Quote Originally Posted by Claven2 View Post
It's not linear. virtually all 1941 LB's had grooved HG's. In 1942, some subcontractors began making them smooth, while others made them grooved. On any LB made 1942 or later, you can have either type HG. Same goes for the other makers.

The assemblers just used whichever HG was next in the bin. I find the grooved HG's look better though.
Thanks Claven. I agree, the grooved ones are quite beautiful...so it could go either way for most of the war production? Thus putting a grooved HG on any LB 41-45 wouldn't be wrong?