Do rifled choke tubes improve slug accuracy?

By Jason Wimbiscus

12 gauge rifled tube from Carlson’s Choke Tubes. (Photo: Jason Wimbiscus)
Of the many technological developments intended to improve the accuracy potential of shotgun slugs (and also one of the most summarily dismissed) is the rifled choke tube. After all, claim the device’s critics, how could a few inches of shallow rifling at the end of a smooth barrel do anything to tighten slug groups? Further, won’t the fact that that the slug is engaging the rifling only after reaching near-peak velocity actually be detrimental to accuracy?
Obviously, such theoretical problems with rifled choke tubes must not be as big an issue as the detractors claim. If they were, rifled tubes probably wouldn’t sell well enough for major firearms and accessory manufacturers to justify their continued production.  However, since I’m not one to judge a product based solely on anecdotal evidence, I obtained a rifled choke tube of my own and took it to the range with an assortment of shotgun slugs to see for myself what, if any, effect the addition of a rifled tube would have on slug groups.
The tube
The Carlson’s rifled choke tube installed in the muzzle of the Baikal MP 94. (Photo: Jason Wimbiscus)
The 12-gauge rifled tube I

Source: Guns.com