Weight variance in monometal bullets

[maximini14]

What factors would contribute to weight variance in machined bullets?

The numbers I came up with are so small that they are of no consequence, so please do not misunderstand my intent here. I just honestly expected precision-machined bullets to weigh the same. What would contribute to them varying a tiny amount in weight, and how could it do so without changing the dimensions of the bullet unless it was in the hollow point cavity? I am not knowledgeable about machining processes and reasonably expected variances.

I do not have a scale that goes down to the hundredth of a grain, only tenths. I weighed 15 of each of the following on a Dillon and an RCBS digital scale. The two scales yielded the same results.
.308"
181 Hammer Hunter- .2 grains spread
180 Sierra Tipped GameKing .3 grains spread
190 Barnes LRX .5 grains spread.

I was really surprised to see the Barnes have a wider spread than a cup and core bullet.

I use Barnes 150gr ttsx in my 06 rem pump.
I weigh ea bullet and put in different bunches of 20 . I get half inch groups.

 

[Lenny Foffa]

My 130 Grn Ballistic tips usually vary between 129.8 and 130 .1 . I have found little to no difference in average Groupe size, at 100 yards, from my light 270!!! This seems adequate for Deer Hunting. For a time, in prepping for a BR match, I was told that I needed to measure Berger Flat Base target bullets, from Base of Bullet to Ogive of Bullet and I got so many different numbers I stopped doing it. It became terrible for me. I just went back to separating bullets and cases by 1 /10th of a grain.