You gotta list your specific parts, brother. What receiver extension (buffer tube), what buffer, what buffer spring, etc.
Armalite AR-10 Carbine Receiver Extensions (buffer tubes) are longer than standard AR-15 carbine receiver extensions. That's a cause of a lot of hangup, right there, when just getting parts and assembling them. If it's not a collapsible stock setup, but a fixed stock setup, then there are other issues to figure out.
Post the specs/details on the parts used, and we'll go from there. <thumbsup>