Safety checks

[NC FNS]

Random thought - don’t weights vary as you move farther from the equator? If so, I wonder if you need to adjust loads or not.

[hounddawg]

A charge would weigh .05 percent less at the equator than at the true north pole. For a 40 grain charge that would equate to (pun intended) .02 grains. Adjust accordingly

[Unclenick]

Originally Posted by USSR

The Quarter is not a good candidate for use as a weight check. For one, it's weight is completely outside of normal powder drops, whereas a dime falls nicely between handgun drop weights and most rifle drop weights. Also, there is not the variance of designs, thereby resulting in weight variances, that is found with Quarters. For guys using balance beam scales such as myself, the dime works well. Just MHO.

The problem is an electronic scale calibrated by a single weight will alter its load cell output multiplier (gain slope), not its offset like a pan balance will. So it's the percent of error, not the absolute error that matters, and if you look at standard check weights, you see they have a smaller absolute error as the weights get smaller, too, and for the same reason.

I grabbed a fist full of dimes out of my car's tray (always packed with coins) and started weighing them. They varied from 34.11 grains to 35.52 grains, or about a 4% spread. The quarters measured above had about a 3.7% spread, so, for randomly chosen coins it is probably a wash as to which one you use to calibrate an electronic scale. A beam balance is another matter. On that, the error will be an offset, so there the fact that 4% of a dime's weight is less than 3.7% of a quarter's weight will be an advantage.

To try to tighten the dime calibration idea for you, I selected thirty of only newer and sharper looking dimes and weighed those. That narrowed the spread to about 2.5% of the mean, so you can cut the absolute error not quite in half by sticking to recently minted, unworn-looking dimes, and that is certainly worthwhile. For that thirty, I got:

High:
35.52 grains

Low:
34.64 grains

Mean:
35.03 grains

Standard deviation:
0.21 grains

Extreme spread:
0.88 grains.

The U.S. Mint says the target weight for new dimes is 2.268 grams (35.00 grains), and that certainly agrees well with my result. For quarters it is 5.670 grams (87.5 grains) which isn't too far from my result for quarters, either, though it is less precise than what I got for dimes, both in absolute and percentage-wise terms).

A couple of lessons seem apparent to me from this. One is to select only the new and sharp looking dimes. Weigh 30 and pick one out of the thirty that is closest to average and keep that for your calibrator. As I mentioned earlier, you can take it to the pharmacist and ask for weight confirmation. If his scale doesn't have grains (it should) the conversion factor with more than enough decimal places to go from grams to grains is to multiply by 15.43236.

As a general FYI, most of the check weights sold by powder scale makers seem to be class 6, below.




NC FNS,

Gravity is greatest where mass is greatest, less about 0.3% for the earth's spin at the equator, less another 0.2% for the equatorial bulge, so about 0.5% less weight at the equator than at the poles. So a 40-grain charge would be off about 0.1 grains low at the pole and 0.1 grains high at the equator using an uncalibrated absolute weight scale like a spring scale. But the mass effect is also in play, and gravity actually varies a total of about 0.7% over the whole earth's surface. NASA has maps of just the mass gravity from the GRACE satellite readings (the satellite isn't rotating with the equator so that centrifugal effect is absent from the maps). At the top of a big mountain, where there is mostly rock under you, gravity is greater than over the Marianas Trench, where there is mostly water under you (rock is denser than water, which why it sinks).

The great thing about a balance is, it doesn't matter what the gravity is. It just compares the mass on one side of the poise to the mass on the other side. So it actually measures mass and not weight. The same thing happens with your electronic scale when you use a check weight to calibrate it. The check weight weighs less at the equator so the scale winds up compensating for the gravity difference via the check weight.

[cw308]

Good Post . I must admit , most of the time I lay the pan on the scales , turn them on let them zero and that's it . If they start to roam I will calibrate using the check weights . RCBS ChargeMaster 1500 and GemPro 250 . Easy enough to drop a check weight into the pan . Thanks for the what if .

Chris

[hounddawg]

I still think a well made beam with a needle and a webcam mod is the most accurate scale you can get for less than $1000. But is certainly not the fastest. I throw .1 low and trickle up with my fingers and can get about 1 round per min filled and seated but that took a lot of practice. When placing the pan or dumping the thrown charge in you have to wait for the for the pan to stop swinging takes time. They are extremely sensitive to the slightest air moment also and and the draft sheild's I rigged up tended to be clunky

Electronics used the same way are much faster and their draft shields are more user friendly

[RC20]

I have been posting for several years about using the pan as the check weight.

Per Unclenick, the pan weights around 130 grains (plus or minus depending on where it came from, mine are off old beam scales because they are nicer than the chap ones you get with the powder dispenser)

If its non linear, its going to show quickly as those pan weights are about twice what anything I shoot are (and higher than any load I know other than a 50 BMG)

If the zero (tare) goes off then I zero it again and it needs to return to .1 of what I know the pan weight is.

Frankly a bullet is a good check as well, zero the scale, bullet will be withing a few tenths. Some withing .1

[Nick_C_S]

Unclenick is obviously a patient man. Is there nothing he'll do to advance the value of a thread?

We should all be grateful.

Back to the tread: Not to be redundant, but the time I spend setting up the scale and calibrating it to where I am completely confident it is giving me accurate information is of the utmost importance in my loading process. No time expense is spared.

[HiBC]

My old Ohaus has served me well.

I'll agree checking calibration is wise.

I'm skeptical that a 2 gr overcharge of an otherwise safe load would scatter a Redhawk all by itself using appropriate 44 magnum powder,such as H-110

I know I would not want to operate that close to the edge.

Just my unverified opinion.

[RC20]

Unclenick is obviously a patient man. Is there nothing he'll do to advance the value of a thread?

We should all be grateful.

He is amazingly

and I am grateful.

I may disagree (and have been very wrong!) or I may do it differently because it suits my brain, but a fount of good solid info without any question!!!!!!!!!!!!!!!!!!! - and the patience that many Saints could have used.

[reynolds357]

I am betting a double charge blew the revolver. I have seen Rugers and Dan Wessons handle double charges. I doubt 2gr over would blow anything but a Sat. night special.

[RC20]

This of course is all just conversation with clerk not the actual guy. The staff at midsouth are great people and will help you with problems so it was another customer. I took a pic of it but have idea how to share it with the group.

2nd hand information is not the same as first hand (it can be or it can be really bad)

To the best of my knowledge, in my early Ruger 44 magnum shooting days, I had a squib and in a moment of loss of situation awareness, I pulled back and lit off another one.

Other than a nice bang nothing bad happened.

What it would take to blow one up? Double charge + and the fastest powder you can buy is my take. But then that is my take.

Full case of Unique?

[hounddawg]

My take is only if the load data was bad would a .1 overcharge do any serious damage. I run my load from medium to hot and never seen so much as moderate pressure signs at max load and I have done quite a few workups. There was one exception but I am convinced that load data was faulty at the source

[walnut1704]

This is one of the reasons I prefer fixed-disk powder measures. I record the cavities used for loads, so the scale is just a double-check that I have the right cavity.

[HiBC]

Whatever works for you!

There are loyal users of such powders as Bullseye,for economy and good,accurate shooting. I have nothing negative to say about it.

I prefer to use powders with better load density. Its just not possible to accidently put a double charge of h-110 or 296 or 2400 in a 44 Magnum case especially since I always do a visual powder level check.

I don't like grossly overbore rifle cartridges either...as case capacity gets larger and bore dia gets smaller, things go wrong faster.

Generally,with a well designed modern cartridge...I'll use 308 and 5.56 for example,,if we choose the medium burn powders...we MIGHT be able to stuff enough in the case to blow a primer or stick a bolt....it still pays to load safely.

But likely the price we pay for an overload that is not obviously compressed ...we scrap our brass to loose primer pockets,or we can tell the load is too hot and we pull bullets.

Few of my powder selections leave powder room to blow up a gun.

I'd almost always have to admit I used the wrong powder if I blew up a gun.


Following a process(read the label out loud twice,one powder on the bench,etc) will pretty much prevent the wrong powder.