I assume that gun was designed for target shooting . When the porting nonsense started , about the time sporting clays became popular, we did some serious tests.
I understood all the physics involved so I knew the outcome. But some who didn't had to be shown. A very experienced and good shooter went through a round of SCs .At each stage firing half the rounds with a ported gun and half with an unported gun .Both were Brownings , identical except for the porting.
The shooter could not feel any difference and none of us could see any difference.
The point is that the shotguns use fast burning powder so ignition is complete before the shot string passes the ports .There is little hot gas exiting the ports .Therefore no reduction in recoil.
This of course is with TARGET loads. Hotter hunting loads will see a recoil reduction since there will be hot expanding gases at the ports. BTW the longer the barrel the less the benefit.
The porting fad is another fine example of the love of gadgets by Americans and their lack of knowledge of science. Learn the science of it and you won't be so quick to buy an ugly barrel with holes .