Ebay has some good chisels of all types up for sale. The older Buck Brothers and some of the other english makes are good. Stockmakers usually modify or make their own special purpose chisels. The dog leg chisels used to get in really tight spaces and scrapers used in the barrel channels. You have to be fearless enough to take a good chisel and make it into something that will really do what is needed. Jerry Fisher used to sell some special purpose chisels or maybe they were scrapers. SDH would have a good handle on what is needed.I have about 200 that I have collected over the years and some were from gunsmiths that had modified them in novel and job specific ways.