XM177 was an 10.3” or so barrel with a 6” sound moderator. Of course the clones were just a short barrel with a long flash hider welded on to keep it legal. Dumbest thing I ever saw.
So whats the fascination with XM177 reproductions lately?
It was the first 'shorty' AR that was around and, I suppose, lead to the M4. Fifty years ago it was a fascinating piece and if there is a current interest it likely mirrors the historical interest in the original M-16's and A1's.