What is on my muzzle?

[Buck1950]

A dime fall through with room to spare. Also noticed on the other pic that the vent rib ends right at the support, whereas mine has a slight nub.
Hard to see how this choke is effective considering the flare in it. Time to get some shells and test the pattern.

The advert says "Improved Cylinder" - maybe you could measure the id ? All those other choke tubes for diff sizes.

 

[groundrush]

The advert says "Improved Cylinder" - maybe you could measure the id ? All those other choke tubes for diff sizes.

The bore is 0.72". The smallest part of the choke is 0.82" and flares out to 1.05".
Doing some quick math, that would limit the extreme possible spread to 13.5' @ 40' (assuming the pellets fly absolutely straight after the choke). Would a cylinder bore have a spread that big?