YOU SAID:

You've hit the nail on the head

INTO JAPANESE

頭に釘を打った

BACK INTO ENGLISH

I struck a nail on my head.

INTO JAPANESE

私は頭に釘を打った。

BACK INTO ENGLISH

I struck a nail in my head.

INTO JAPANESE

私は頭の中に釘を打った。

BACK INTO ENGLISH

I hit a nail in my head.

INTO JAPANESE

私は頭を釘で打った。

BACK INTO ENGLISH

I struck my head with a nail.

INTO JAPANESE

私は頭を釘で打った。

BACK INTO ENGLISH

I struck my head with a nail.