Years ago I made a slug barrel for one my shotguns, by shortening an older barrel and removing the ventilated rib. In order to soldier sights to the barrel you will need steel sights. At the time I did my project Remington rifle sights were the only ones all steel. I forget where I got them but Western gun parts would be a good place to try. Or any established gun smithing shop should have a set kicking around. Such as Epps. I soldiered them on using 50/50 plain old soldier. The trick is having the proper flux. Which a friend of mine had at his welding shop. I just leveled the barrel in a vise, eye balled the alignment for the sights, marked the positions. Tinned the front and rear sights where they would contact the barrel. Note I did this when the barrel was in the white. I blued the barrel after the sights were installed. The sights I installed have been on for about 30 years without issue, and there have been a lot of rounds down the barrel. Hope this helps some