[Clint Boyer]

I've mounted a few scopes myself, never have done any lapping. I've heard of the process before but have never seen any need for it.
I, myself, wouldn't buy any rings didn't appear to be machined properly. I guess there is always a chance that an unseen defect or irregularity might slip by. But whose to say that a lapping job is done right? If it's required to keep the warranty in force then it may be a good idea. I'd say some jewelers rouge and that alignment bar should do the trick.