So my air soft pistol is a co2 pistol that shoots .177/4.5mm will this be allowed on field or no

No it would not most airsoft weaponry uses light plastic 6mm bbs while airguns use 4.5mm .177 bbs and it's not safe to shoot someone with a heavy metal bb

That sounds like an air pistol to me as pellet gun ammo is measured like regular lead ammo. Airsoft weapons involve plastic pellets usually measuring around 8mm in diameter while air pistols involve lead pellets usually measuring as .177. I hope my answer helps you.