it is marked
B MP 5.56 NATO 1/7
so I know it is a 1 and 7 twist and it is 20inch.
but who made it?
and what kind of accuracy are others getting from it.
so far for me it has been around moa out to 200 yards (all my range has).
I believe that was made by Bushmaster (I may be wrong).
that's a Bushmaster barrel with 556 Nato chamber.
as far as I knom all Bushmaster barrels are chrome lined other than SS ones.
my best group off the bench with my Colt (20inch, 1/7 twist, chrome lined) is 1.5-2inch at 100m using iron sight, factory ammo (american eagle & winchester) and stock trigger.
with some handloads, a decent trigger and a good scope I think you could easily achieve 1inch groups or less.