yes it will degrease hole dia and we used shot peening to decrease a dia was oversize
so it will be smaller simply cause u denting the surface and there is a material pumped out from the surface and thats looks like a peaks but if u use any polishing after, u will go back to your intial dia.
also if your nozzle is not straight u will have ovality problem and you will be confused if the dia is samller or bigger actually it is oval
please note that always check your material kind and thickness and intensity goes with that
