I am not intimately familiar with the model 16/116 series Savage rifles but it looks to me like the collar nut is an after market product, and maybe the wrench that was used to install it made the marks on the barrel. Whatever caused them doesn't matter from my perspective, as I don't consider Savage rifles to be eye candy anyway. I think their beauty lies in their accuracy, as every Savage bolt rifle I have seen in that was built in the last several years has been very accurate.