Domesting Shorthair's question about Pain

Question

I adopted a 4 year old, previously stray, cat in January. He's the best. However, over the past two months I noticed him limping more and more in his back right leg. Additionally, he wont put weight on it when he's jumping up or down. We went to the vet last week and after looking at the xrays the vet discovered that there are old bb gun bullets/pieces of bullets lodged in his hip and shin.  He was put on buprenorphine for a week to see if his behavior was different with his likely pain taken away. He has definitely been in less pain this week. No limping, even weight distribution of his back legs and playing even more than before.

My vet suggested just keeping him on buprenorphine for the foreseeable future. Is that what you would recommend as well? It seems like I wouldnt recommend to a human to stay on opioids for the rest of their life and I'm nervous about doing that to my cat. Are there possibilities that removing the metal could help take his pain away? He was a stray so no idea when the injury happened or how long the metal has been in there.

Pain in Cats