weighed powder charge workflow

[rodregier]

draft design for weighed powder charge workflow using a digital scale:

- pre-warm up digital scale for increased calibration stability
- Calibrate digital scale

repeat:
- place case on scale
- zero scale (tare weight)
- remove case, place under volumetric powder measure
- throw 'short' charge
- place case on scale
- trickle powder into case until goal charge acheived
- place charged case in loading block

I'm assuming that since I'm not weighing to a zero that I'll avoid the scale "hunt for zero" behaviour.

I'm hoping to avoid using a funnel with the case and trickler since it complicates the weighing operation. Brass would be .308 Win, so the case mount is not tiny.

I supposed I could find a small, light funnel and "tare" that out with the case too. Inverting the funnel and placing the case mouth on top of that to make a stable assembly to weigh would work.

Any small, light funnel vendor/part number suggestions?
(Needs to be light since the scale has a weight limit).

Comments?

 

[ranger335v]

Alternative Plan:

Set the digital scale under your bench.

Place primed cases in a loading block, mouth up, and place any powder funnel on the first case.

Set measure as you discribe, fill a good trickler (Redding).

Place any beam scale on the bench, at eye level, and pre-set it to your charge goal. (You will need no warm up, there will be no drifting, no calibration problems, no tare.)

Dump a light chage into the pan and place it on the scale. Trickle power up to weight, dump it into the funnel.

Step the funnel to the next case and repeat until done.

Look into the completed block of charged cases. Check for any powder columns that have charge variations or were missed.

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IF you simply can't live without that drifting zero, unreliable digital scale get one of Lyman's one piece pan/funnel tools and follow your current plan. Use your beam scale to check for calibration changes, often.

 

[Sport45]

.308 is pretty small to try to trickle powder into. If you're going to tare your scale with each case why not tare it every time you put the empty pan on? That way you could trickle into the pan and then dump the pan into the case through a funnel.

My process for 30-06 is more like this:

1. Plug the scale in and let it warm up while I
2. Get the powder measure out and clamp to bench
3. Get out loading block and place prepped and primed brass in upside down
4. Get powder from bedroom closet and bring to workbench
5. Pour powder hopper ¾ full of powder replace lid on powder bottle
6. Calibrate scale
7. Tare case and throw a charge
8. Dump powder back in hopper
9. Throw another charge and dump in hopper
10. Throw another charge and weigh case
11. Adjust powder measure
12. Repeat steps 7-11 until weight is +/- .2 grains from desired
13. Place case right side up in block
14. Tare next case and throw charge
15. Weigh case. If within desired range place in loading block right side up, otherwise go back to step 8
16. Charge next 6-12 cases
17. Repeat steps 14-16 until done, keeping powder hopper at least ½ full.
18. Inspect cases in load block with flashlight or sunlight to verify consistent powder level
19. Take load block to press and insert bullets in cartridges
20. Bag and label cartridges.
21. Pour powder back into bottle, recap and take to closet with new cartridges
22. Put away scale and powder measure

Whew, that was a lot more steps than I thought…

 

[rodregier]

Sport45: I'm looking for precision to level of scale resolution, not +/- .2 grains. .308 Win for 800 meter usage, trying to push to the next level of accuracy. My sources tell me that beyond 600 meters I need to go to weighed powder charges.

Your suggestion of throwing to a pan, trickling up and dumping thru a funnel has much merit. I should have ordered a funnel when I purchased the powder trickler. Picked the Hornady only because the vendor I used only sells Lee and Hornady reloading products. Added on to a projectile line item that was the primary focus of that order.

It always seems more complex when you have to write down all the steps

 

[rodregier]

Ranger335V:

Great tip on the Lyman combo pan/funnel product. Really reduces the fumble factor and speeds up the workflow. Just put one on order.

I don't personally like balance beam scales for powder weighing because I find them fussy to use. They can give an accurate measurement, just not my "cup-of-tea".