You can get special chamber reamers that will give a tight leade, but they are made for one bullet shape. If you decide to use another brand of ammo or another bullet, the round might not fit. I would stick to the SAAMI specs, which are built into the standard reamers.
But distinguish between a tight leade (where the bullet fits) and a tight chamber neck (where the neck of the case fits). If the chamber neck is too tight, the case neck can't expand to release the bullet and pressures go quite high.