New to handloading and to 300 Black Out

[StanD]

Ok I was going to go to the range today to test fire my first 25 reloads , All are 1 fire Norma Brass fired by my AR. RCBS Die sized then loaded using Lee dies including FL Die.
This morning I got up all giddy to see how I did. I measured (for at least the 3rd time) each case for overall and head space and looked at the primers, everything was within a gnats ass so I got ready to load 5 mags with 5 rounds each according to charge. looking around I saw my powder scale. Hmmm I thought Ive never wieghed these things maybe I should do so and document the results. after doing so I see a tenth or 2 of varrience so I made a spreadsheet wieghing ech componant and adding them up then adding in the powder wieght and finaly subtract the "expected wieght" based on the componant and powder wieghts. I see my actual wieghts consistantly lower see below. The question is did I miss something here or am I being the typical over causous Noob? https://gyazo.com/8eee3d556af984431c603155441c03e9 Sorry I dont know why but I was unable to put the picture in but the gyazo link seams to work.

[Omega]

If you are weighing loaded cartridges, then that is to be expected. Weigh some of the empty brass to see that they can very a bit, same for projectiles, they can vary a bit as well.

[StanD]

Yes I weighed several of each component and .1 to .2 variance on the cases and projectiles. So I wieghed 5 of each and used the average and i expected a few tenths on the finished wieghts but I am consistantly at least 5.x to 6.x gr lower than I expected. I was super careful with the powder wieghts so its confuing to me that it is so high (low) my Scale is a cheaper one but I used the same scale for powder and then a few weeks later for the finnished wieghts and it apears consistant. Does barametric pressure or humidity affect the scales? I may buy a puller (was thinking it would be a good thing to have as a die. I have the hammer looking one but it doesnt look like it would be a clean job) RCBS puller and Collet will be her tomorrow because $40.00 is better than a squib or a bang BOOM. Its a learning curve and you have to have the right tools right.

[imashooter2]

What did you use to dispense the powder?

[dellet]

I would simply weigh each component, assemble those and re weigh. Then re weigh the cartridge again in a few days. Make sure you check zero.

There are things that can effect a scale, 5-6 grains is a candidate for the garbage can.