"IF" I am following this right then you have an enlarged area of about 1 3/4" followed by a 3/4" section back to bore size for the total length of 2". Sure sounds like a Jug Choke to me.
Most bulges I have seen which did not actually burst the barrel were nowhere near 1 3/4" long but were rather short.


Miller/TN
I Didn't Say Everything I Said, Yogi Berra