Using an extractor groove for headspacing sounds kinda iffy. Round detent balls do not hold very tightly. This is just one reason why most straight walled cartridges headspace on the mouth (like 45 ACP). If you used an angular anvil-shaped extractor to hold the cartridge, it would have to be fairly heavy to withstand the force of the discharge.
Bullets straight with the case neck like 22 LR are called heeled bullets. In the late 1800s, many cartridges had heeled bullets. Mostly they either switched them to internally lubricated or they disappeared. Heeled bullets are a terrible way to insert bullets in a case. It deforms the bullets as the crimp is rolled into the case, affecting accuracy. You are stuck with externally lubricated bullets.