I have a 16 gauge H Grade Lefever with 28" "London Twist" barrels. It is post 1907 as it carries the 1907 patent date on it. Both barrels are full choke so un-cut. Amazing thing is it has 3" chambers by actual measurement.
After discovering this length chamber my first thought was WHY would anyone rechamber a 16 to 3". My 2nd thought after thinking about it a bit was it was far more likely to have been "Ordered" this way when new, t5han to have been rechambered. In spite of being built on the XX frame it has rather heavy barrels & weighs in @ 6 3/4 lbs. As 3" hulls were available to order when this gun was new it was likely ordered this way to give a better wad column with the full ounce load which was commonly the max shot weight for a 16 of that era for use as a waterfowl gun, thus the two full chokes.
The main difference I can see on this XX frame is it has a slightly narrower bar than my non XX frame Lefevers. This gives it a good proportion with the 16ga barrels. It handles very well & would be much more useful for me if not so tightly choked, but I do not want to destroy it's originality by opening them.