Powder variance

[glenns]

I just started reloading 12 GA shotshells with a MEC 600 Mark Jr. The recipe I am loading calls for 17.5 grains of Alliant Clay Dot. I've measured all 25 shotshells I've loaded so far trying to get 17.0 grains (thought I'd use this as a target amount to allow for variance - does that make sense?).

When I weigh the amount of powder in each shell I get actual amounts of 16.8 grains to 17.1 grains. Is a variance of .3 grains 'normal' or within reasonable thresholds?

 

[NCsmitty]

Welcome to THR, glenns.

Yes, it's not uncommon to have that variation, especially just starting to load. As your rhythm becomes more routine, the loads will become more consistent. Absolutely nothing to worry about.
Good luck.

NCsmitty

 

[243winxb]

Is a variance of .3 grains 'normal' or within reasonable thresholds?

Yes, this is normal. You will see larger variance with different types of powders. How the press handle is worked will also change the weight of the charge. Always check the powder charge as you cycle the press thru its many stations.

 

[Jim Watson]

That is very close measuring for the typical shotshell loader. I would take a .3 grain spread on about anything except match rifle ammo where a little velocity variation means vertical stringing or a powderpuff pistol load where it would be 10% of the load.

Carry on.

 

[loadedround]

As said previously any variance in the operation of a shotshell press will lead to charge fluctuations and it is nothing to be concerned about. In addition you will find that individual bushings will not throw the exact charge as indicated on your bushing chart, again nothing to be concerned about. Good loading.