i know i picked the wrong time to buy,but i got one.it is a colt mt6400 not exactly what i wanted but i couldnt find the 6920 this one came in and i took it.my question is when i can find a milspec buffer tube for a collapsable stock can i reuse my spring and buffer or do i need a different one.(my stock looks adj but is pinned.)i called colt and they did tell me the gun was milspec.sorry if this is a dumb ? but trying to learn.thanks Wanna kill these ads? We can help!