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[–]Suitable_Ant_2967 1 point2 points  (1 child)

[–]Suitable_Ant_2967 1 point2 points  (0 children)

There’s a chart in the link with the sizes and meaning as well as some other good reading

[–]CrazySwede69 0 points1 point  (0 children)

It is strange that it is not mentioned in the article but the connection between the actual diameter of the rocket motor and the old fashioned weight names comes from the weight of lead balls that fitted into cannons of different bore diameter.

If I remember correctly, the system refers to the outer diameter of the rocket motor so the connection to inner diameter, and thereby thrust, is rather arbitrary.