Originally Posted by White Oak 06

Does it matter with ogive shapes when adjusting for seating depths ?
For cartridges held in magazines, the COAL (Cartridge Over All Length) must be shorter than the inside if the magazine.
The accuracy of many bullets is affected by how far the bullet travels before engaging the rifling. This distance can change with different ogive shapes.

Do reloading manuals cover this topic ?
Some may, I have not seen it, but I haven't read all manuals.

When you buy new cases , do they have to be trimmed to length ?
Generally not, but it doesn't hurt to do it.

I see that some casings are crimped to the bullets and some are not , why is this ?
Cartridges for guns with tubular magazines should have their bullets crimped so that the cartridges in front don't push the bullets back into their cases, especially under recoil.
Cartridges with heavy bullets, and with heavy recoil should be crimped to prevent the recoil from pulling the other bullets in the magazine or cylinder.
With proper case sizing, the neck tension usually holds most bullets in place.

Thank you !