Second batch of jsb's I buy with the same flaw... One was. 22 25gr monsters, and now 15.89 gr.
There's a barely noticeable indentation about halfway round the pellet head.
In normally take my vernier with when buying pellets to measure head size but didn't notice the head deformation.
Pellets on top with deformation and bottom the good batch. Both measure 5.52 head size.
Difference in accuracy at 36 m is significant ... Top target I turned the velocity down about 25fps after each group from 950 fps just to see what velocity is the most accurate.
The upside... I don't feel bad doing chrony testing wasting pellets