I tried the Remington Mag Tube Extension on the H&R Excel Auto 5 shogun and it does fit. The TacStar tube I tried will not screw all the way down because there is not enough thread space on the TS tube. It likes about 1/8". I didn't have a Choate Tube to try, it might have more thread space. A spacer can be made out of a 1" ID washer to fill the gap and the TS tube will work. If it fit the H&R Excel it should work on the Verona 405 also.
GC