The rifling was designed to spread the pellets. MF called it the "Supra" rifling. This is effective for woodcock shooting, but the most important application was cotton tail shooting.
Before the 50s, Europe was infested with cotton tails rabbits that could clean up an entire wheat field in no time. These creatures live in burroughs and are ferreted out with (you guessed it) a ferret. I have done it myself, and it's a lot of fun. However, the shooting distance is typically very short. If you use a full choke, you have rabbit marmalade.
Often, only one barrel was rifled.
In the 50s a doctor imported Myxomatosis to kill the rabbits in his park and managed to kill all the rabbits all the way to Russia. He was found guilty and sentenced to 1 FF of damage.
This is a shame as the rabbits are very tasty.
As for gun quality, the Robust is the poor man monoblocked gun, while the Ideal is the high end one.
Price wise, in 1930 the Robust ranges from 675 to 1800 FF, while the Ideal goes from 1200 to 15,000FF.
The Robust is very , you got it again, robust. Only the high end models have ejectors, and the retractable sling. They do last a long time and are capable of shooting 1000s of rabbits, partridges, hares, pigeons and even wild boar using slugs (for which the rifling was also useful)...
I do not know how new cartridges perform, but I imagine the shotcup can only reduce pellet deformation, and the resulting flyers.
Best regards,
WC
