to protect himself

[artart]

Which are correct:

1) The gun was given to him to protect himself.
2) The gun was given to him to protect himself with.
3) The gun was given to him to protect himself with it.

4) They gave him the gun to protect himself.
5) They gave him the gun to protect himself with.
6) They gave him the gun to protect himself with it.

[do_shahbaz]

Which are correct:

1) The gun was given to him to protect himself.
2) The gun was given to him to protect himself with.
3) The gun was given to him to protect himself with it.

4) They gave him the gun to protect himself.
5) They gave him the gun to protect himself with.
6) They gave him the gun to protect himself with it.

Only 1) and 4), I reckon.

A user who is more versed in English syntax may be able to explain why.