When the barrel maker states that the finished length of a barrel will be 27" does this mean it will be 27" after threading and installing on the action, or will it get even shorter.
I believe it usually means it will finish to 27" including the threaded tenon in the reciever.If you want 27" from the end of the reciever to the muzzle,you'd need a 29" or there abouts barrel blank.Most barrel makers will make a mark or cut in the muzzle end of the blank where it should be cut to crown.
it means you have 27" of usible barrel to do with what you want. Longest possible will be a total barrel length of 27" which would include threads and all.
Most barrels will come from the manufacturer with a small cut at the muzzle letting you and your smith know where the quality barrel begins. There is generally an inch or so extra but this is belled out by hand lapping generally and can not be used unless you do not care about accuracy results /ubbthreads/images/graemlins/grin.gif!!