Hey NWFA. So I just finished up a couple of my 80% lowers and it's now time to start the build. This is my first time owning a AR sport rifle and my problem is I can't seem to find a buttstock that's long enough for my long arms. Every AR I pick up to shoot I feel I need a few more inches in length on the extendable buttstock. Online no one states the dimensions of the buttstock .What's my options ? Commerical or Mil spec ? Thanks guys.