[Spktyr]

The microcracks are in the solid rocket motor itself, not the casings.

https://www.sciencedirect.com/science/article/abs/pii/0026080075900130

https://aip.scitation.org/doi/abs/10.1063/1.50642?journalCode=apc

https://www.researchgate.net/publication/245435804_Fracture_Mechanics_of_Composite_Solid_Rocket_Propellant_Grains_Material_Testing

Try reading about the aging of solid rocket motors and the effects of microcracks on the burn rate and consistency of same.

[dila813]

Cause and effect, think about it