41So those who accepted his message were baptized, and that day about 3,000 people were added to them.
so i'm reading that they were baptized, not sure how you are getting to "they were saved" myself. They were "added to them," which is not the same thing imo.
Acts 2
37 Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, "Brethren, what shall we do?"
38 And Peter said to them, "Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit.
39 For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him."
40 And he testified with many other words and exhorted them, saying, "Save yourselves from this crooked generation."
41 So those who received his word were baptized, and there were added that day about three thousand souls.
Peter tells them that if they get baptised their sins will be forgiven (vs 38); they will receive the Holy Spirit (vs 39); they will be saved from this crooked generation (vs 40).
They were added to the Church.
That's salvation.