Your going to have to buy an aftermarket choke to get that constriction, if it's the shotgun that rings your chimes get it, measure it and order what you need.
The shotgun you listed comes with C, IC, and M the mod is more than likely around .020 constriction
The M-3000 Model 31832 also has a synthetic stock 24" barrel and come with a IC, M, and XFT(extra full turkey) with a diameter of .661 so you would be close the .060 constriction and it is $140. less.
The chokes supplied are from Stoeger catalog, the choke constriction is from a review on a choke retailers sight'
A call to Stoeger tech should answer your questions.
Standard for 12ga is .729 bore diameter but they do vary a little. I have old shotguns that are as small as .710(from the last century) and as large as .735(I think it was honed) most run close to .729 I have a Skeet's micrometer bore gauge that measures the bore 12" from the muzzle or breech.