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Here is an older, longer version. I would not classify it as a private devotion. It is a prayer for protection of the individual and the Church, and most appropriate for Mass.

PRAYER TO SAINT MICHAEL THE ARCHANGEL

Most glorious Prince of the Heavenly Armies, Saint Michael the Archangel, defend us in "our battle against principalities and powers, against the rulers of this world of darkness, against the spirits of wickedness in the high places" (Ephes.,VI, 12). Come to the assistance of men whom God has created to His likeness and whom He has redeemed at a great price from the tyranny of the devil. Holy Church venerates thee as her guardian and protector; to thee, the Lord has entrusted the souls of the redeemed to be led into heaven. Pray therefore the God of Peace to crush Satan beneath our feet, that he may no longer retain men captive and do injury to the Church. Offer our prayers to the Most High, that without delay they may draw His mercy down upon us; take hold of "the dragon, the old serpent, which is the devil and Satan," bind him and cast him into the bottomless pit "so that he may no longer seduce the nations." (Apoc. XX, 2).

Here's the unabbreviated Prayer to St. Michael composed by Pope Leo XIII:

O Glorious Archangel St. Michael, Prince of the heavenly host, be our defense in the terrible warfare which we carry on against principalities and Powers, against the rulers of this world of darkness, spirits of evil. Come to the aid of man, whom God created immortal, made in His own image and likeness, and redeemed at a great price from the tyranny of the devil.

Fight this day the battle of the Lord, together with the holy angels, as already thou hast fought the leader of the proud angels, Lucifer, and his apostate host, who were powerless to resist Thee, nor was there place for them any longer in heaven. That cruel, that ancient serpent, who is called the devil or Satan, who seduces the whole world, was cast into the abyss with his angels. Behold, this primeval enemy and slayer of men has taken courage. Transformed into an angel of light, he wanders about with all the multitude of wicked spirits, invading the earth in order to blot out the name of God and of His Christ, to seize upon, slay and cast into eternal perdition souls destined for the crown of eternal glory. This wicked dragon pours out, as a most impure flood, the venom of his malice on men, of his depraved mind, corrupt heart, spirit of lying, impiety, blasphemy, his pestilent breath of impurity, and of every vice and iniquity. These most crafty enemies have filled and inebriated with gall and bitterness the Church, the Spouse of the Immaculate Lamb, and have laid impious hands on her most sacred possessions. In the Holy Place itself, where has been set up the See of the most holy Peter and the Chair of Truth for the light of the world, they have raised the throne of their abominable impiety, with the iniquitous design that when the Pastor has been struck, the sheep may be scattered.

Arise then, O invincible Prince, bring help against the attacks of the lost spirits to the people of God, and give them the victory. They venerate Thee as their protector and patron; in Thee Holy Church glories as her defense against the malicious power of hell; to Thee has God entrusted the souls of men to be established in heavenly beatitude. Oh, pray to the God of peace that He may put Satan under our feet, so far conquered that he may no longer be able to hold men in captivity and harm the Church. Offer our prayers in the sight of the Most High, so that they may quickly conciliate the mercies of the Lord; and beating down the dragon, the ancient serpent who is the devil and Satan, do Thou again make him captive in the abyss, that he may no longer seduce the nations. Amen