Is the newly manufactured ammo corrosive now?
If it is from the big name manufactures in the US no. Otherwise it depends where you get it from and who made it. I got some surplus ammo from the middle east for my 303 that was made within 5 years of purchase and I was given the option of corrosive ammo from country X and non corrosive from country Y.
A good gun shop will know what is what....