It's like having a beautiful girlfriend that has a wart on her nose. She may be beautiful but that wart is still there ....
These are called barrel rings and I've been bit twice on these. Both times, I bought "in-heat" and it backfired. Both rifles were .22LR and the one I have left, is a tack driver. I have a sample target and if I ever sell it, the buyer will know what he has and the target will prove how accurate it is. They are safe to shoot. I do have room to cut the barrel but for now, will just enjoy it as is. ....
As you noted, you can spot these rings, from the outside, by looking down the barrel. Sometimes, feel them by sliding your your fingers up and down the barrel. Whenever I check a rifle, I look down the barrel as well as the bore ..
Enjoy and;
Be Safe !!!