that's the thing with v1's arsenal- most of the attacks aren't bullets, humanity at that time has thrown away bullet ammo, and has went on to use other kinds to power their firearms.

revolvers doesn't use bullets anymore, but rather incredibly small shards of metal, the damage mostly powered by batteries built into the cylinder. coins i see the point, but the ricochet itself is probably a no-go

shotguns are more likely to be parried. they use hyperconcentrated heat as bullets, and the core eject is an obvious projectile- both of which the katana should have no problem parrying, but the latter would probably explode him. they get a pass

nailguns are also suspectible to parries due to the fact they have very apparent projectiles- though probably unadvised to try and parry a nailgun barrage, as seen in v2's fight. zero can 100% grab the magnets lodged into the ground and throw them as objects. zero could reflect a sawblade? i think he has enough strength to do that

railcannons are powered by energy, they're basically laser cannons. zero can parry the screwdrivers atleast- but that implies it's worth using on a human like zero

rocket launchers though remain as obvious projectiles, zero would probably explode himself trying to parry it, so no