The old style (pre mag) receivers were angled front and back at the loading port to allow room for the fingers when loading pellets. There was also a groove that you could lay the pellet into that the bolt rode in. There's not a lot of "meat" in the new style receiver to allow for much reshaping without going through and making a hole to the inside.
Or just hold the pellet with long tweazers like some guys do when shooting side or under lever springers. lol