I've shot lots of the big 3's swaged lead bullet .38 ammo over the years and have not noticed a leading problem with any of them. The Remington .38 +P LSWC-HP load was my favorite and also is my preferred .38 service load. I was taught by Allen Jones, firearms examiner for the Dallas County Forensic lab and later all the way to a VP position at Speer, that the Remington load was dry lubed and semi-hollow based which allowed it to upset properly in the cylinder throats and seal gas. Pulled examples confirmed that.
Where you get bad leading is from lead bullets that are undersized for the cylinder throats and that fail to fully upset in those throats, leading to gas blow by that melts lead off the base and heel area and deposits it in the forcing cone and bore. You don't size bullets to the bore but to the throats. Old BS information that needs to die on bore sizing. Also, and this is big, lots of cylinder throats are undersized (or oversized) and poor bullet upset, improper dimension bullets, etc. lead to bore leading or bad accuracy. Throats can be uniformed to fix the undersized ones and there's a guy on Cast Boolit Forum that goes by DougGuy who does all kinds of cylinder remediation as a business. He gets rave reviews.
Hope this is of some value to you.