Porting WILL reduce muzzle jump in shotguns, and porting WILL decrease felt recoil.
In the 80's and 90's I was shooting Trap and Skeet competition. I was shooting 10,000+ shotshells per year for most of those 20 years.
Both my single barrel Trap gun, a Browning BT-99, and my Trap doubles and Skeet gun, a Browning Citori, came from the factory with solid, unported barrels. I had the BT-99 Angle ported and the Citori Pro-ported. When I had them ported, there DEFINITELY WAS a noticeable reduction in felt recoil and in muzzle jump.
There is also a noticeable reduction in felt recoil with the Angle ported BT-99 over the Pro-ported Citori shooting the same shells, even though the Citori is a heavier gun which should absorb some of the recoil.
The ports in shotgun barrels are in front of the chokes. Therefore if the ports did affect the wad, that would all be changed when the wad passes through the choke. Also, for this discussion, I shot two 12 ga target shells, from the same box, into the air and recovered the wads. One shell was shot from my Pro-ported Citori with a Skeet choke. The other shell was shot from my un-ported Rem 870 that also had a Skeet choke. I cannot see any visible difference in the wads, even when I examined them under my 3x magnifier light.
As for porting increasing muzzle noise, I just don't see (or hear) that happening.
In the 200,000+ rounds of Trap and Skeet that I have shot (and still shoot +/- 100 shells every Wednesday evening) I cannot tell by the muzzle noise if a gun is ported or not. I have to look at the muzzle and see if the barrel(s) are ported.
HOWEVER, every fall just before bird seasons (like now) we get many shooters who haven't shot their shotguns since the end of last bird season, and want to shoot a box or two before going hunting. I have never seen any of shooters with a ported field gun, but you can instantly tell when one of these shooters shoots his field loads. They are VERY NOTICEABLY LOUDER than standard target shells, even if the target shells are shot in a ported barrel.
