A: Your concern is a valid one. While the shot capsule protects the bore nicely, there have been reports of bore leading due to shot. Conventional cleaning is typically adequate for the sporadic use of shotshells. Keep in mind though, that extended shooting may result in severe bore leading that would require heroic measures, such as the Lewis Lead Remover (brownells.com). Other than that, I see no cause for concern.
Rifleman Q & A: Leads On Leading
Q: I would like advice concerning the use of “shotshells” in pistols. I typically carry a revolver when clearing brush on my 35 acres due to encounters with snakes. In my six-shooter I feel more secure carrying CCI .38 Spl. shotshells loaded with approximately 135 pellets of No. 9 shot. Though the lead shot is encased in transparent blue plastic, are there concerns with barrel leading? I have not yet experienced performance issues, but will continued use of pistol-caliber shotshells affect the gun, more specifically, the barrel’s rifling?