Thursday, June 4, 2009

Reloading tip: Beware the powder measure knocker!

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The old Lyman Ideal powder measures from the early 1900's had a neat little widget on them. It was nothing more than a tiny metal bar, or hammer, hinged on the side of the powder measure. In use, the reloader raised the bar once, allowed it to fall and hit the measure a sharp rap, and then he threw his charge. The mild impact and vibration settled the powder in the measure, giving a more compact and consistent charge. The old timers knew what they were doing, as even to this day good reloaders know to be consistent with operating the handle when they throw a charge.

It's this ability of most powders to settle with vibration that can cause a problem. If,
like many reloaders, your powder measure is mounted to the bench along with the press, then each throw of the press handle can act as a 'powder knocker', settling the charge in the measure. This throws a random action into the job of measuring the powder charge, and inconsistent charges can play havoc with accurate ammunition.

If the measure is set to throw a maximum charge for a load, or is stocked with a very fast powder such as Bullseye, then the extra powder compaction can cause the thrown charge to be over the limit.

It's good practice to throw every charge of a set one after another, and then seat bullets in the case. The first few powder throws should be made into a clean container and dumped back into the reservoir. Never to be forgotten... check the occasional powder charge on a good quality scale to ascertain the measure is doing a consistent job and the settings have not drifted.

If the powder measure is left stocked with powder for some reason, it's always wise to begin the next loading session by throwing a few charges to be dumped back in.
My personal practice is to do so, but refrain from dumping the last sample thrown into the reservoir until after I am done charging the case set. I think even the act of pouring in a few grains of powder can settle the powder column, even if only a little.

Careful consistency is key!

7 comments:

LI Mike said...

What does it hurt to first weigh and sort the cases into consistent batches, then do QA on each primed and charged case by weighing them? I suspect that most handloaders aren't loading hundreds or thousands of cases at a time. In just a few minutes you can QA a hundred such rounds. If the round doesn't meet spec then dump the charge and do it again. Am I wrong?

AKA Angrywhiteman said...

Mike, I don't follow your reasoning. The post is about charge weight, (powder), not finished cartridge weight. Why would I want to assemble a cartridge not knowing the weight of the charge beforehand?

I reload a good deal and follow the thread of thought behind the knocker and powder settling, increasing the weight per volume.

I can't follow your reasoning.

LI Mike said...

Angry, I am not disagreeing with the post. Its fine. What I was suggesting, but probably didn't express well, is running either all or some subset of cartridges thru the scale when it has been primed and powder loaded. I assume the brass and primer will vary by only a few tenths of a grain in a given batch if sorted right (factor x). So the addition of powder (factor y) will bring the weight now up to x + y. If you were to see such a cartridge at several grains difference that would be a red flag. Depends on the tolerance level we are aiming for. When all cartridges meet spec then do the bullet seating.

I hope this clarifies my thinking. Still appreciate the feedback.

AKA Angrywhiteman said...

Mike

It can be done in that manner, however I find it more expedient to adjust the powder dispenser to the desired charge weight, and throw a test charge every fifth or tenth case to check if I'm within specs.

I use a magnetic dampened beam scale, and weighing a charged case without a projectile raises the chance of a dropped case and spilled powder. The powder pan wasn't designed to hold a case upright.

With the digital scales, it may be feasible, but sounds like a lot of extra work.

There are good reasons to batch your cases by weight, especially if you are loading match grade ammo, because heavy cases have less volume and produce greater pressure with the same charge, which changes velocity, which changes in flight time, which changes point of impact.

For the shooting I do, it is enough to separate the military brass from the commercial brass, and load the military brass a little lighter due to the decreased volume.

Carteach0 said...

The only times I have weighed entire cartridges was when I suspected a light/no charge from my progressive press.

There is a value to separating cases by brand, weight, and volume depending on what kind of shooting is being done, and what kind of load.

For my pistol shooting, I do not segregate cases unless It's a maximum charge for critical use. For rifle, light plinking loads do get segregated cases. Most everything else does.

If I was going for bench-rest type accuracy, I would not only match cases by lot number, but weigh each case as well.

Buckshot said...

Carteach0,

I use a turret press (Lyman Spar-T or Herters 243 Super) and load one cartridge completely at a time.

Turret head takes a full revolution for each cartridge (or sometimes primer seating through loaded round if the cases needed tumbled.

In any case, the powder measure, also mounted on the turret, gets a full set of the same treatments with each cartridge.

I just have to perform the same movements WHILE WEIGHING THE CHARGES ALSO.

BTW, I use Lyman #55 powder measures turret mounted with the use of an adapter to bring their drop tube threads up to 7/8" X 14 tpi standard thread. I NEVER use the knocker, though it does throw around some when the turret is indexed.

Been doing this for over 35 years for both rifle and pistol cartridges and never had any trouble.

Gives me a "semi-progressive" in that I must index it, but it also gives me time between the steps to check the powder level by eyeball and pull the case and check for primer seating depth if anything felt strange that time.

Anything can be repeatable, as long as you do it in the same way each time.

Buckshot

Carteach0 said...

Buckshot,

I like the idea of the semi progressive Lyman turret. One day I will have one on my bench too.

Some years ago I acquired one in a batch deal to be turned over for profit. I made a point of not trying it out, as I knew I'd never give it up if I did.