Grains of powder accuracy difference

[BMG]

I have an 'aeADAM PGW 153i Max150g d=0.001g' electronic weighing scale that measures to 100th of a grain of powder. After recalibrating the machine (registers zero) I put my powder pan on (that measures 151,64 grains) and set the scale to zero. When the powder pan is taken off the machine it then indicates a moving figure any where between 151,56 and 151,66 grains shifting constantly within 151,56 to 151,66 range (I have a glass surround around the scale platform to protect against drafts). I require a weight of 37.4 grains of powder. So doing some maths my weight will show any where between dead-on and .1 of a grain difference in accuracy depending on when I put the powder pan on the scale.

My targets will be no longer than 300yds away. My question is: should I be worrying about the .1 of a grain discrepancy in accuracy of my powder to the accuracy of bullet placement on the target?

Thank you for your comments in advance.

Kind regards

BMG

 

[spclark]

What cartridge?

With a forum handle of BMG & you're only shooting to 300 yards... .1 grain won't register on your targets much.

Digital scales for weighing powder are as much a curse as a blessing. Make SURE there's no fluorescent lights within 20' (new compact models may be OK as rheir ballasts are electronic, not coil-type) or on the same A/C circuit you have your scale plugged into. Leave your scale on all the time or if you don't want to turn it on at least 30 minutes before use. Leave cell phone behind (cordless types too) when you weigh charges.

I use a Denver Instruments model with the same specs as yours & routinely see .02 - .06 grain variations depending on the time of day. I attribute this to line demands on my power supply from the mains. Re-zeroing the scale almost every time I set the brass pan on it helps... some.

With patience & practice I'm confident I can load charges to +/- .01 grain though even out to 1,000 yards I can't hold hard enough to trust I'd see the difference on paper.

 

[jlow]

I think when you remove the scale, you drop the weight on the scale by 150 odd grains which is quite a bit off from where it was calibrated and so this is not a good test of the accuracy and precision of the scale. What is a better test is to measure your powder weight a couple of times to test consistency if you are worried. I normally do this not only to check consistency but any brain fart that I might have.

What I normally do is to first weight the case with the primer first, weight the powder, and then weight the combination. The difference between the ((case + primer + powder)-(case + primer)) should be close to the weight of the powder – sounds complicated but it is all done on Excel. My scale a GemPro 250 (reviewed on this board) usually gives me a weight which is 0.04 gr of the correct weight. If it is off more than that, I pour the powder back into the pan and adjust if necessary – it is rarely necessary.

Usually when I am off it is because the original weight of the case + primer was off a bit and the final combo weight was also off a bit in the same direction which gives me a combination weight which is seems off by more than 0.04 gr but weighting the actual powder shows me there is no problem.

 

[TheSnake]

Digital scales for weighing powder are as much a curse as a blessing. Make SURE there's no fluorescent lights within 20' (new compact models may be OK as rheir ballasts are electronic, not coil-type) or on the same A/C circuit you have your scale plugged into. Leave your scale on all the time or if you don't want to turn it on at least 30 minutes before use. Leave cell phone behind (cordless types too) when you weigh charges.

I use a Denver Instruments model with the same specs as yours & routinely see .02 - .06 grain variations depending on the time of day. I attribute this to line demands on my power supply from the mains. Re-zeroing the scale almost every time I set the brass pan on it helps... some.

I agree with spclark on the scale and interference. My scale is not as costly as yours and I leave it on all the time. At times, it will bounce back and forth between .0 and .2 grains just sitting there in it's resting spot on the bench. I slide it forward away from the wall at the back of the bench, and it will settle down.

I would also consider a power line conditioner or battery backup with power conditioner built in.

Now with the cost and expectations of your scale, if I could not get it to settle down by eliminating all interference and adding the line conditioner, I would be calling the maker looking for some relief. With a 100th of a grain cost, I would not settle for a 10th of a grain performance.

 

[jlow]

The cheaper digital scale usually will give you problems and is the source of much of the frustration on the web from people switching from beam balances. However, it’s the old you get what you pay for.

The good quality scale like the GemPro 250 (and others reviewed on this board) usually has no problem keeping a zero and if it is occasionally off, it is not by more than 0.04 grs – I say this with two years of experience with this scale and more than 10 years experience using professional digital scale in the lab. The biggest problem with digital scale (the good ones) is not letting them warm up long enough and static. The latter can be tamed by wiping down the pan with dryer sheets.

 

[Catfish]

I have never used a ditigal scales, but can tell you that a charge varation of .04 gr. will have an unmeaureable effect on accuracy, even if bench shooting.

 

[jcampbellsmith]

http://bulletin.accurateshooter.com/2011/04/ten-commandments-for-use-of-electronic-scales/

is good reading.

Commandment 11 is to keep well away from mobile phones and wifi. Regards JCS

 

[CoverDog]

BMG....you say your current scale is able to read to .001g. ,when converted to grains that makes it accurate to 2/100th's of a grain, not 1/100th of a grain.

Secondly, you say "So doing some maths my weight will show any where between dead-on and .1 of a grain difference in accuracy depending on when I put the powder pan on the scale".

For what that scale cost, you should be able to place your powder pan anywhere on that 4.9"x 5.7" scale pan and get the same reading time and time again.

Finally you said " My targets will be no longer than 300yds away. My question is: should I be worrying about the .1 of a grain discrepancy in accuracy of my powder to the accuracy of bullet placement on the target?"

Many short range shooters <200yds after adjusting their measure for a certain weight just throw their charges . At 300yds it will show, but not nearly as much vertical as would be visible at 1,000yds.

IMO for what you have $$ in your scale, it's letting you down.

 

[BMG]

Thank you all for your kind responses.

Tomorrow morning I am going to phone the manufacturer to enquire about the shifting readings.

I do not keep the scales plugged in all the time but I do allow around an hour before I use it and I will take into account all your advice regarding other electronic influences and static.

The information regarding accuracy was very helpful i.e. accuracy out to 300yds will not be affected too much.

Kind regards

BMG

 

[Leaddog]

.1 of a grain isn't going to make a measurable difference at 300.

Get your scale checked out. You have a good scale using force restoration technology and should be solid without drift.

 

[artbosco]

My question is: should I be worrying about the .1 of a grain discrepancy in accuracy of my powder to the accuracy of bullet placement on the target?

1/10th of a grain? None what so ever.

 

[TheSnake]

My question is: should I be worrying about the .1 of a grain discrepancy in accuracy of my powder to the accuracy of bullet placement on the target?

1/10th of a grain? None what so ever.

How about 2/10th of a grain? If his scale is fluctuating, it could be off by 2 depending on the swing. Where do you draw the line? To me, it's somewhere below his 1/10th.

 

[FroggyOne2]

I know that a lot of the guys that I shoot with feel that I am a lil anal in my reloading, but picking an sorting kernells of powder is going a lil overboard I believe!

 

[in2deep]

yeah they have medication for OCD people that sort kernels with a jewelers loupe... (it's no cure and barely takes the edge off).

of course if you spend a grand on a 3 decimal place scale not sorting kernels by length may be an injustice to your equipment and bring bad ju-ju on match day.

 

[FroggyOne2]

;D

 

[Peter N]

In my experience seating bullets with consistent neck tension and Depth has more of an effect on accuracy than does a slight variation in powder weight.