Another bit of detective work by Austen....

This is a cross-section of a Chinese made PVC bolt shaft. Note the lighter color(s) just below the outer skin. This indicates poor quality control during the molding process. I have found small air pockets in a few broken bolts. Again, it shows the need to set aside the bolts that don't shoot well.

I aquired an inexpensive digital gram scale to weigh the components of the factory bolts.
The scale will be necessary to finish the ballistic pendulum project here.

Ten steel points from the aluminum shaft bolts were weighed.
All ten weighed 45.4 grams for an average of 4.54 grams
Individually:
1 weighed 4.2
7 weighed 4.4
2 weighed 4.6
About 9.6% difference between the extremes.

Eight of the plastic tail assemblies weighed 23.4 grams for an average of  2.9 grams each.
Individually:
3 weighed 2.9
4 weighed 3.0
1 weighed 3.1

Please don't get the idea that these crossbow pistols are not worth buying. I love mine, and it really wasn't much work to tweak them up. ~Bill