Order number DT-770550, I do not recommend buying ar10 308 build kits from here. They gave me AR-15 parts which were obviously not for a 308 ar10. When I contacted customer service they said it was too far outside the warranty. I bought it and it sat for a couple months since I was buying parts over time. When I began building it was when I ran into these issues and contacted them which was no help because it was already past the warranty date. When I built it after buying the correct parts the barrel was seated in the receiver and there is an obvious edge where the bullet and cartridge would scrape and create a malfunction. Since learning this issue I had to grind and polish the barrel where the bullet gets fed. Then I discovered another issue, the gas tube they sent me was too short..so now I am waiting for a new gas tube.