[Drakker]

Some claim that the BB already rides the ceiling of the barrel because of the hop-up. I ran some coated barrels for years, a TK Twists on my GBB 1911 and a Madbull in a few different AEGs and both had lost a lot of coating on their ceilings and little at the bottom... so from this anecdotal evidence, the BB might already do that anyway.

My take on it is that with the back spin hop-up, when the BB hits the bottom, it is kicked up, and when it hits the ceiling, since it's back spinning, it either rides a bit, or it bounces less because of the direction of the spin, so it would tend to hit the ceiling a lot more often, chipping at the finish. But that's just guesswork, and it would probably hit the ceiling even more on an LRB, so what you say might be right.