Hard cast , no worries , to check look at the start of the rifling, in the grooves, also at the muzzle end. It will in most cases exist in patches, easy to see , a matte stainless looking streak.
Also look in the cylinder just behind that ring in the foward part where the chambers narrow. Sometimes lead will build there and form a ramp.
bronze brush will dis lodge the lead , and some solvent will help also.
Where problems crop up is when the lead is allowed to sit , and build with each visit to the range. So get it out , and no rust will form under the lead , which would happen if left there. Hope this helps, someone else will visit , and have more info on this, or perhaps help to clarify my poor writing skills.

You can tell when you look into a clean barrel , and see nice sharp squared off rifling .