Im pretty sure the adapter is smooth bore for the 223 conversion. if it wasent you would have to have a exact match in rifleling to work right IMOO. im kicking around a conversion or a scratch built gun from spare parts. I want a 17 hmr as well. you can get 22lr to 223 chamber addapters for around $20. not sure how you would get it to feed and extract. I think on the ceiner set up the the addapter is sticking out of the barrel a ways. I have been looking for a cheap bolt source. a bolt action bolt could likely be modifed to fit in a custom carrier some how. Ive been tempted to just buy a wasr 22 and reverse engineer it and sell it when done. I want my conversion to use cheap mags possably rugger 10-22 or some other readly avaliable mag.