Tim, you said you measured the chokes with a choke gauge. Did you use a wedge shaped "pocket gauge" or a micrometer type gauge?

And if you did use a mike what were the actual constrictions, from bore diameter?

There are different ideas about what constriction constitutes a given choke designation, such as Improved Modified. I like the chart that is on Hallowell's site, which shows Improved Modified in a 12 bore to be .024" to .031". Is yours that tight?

May God bless America and those who defend her.