Is there diffence pattern size (diameter ) between 12 ga Tight-Standart-Overbore barrels on 12 ga and equally choke construction.
In theory the tighter the bore, the longer the shot column. The longer the shot column the more setback. Setback is the deformation of the pellets at the rear of the shot column caused by the weight of the pellets at the front when being accelerated by the powder ignition. Setback causes distorted pellets. Distorted pellets tend to open the pattern.
In practice, the difference is so slight that I don’t think that it makes a meaningful difference. But it is a good question.
Shotgun Report’s Technoid