You did not specify which Bolt carrier group you purchased.
If it was the A.R. 15 platform Bolt carrier group it has 1 extractor spring and 1 O-ring(buffer) installed
The 308 Bolt carrier group have 1 outer extractor spring, 1 inner extractor spring and one O- ring(Buffer)
It should be noted :The ArmaLite rifle (AR 10) is not compatible with the DPMS gen 1, LR 308,SR 25