I am not a gunsmith but, I always thought the dimples should be placed on the sight. If I made some kind of error, the sight would be easier to replace than the barrel/slide.
To remove the lead vapor accumulation on the cylinder I just use a few drops of any bore cleaner with a bronze "toothbrush". It's quick and easy to do as a normal part of after shooting gun care.
No soaking or using abrasive products are involved.
Another thing to check is the hammer nose bushing.
If it is inset in the frame, that will allow the primer to stay backed out of the case when the cartridge is fired. Check it with a straight edge across the frame to be sure it is flush.
I experienced this problem once. The average "street...