Parker chokes...

[OH Osthaus]

Some one with the book handy (my copy is not) maybe able to confirm the barrel length

But 30 is pretty common

[James L. Martin]

57109 not listed in the book

[C.O.B.]

I have a DHE 20 thats choked cyl in the right barrel and IC in the left a deadly Grouse set up and CHE & DH 16's that letter Cyl & Full. The CHE has 28 inch barrels while the DH has 26.