It is not permissible to use animals for target practice
Question

                I killed a Rabbit by shooting it for the purpose of practicing my aim. I buried it afterward. I deeply regret what I did. What is the Islamic Ruling on that?
Praise be to Allah. 
          Undoubtedly this action that you did is something which 
          is forbidden according to sharee’ah and is not permitted. This is a 
          form of tormenting animals which the Prophet 
          
          (peace and blessings of Allaah be upon him) forbade. 
 
          1.It was narrated in the 
          hadeeth from ‘Abd-Allaah ibn ‘Umar that the Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) said: “A woman was punished 
          for a cat which she imprisoned until it died, and she entered Hell because 
          of that. She did not feed it or give it water when she imprisoned it, 
          and she did not leave it free to eat of the vermin of the earth.” (Narrated 
          by al-Bukhaari, 2236; Muslim, 2242). Al-Nawawi said: the apparent meaning 
          of the hadeeth is that she went to Hell only because of this sin.
 
          2.It was narrated from Ibn 
          ‘Umar (may Allaah be pleased with him) that he entered upon Yahyaa ibn 
          Sa’eed and one of Yahyaa’s sons had tied up a hen and was shooting at 
          it. Ibn ‘Umar walked over to him and untied it, then he brought it and 
          the boy and said, “Do not allow your boys to tie up birds in order to 
          kill them, for I heard the Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) forbidding the tying up 
          of animals or other creatures in order to kill them.”
 
          (Narrated by al-Bukhaari, 5195; Muslim, 1958. The version 
          narrated by Muslim says, “The Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) cursed those who do that.”)
 
          3.It says in another hadeeth 
          which was narrated from Ibn ‘Abbaas that the Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) said: “Do not use anything 
          in which there is a soul as a target.” (Narrated by Muslim, 1957).
 
          Al-Nawawi said: 
 
          The Messenger of Allaah 
          
          (peace and blessings of Allaah be upon him) forbade detaining or tying 
          up animals (for the purpose of killing them); according to another report, 
          ‘Do not take anything in which there is a soul as a target.’ The scholars 
          said that tying up animals means restraining them whilst they are still 
          alive in order to use them as targets and so on. The words ‘Do not take 
          anything in which there is a soul as a target’ means do not use living 
          animals as targets for shooting as targets made of leather and so on 
          are used. This prohibition means that doing this is haraam. Hence the 
          Prophet 
          
          (peace and blessings of Allaah be upon him) said, according to the report 
          narrated by Ibn ‘Umar which follows this report: “Allaah cursed the 
          one who does that.” And because it is torturing animals, a waste of 
          their [animals’] lives, a waste of money, causing the animal to die 
          without slaughtering it in the proper Islamic manner if it is an animal 
          whose meat may be eaten, and wasting an animal from which benefit may 
          be derived in other ways if it is an animal whose meat may not be eaten. 
 
          Sharh Muslim, 13/108 
 
          You must repent sincerely to Allaah from this deed and 
          seek His forgiveness, and do lots of good deeds so that Allaah will 
          forgive your sin. 
And Allaah is the Guide to the straight 
          path.