Well my Old Model Vaquero in .45 colt use to have a line on the cylinder too.
After I fixed the timing and polished out the cylinder, no more bolt drag marks on mine and the bolt drops right into the cylinder lock lead where it should.
I also sanded out the warning on the barrel, she's sports some beautiful bookmatched curly walnut colt style grips, clements bullet ejector rod, heavy duty spring latch and an belt moutain cylinder pin, also put a BP chamfer on the cylinder, throats have been properly sized and I installed a super blackhawk hammer but reshaped the width of the thumb cocker, installed a trigger stop. It was also sent to Lee's gunsmith and had some work done to it to slick it up some.
I love it now that it's had a little work done to it!
Not all the above modifications are shown but are completed.