Calculating Carbon/Resin Ratio of the Composite Pivot Tubes

Target proportions for carbon to resin is 50:50 by weight. Let's see how I did.

19.7mm X 10mm X 49mm weighing 15.2 grams
Tube volume = 11.1 cc
Tube weight = 15.2 g
Tube density = 1.37 g/cc

Carbon density = 2.27 g/cc
Resin density = 1.18 g/cc

Density tube = (%Carbon)(2.27) + (%Resin)(1.18)
1.37 = x(2.27) + (1-x)(1.18)
x = .175
17.5% of the density (volume) was made of carbon
82.5% of the density (volume) was made with resin

To change that to weight, not volume:
Carbon: 11.1cc x 17.5% x 2.27 = 4.4g
Resin: 11.1cc x 82.5% x 1.18 = 10.8g

From my approximation, this part has a carbon to resin ratio of 29% to 71% by weight. Not great.
Did I do that wrong? Correct me in comments and I'll reward you.

22.6mm X 14mm X 45mm weighing 17.9 grams
Tube volume = 11.4 cc
Tube weight = 17.9 g
Tube density = 1.57 g/cc

Carbon density = 2.27 g/cc
Resin density = 1.18 g/cc

Density tube = (%Carbon)(2.27) + (%Resin)(1.18)
1.57 = x(2.27) + (1-x)(1.18)
x = .36
36% of the density (volume) was made of carbon
64% of the density (volume) was made with resin

To change that to weight, not volume:
11.4cc x 36% x 2.27 = 9.3g Carbon
11.4cc x 64% x 1.18 = 8.6g Resin

Now that is interesting.
The main pivot shows a carbon to resin ratio of 52% to 48% (by weight).
Right where it should be.
But why so different from the link pivot when they were made side-by-side with identical processes?

I'll look more into the numbers for potential mistakes.