My S&W M&P9 barrel has these strange lines across the rifling at the ramp end. Round count about 2,000 with standard load Winchester and UMC ball ammo. Still accurate and functioning 100%. The "fanning" you see deeper in the barrel is artifact of the digital image. Does anyone have an idea about what is going on here?
See the attached pictures. Thanks for your consideration, Mark

Those marks are from the button rifling process when the barrel was manufactured.

I’ve had barrels like this. It’s gross, unacceptable, but most of the time they shoot tremendous but it’s another way too common thing for us to end up w. I had a marlin 45-70 w this, a 300 blackout barrel from a manufacture from Texas who’s barrel was like this, and a 2 barrels from delta team tactical (large bore calibers) like this. All guns shot great but it’s crazy.