When I had the cylinder done the gunsmith brought all the throats up to one size as they varied a bit .410-411+. I hope I can find his info he was recommended by someone on this site but it been over 1-1/2 years ago however it was just the cylinder I sent to him the entire gun has not been checked out yet. The gun was purchased by my father inlaw in 1995 and I got it after he passed away so it isn't new just nearly unfired.