Just as Kiwi block indicates - All bullets, regardless of that any manual says is the overall length, must be seated to THAT bullets PROPER and REAL bullet overall length so that it isn't jammed into the lands.

In comparrison to the Hornady 160gr.RN 6.5mm bullet, the Sierra 160gr. had very long full diameter sides and must be seated VERY deeply in comparrison.

To properly handload your own ammo, you MUST know how to find the proper OAL for YOUR rifle.

Another bullet with very long straight sides (short ogive), it the .375" 300gr. Norma RN. it must be seated very deeply inside the case.

If I had a 6.5 that measured .268" groove to groove, I'd have no problem quickly deciding to use the Hornady Carcano bullet.