Weight variance in monometal bullets

[HARPERC]

It might depend on which brand you have? Mine is horrible for repeatability. I have a cheap Frankford Arsenal digital scale.

All of the "affordable" digital scales Ive seen have a tolerance of +/- .1gn, so the rounding error could stack up with repeatability issues up to .2gn. IMO there's no way a scale with a tolerance of +/-.1gn can be used to weight cnc machined bullets accurately.

When I started handloading I got the Frankford Arsenal scale (iirc 40 bucks), it took me a while to learn it was holding me back. Huge standard deviations and ES. Ive heard that temp changes can affect readings, using it under flourescent lights/electrical interference. I started cluing in on whats going on, did some tests where I put a weight on it and wrote that down, then came back 10 minutes later and half the time it would be another .1gn different. Same results measuring the same thing the next day. Then Id press on it and let go and it wouldn't return to the same value. To me, that right there meant I could never trust it.
I bought an analog scale and haven't looked back (though I discovered "parallax" is what affects analog scales but no where near off like cheap digital scales)

Id be curious what you find testing repeatability in your digital scale.

Its amazing when every part of everything thing from firearm to to target, and in between is dependent on tolerances. When they match up, all is golden, when they don't.......

 

[dfanonymous]

Its amazing when every part of everything thing from firearm to to target, and in between is dependent on tolerances. When they match up, all is golden, when they don't.......

It's like that in a lot of trade jobs too. Difference between a framer, a cabinet maker and a furniture maker is tolerances. They're all carpenters.

 

[Koda_]

Its amazing when every part of everything thing from firearm to to target, and in between is dependent on tolerances. When they match up, all is golden, when they don't.......

I wasted a lot of time and money on components learning to handload with that digital scale. A lot. Try being new and all your groups in your first OCW test are bad, velocities all over... lol. So you go back and do it again, same results. It wasn't until I bought an analog scale that I got better groups and found my first accuracy node. I still had a lot of inconsistencies elsewhere, but charge weight is a big one. Frustrating, but lessons learned make us better.

 

[cornstalker]

I sure appreciate the input. The result is truly a non-issue, but by asking the questions I learned from the experience of others. Thank you.

 

[cornstalker]

I should clarify. The results of my measurements showing variance is a non issue. The results of the conversation was a challenge to my perspective. Learning occurred, which was the desired result. Thanks again to all of you who responded!

 

[Koda_]

The results of the conversation was a challenge to my perspective. Learning occurred, which was the desired result. Thanks again to all of you who responded!

When I started reloading I had no mentor. Most everything I learned was on reloading forums in discussions like this.

 

[wldcat]

Spiked my curiosity so I grabbed a box of absolute hammers and weighed 10 at random on my fx-120. Similar results as op. And like op said it doesn't create any problems they still group amazing

128.88
128.72
128.64
128.66
128.82
128.66
128.72
128.82
128.82
128.68

 

[Culpeper]

Spiked my curiosity so I grabbed a box of absolute hammers and weighed 10 at random on my fx-120. Similar results as op. And like op said it doesn't create any problems they still group amazing

128.88
128.72
128.64
128.66
128.82
128.66
128.72
128.82
128.82
128.68

Lab grade scale. I think the subject matter is a proven non-issue on weight quality control.

I sure appreciate the input. The result is truly a non-issue, but by asking the questions I learned from the experience of others. Thank you.

 

[Culpeper]

It might depend on which brand you have? Mine is horrible for repeatability. I have a cheap Frankford Arsenal digital scale.

All of the "affordable" digital scales Ive seen have a tolerance of +/- .1gn, so the rounding error could stack up with repeatability issues up to .2gn. IMO there's no way a scale with a tolerance of +/-.1gn can be used to weight cnc machined bullets accurately.

When I started handloading I got the Frankford Arsenal scale (iirc 40 bucks), it took me a while to learn it was holding me back. Huge standard deviations and ES. Ive heard that temp changes can affect readings, using it under flourescent lights/electrical interference. I started cluing in on whats going on, did some tests where I put a weight on it and wrote that down, then came back 10 minutes later and half the time it would be another .1gn different. Same results measuring the same thing the next day. Then Id press on it and let go and it wouldn't return to the same value. To me, that right there meant I could never trust it.
I bought an analog scale and haven't looked back (though I discovered "parallax" is what affects analog scales but no where near off like cheap digital scales)

Id be curious what you find testing repeatability in your digital scale.

These cheap scales get by using calculated weighted averages over time only to find out they are within the advertised error rate. Apples and oranges.

 

[Hand Skills]

swagged or cast hmmm yes vastly different

I would think I better get my words correct
Yes muppet moment from me thanks for pick up
Cheers

Careful who you trust, Fordy!

Ya, I misspoke there - definitely a cold process.



Thanks for setting us straight @dfanonymous

 

[cornstalker]

Spiked my curiosity so I grabbed a box of absolute hammers and weighed 10 at random on my fx-120. Similar results as op. And like op said it doesn't create any problems they still group amazing

128.88
128.72
128.64
128.66
128.82
128.66
128.72
128.82
128.82
128.68

Thank you for doing that.

 

[wldcat]

Anyone think the oil in the tips of the hammers would affect this ? I'm thinking it's such a small amount that the scale wouldn't pick it up but if you guys think I'm wrong I'll run the test again with out of the box bullets and then clean them and weigh again

 

[khmplus]

Spiked my curiosity so I grabbed a box of absolute hammers and weighed 10 at random on my fx-120. Similar results as op. And like op said it doesn't create any problems they still group amazing

128.88
128.72
128.64
128.66
128.82
128.66
128.72
128.82
128.82
128.68

Biggest spread is about 0.2 percent. If you aren't weighing powder to less than 0.1 grains (6 milligrams), that's about the same amount of error. For the same energy (powder), a change in weight is proportional to a change in square of velocity. The weight difference of 0.24 grains above would equate to about 3 feet per second difference in velocity. Puts it in perspective for me.

 

[Koda_]

Anyone think the oil in the tips of the hammers would affect this ? I'm thinking it's such a small amount that the scale wouldn't pick it up but if you guys think I'm wrong I'll run the test again with out of the box bullets and then clean them and weigh again

I dont think so, the oil has never affected their accuracy.
I thought I heard they changed their process to clean out the oil so if true it wont matter anymore.