From the KJV:
8 Now when He had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each having a harp, and golden bowls full of incense, which are the prayers of the saints. 9 And they sang a new song, saying:
“You are worthy to take the scroll,
And to open its seals;
For You were slain,
And have redeemed us to God by Your blood
Out of every tribe and tongue and people and nation,
10 And have made [d]us kings[e] and priests to our God;
And [f]we shall reign on the earth.”
Now notice the phrases with "us" in the RSV
“Worthy art thou to take the scroll and to open its seals,
for thou wast slain and by thy blood didst ransom men for God
from every tribe and tongue and people and nation,
10 and hast made them a kingdom and priests to our God,
and they shall reign on earth.”
Which of these is probably most accurate to the original? Before you answer, notice that in the KJV, The 4 living creatures are included in the "us." That really does not make sense.
In the making of the Received Text (Textus Receptus), Erasmus had only one text to work from for the Book of Revelation, and it was not a Byzantine text as all the rest of the New Testament was. He had many Byzantine texts for the rest of the New Testament. It would seem then that at least for the book of Revelation, perhaps the KJV is not the most accurate text.