Well I did eventually get round to using my smoothbore .25 heavy Gem to test the theory out. The doughnut type of spread pattern is only a problem with the wadded shot technique, as when the shot is contained in a ‘cartridge’ casing or embedded in chalk, you do not seem to see it.

So I used the wadding method with my Gem and packed about 16-17 of the small shot into the barrel, sandwiched between a loose fitting wad of tissue at the front and a tight fitting wad at the rear. I then recorded the spread pattern at a distance of 16 feet from the target. Here is a typical result, alongside a typical result, also at a range of 16 feet, obtained with my rifled .22 Webley Mk.3, charged with shot in exactly the same way.




So it is clear that rifling definitely causes a doughnut type of spread pattern, whereas with a smoothbore the shot spread is more uniform and concentrated over the point of aim. Interestingly the maximum spread of both patterns is about the same.