One way to look at is that all modern Amils are partial preterist, but not all partial preterists are modern amil.
The term Amil literally means "no millennium", however to be considered Amil by today's standards, one must believe the "1,000" years is symbolic for the time period between Christ 1st advent and his future 2nd coming. The belief of this symbolic "1,000" for time between the 1st and 2nd advent is partially based on statements made by Augustine in his work "city of god". Most amil early church fathers are silent on their belief of the 1,000 years symbolized.
As a partial preterist, I don't believe in a literal millennium like Amils, however, I don't believe that the millennium is symbolic for the time between the 1st advent and 2nd coming, and thus wouldn't be considered Amil by modern standards.
I don't believe the 1,000 years is symbolic for the time between the 1st and 2nd advent because according to revelation, the 1,000 years doesn't end at Christ coming. When the 1,000 years are completed, satan is loosed.
Revelation 20:7 And when the thousand years are ended, Satan will be released from his prison.
And while revelation does say "after the 1,000 years" the dead come to life, it isn't until after the 1,000 years AND after satan's little season that the dead come to life to be judged.
Revelation 20:11-15 Then I saw a great white throne and him who was seated on it. From his presence earth and sky fled away, and no place was found for them.
12And I saw the dead, great and small, standing before the throne, and books were opened. Then another book was opened, which is the book of life. And the dead were judged by what was written in the books, according to what they had done
Thus the timeline of the parabolic language of revelation 20 has: 1.) the completion of the 1,000 years, followed by 2.) satan loosed for a little season, followed by 3.) the great white throne judgment and resurrection of the dead. And this doesn't add up with the traditional teachings of Amil.
My belief is that the 1,000 years is symbolic for the restoration of the Davidic throne through Christ's 1st advent (ministry, death, ressurection, ascension, and sending of the Spirit).
The results of this "1000 years" are:
1.) Satan is bound by Christ's 1st advent:
Revelation 20:2 And he seized the dragon, that ancient serpent, who is the devil and Satan, and bound him for a thousand years,
Matthew 12:29 Or how can someone enter a strong man’s house and plunder his goods, unless he first binds the strong man? Then indeed he may plunder his house
Luke 11:21-22 When a strong man, fully armed, guards his own palace, his goods are safe; but when one stronger than he attacks him and overcomes him, he takes away his armor in which he trusted and divides his spoil
2.) Satan is cast out by Christ's 1st advent:
Revelation 20:3 and threw him into the pit, and shut it and sealed it over him, so that he might not deceive the nations any longer
John 12:31-33 Now is the judgment of this world; now will the ruler of this world be cast out. And I, when I am lifted up from the earth, will draw all people to myself.” He said this to show by what kind of death he was going to die.
Revelation 12:7 Now war arose in heaven, Michael and his angels fighting against the dragon. And the dragon and his angels fought back, but he was defeated, and there was no longer any place for them in heaven.
3.) The 1st resurrection is Christ being raised from the dead at his 1st advent, which results in those in Christ being born again and a kingdom of priests
Revelation 20:4-6 Then I saw thrones, and seated on them were those to whom the authority to judge was committed. Also I saw the souls of those who had been beheaded for the testimony of Jesus and for the word of God, and those who had not worshiped the beast or its image and had not received its mark on their foreheads or their hands. They came to life and reigned with Christ for a thousand years. The rest of the dead did not come to life until the thousand years were ended. This is the first resurrection. Blessed and holy is the one who shares in the first resurrection! Over such the second death has no power, but they will be priests of God and of Christ, and they will reign with him for a thousand years.
Ephesians 2:4-7 But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved— and raised us up with him and seated us with him in the heavenly places in Christ Jesus, so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus
1 Peter 2:9 But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light.
4.) Upon on the completion of this "1,000" symbolic years Satan is released to have a "little season"
Revelation 20:3 until the thousand years were ended. After that he must be released for a little while.
Revelation 20:7 And when the thousand years are ended, Satan will be released from his prison
John 14:30 I will no longer talk much with you, for the ruler of this world is coming. He has no claim on me,
Revelation 12:12 Therefore, rejoice, O heavens and you who dwell in them! But woe to you, O earth and sea, for the devil has come down to you in great wrath, because he knows that his time is short!”
Romans 16:20 The God of peace will soon crush Satan under your feet. The grace of our Lord Jesus Christ be with you.
I would argue the 1,000 years are derived from the time period between David and Christ. This is inspired by Steve Hahn who wrote in his book The Ignatius Catholic Study Bible: The New Testament "The background of the millennium may be traced to the period of the Davidic Covenant, which was established almost exactly 1,000 years before the coming of Christ."
Thus the Davidic covenant was fulfilled at Christ's 1st advent, 1000 years after the promise was given to David.
Luke 1:32-33 He will be great and will be called the Son of the Most High. And the Lord God will give to him the throne of his father David, and he will reign over the house of Jacob forever, and of his kingdom there will be no end.”
Acts 2:30-31 Being therefore a prophet, and knowing that God had sworn with an oath to him that he would set one of his descendants on his throne, he foresaw and spoke about the resurrection of the Christ, that he was not abandoned to Hades, nor did his flesh see corruption.
Acts 15:15-16 And with this the words of the prophets agree, just as it is written, “‘After this I will return, and I will rebuild the tent of David that has fallen; I will rebuild its ruins, and I will restore it,
And the results of the fulfillment are listed in points 1-4 above and testified by the Gospels and Epistles.