front sights
As noted, many P220's do have dovetailed front (and rear) sights. I cannot advise if any or all of the BDA versions were made in such a fashion, but all the SIG marketed P220's ( and other P series) that I had dealings with from (about 1990) as agency firearms, several dozen of them, had both front and rear sights that could be removed via a dovetail, and SIG sold a very high quality sight tool for that purpose. There were actually two versions of that tool, if I recall correctly, or at least I had two versions in my armorers box. One fit the stamped slide versions, and the other fit the later milled slide models. Much the pity, I had to give them back when I retired.
Moving, or removing the front sight could be desirable for several reasons. SIG sold numbers those pistols with tritium based night sights, and it was not uncommon in duty use to have one of those tritium sights go bad and the front sight "lamp" no longer function. Occasionally, a pistol would be issued at the academy and NOT have night sights, and the recipient would desire same,and the task would fall onto the park level armorer. SIG also sold both front and rear sights in different heights. Very occasionally, a P220 (or other P model for that matter) would not shoot to point of aim and have an elevation issue. Fine tuning the rear and sometimes front sights with different sight heights could allow an exact zero to be obtained. The P series came with certain sight heights as standard. If one examines the factory sights on their P- SIG closely, a sight number is usually visible on both front and rear units. I'll add that for a windage adjustment on the rear sight, the tool allows for precise and incremental movement, not the pound and guess process of using a hammer and punch.
I would caution that moving the front sight on a P-series can indeed be tricky. Though the tool took them off easily enough, care had to be taken to start the sight back in its dovetail aligned precisely. The base on the front sight is VERY thin, and if bound in any fashion as it is moved, the post itself can can shear from the base. If that happens, the Chief Ranger will not be happy with you, as those tritium night sights are expensive.