our loading process.

[gravityBad]

Hi Joe,

Whats your muzzle distance to the chrono?

I believe 30-40 to be pretty good. Over 50 not so much.

+1 30-40. Your big numbers are too much. However, I am more concerned with SD(standard deviation) than I am ES. It gives a much more useful? snapshot of your chrono readings. I get good results with SD's in the low teens but I always prefer single digits which can be hard to come by with all the variables in our loading process.

Thanks for the replys...

- muzzle distance is about 10-15 feet as indicated in the directions.

- here's how it breaks down:

ES 30, SD 11

ES 69, SD 27

ES 80, SD 34

ES 45, SD 17

ES 31, SD 11

I probably should mention my scale seems to jump around...even in a completely static environment,i can't even sneak up on it w/o it changing.

The scale won't hold a weight and will randomly vary between .1-.3grs. I assume this may be the root of higher deviation.

So, if you prefer looking at SD, what are the general acceptable ranges?

Thanks,

Joe

Edited June 13, 2010 by gravityBad

[Jman]

Variations in case capacity can explain your spreads easily. Load 20 with the same head-stamp and chrono. Betting your ES will shrink some.

[Jman]

So, if you prefer looking at SD, what are the general acceptable ranges?

Load dependent. My heavy bullet/fast powder can be under 20 SD. My light bullet/slow powder loads can be well over 40 SD. These are in the

169-175 major PF . All perform perfectly well for my USPSA pistol requirements. At our expected distances of 5 to 40 yards these number

don't amount to much. Just keep in the safe range and your good.

[Sarge]

I probably should mention my scale seems to jump around...even in a completely static environment,i can't even sneak up on it w/o it changing.

The scale won't hold a weight and will randomly vary between .1-.3grs. I assume this may be the root of higher deviation.

So, if you prefer looking at SD, what are the general acceptable ranges?

Thanks,

Joe

Digital scale? Any air movement at all. Even air movement you can hardly feel will make things fluctuate. Flourescent lights? They will cause problems too. Are you throwing at least ten charges and averaging them? What powder? Some meter better than others.

As for your SD's I'd say the 17 is acceptable but the 11's are what you want.

[gravityBad]

I probably should mention my scale seems to jump around...even in a completely static environment,i can't even sneak up on it w/o it changing.

The scale won't hold a weight and will randomly vary between .1-.3grs. I assume this may be the root of higher deviation.

So, if you prefer looking at SD, what are the general acceptable ranges?

Thanks,

Joe

Digital scale? Any air movement at all. Even air movement you can hardly feel will make things fluctuate. Flourescent lights? They will cause problems too. Are you throwing at least ten charges and averaging them? What powder? Some meter better than others.

As for your SD's I'd say the 17 is acceptable but the 11's are what you want.

Digital - yes...JS-100xV

I've used digital scales for other hobbies before and am aware how sensitive a digital scale can be w/ the slightest air movement (breath) and the many other factors that could account for a weight to jump around. The issue seems to be that the scale will jump around, similar to the case with air movement, but I have went to great lengths to rule this out. A completely static room w/ absolutely no air movement ,no computers, no cell phones, no noise or vibration can still yield a weight that may vary by +/- .1-.3gr when using the same piece. I can weigh a primed case ,lets say 60.5gr, zero the scale out and remove the case and the scale will read -60.2gr. It only gets more frustrating from there. Sometimes it will read the same case as 60.7 and then read 60.3 the next time ....w/o jumping around as though something is interfering with it.

Anyhow, seems as though that's a whole new can of worms. I will need to address the scale issue before I can know what to shoot for when it comes to ES and SD.

I'll try weighing w/o the florescent lights - thats the only thing I've heard or read that may play role in its inconsistent weight.

Hand + scale = crush into forehead!

Thanks,

Joe

edit: (took out where I bought the scale from as it has no bearing and was not intended as a negative comment)

Joe

Edited June 13, 2010 by gravityBad

[Sarge]

Yeah Joe, it might be time to try another scale.

[Alan550]

Another possibility is ANY fluctuation in the power, such as an air-conditioner, refrigerator or water heater turning on/off. Mine changes every time the heat pump comes on or stops.

Alan~^~

[gravityBad]

Another possibility is ANY fluctuation in the power, such as an air-conditioner, refrigerator or water heater turning on/off. Mine changes every time the heat pump comes on or stops.

Alan~^~

should i assume you have an AC scale? the one i have is battery powered. I received an email today and will try replacing the batteries even though the scale and batteries are new. If this doesn't work, i have a few options - replacement or upgrade.

Thnaks for all the replies

[Too_Slow]

Do you live near one or more broadcast towers (TV or radio) if so it could still be RF from them.

Brian

[GForceLizard]

I have the same scale http://www.eabco.com/electronicpowderscale.htm I place it on a non-running drill press or table saw so I have a stable base. This scale drifts as it warms up and it has an automatic shutoff so it can be a bit frustrating. Try letting it warm up. Figure out how long before it shuts off and keep turning it back on. I throw 10 charges from the powder measure to check weight, repeat until you get the same reading twice. If you are testing 10 charges the +/- .2gr is minimized.

Some powders will give you a better SD than others. Solo 1000 has been much better for me than Power Pistol. The worst SD I've had from Solo 1000 is 13.11 for Power Pistol my worst is 25.70 but 10% of my PP tests are under 10. Don't rule out good technique with the chrono either. It's a bit of an art to get good chrono readings.

One day I will spend the money on a better scale. For now, warm up, weight 10, repeat.