loading copper bullets

[9x80Drilling]

Let me preface my questions by acknowledging that many or most here on the forum enjoy casting their own bullets for their firearms. But for the sake of experimentation, I have over the last 20+ years tried various Barnes X copper bullets in my rifles with really varied results.

In both my 8x57R and 9.3x74R drillings, I've achieved acceptable hunting accuracy and killed many antelope, deer, and elk with them. However, in my 9x80R drilling, I've been unable to load rounds that don't scatter all over the target. Likewise, copper loads in my .45 Colt Rossi 92 also scatter. Both of these rifles group well enough for hunting with jacketed bullets, the drilling with Nosler Partitions, the Rossi with Hornady XTPs.

I have tried several powders with drilling loads but only my favorite Lil Gun in the Rossi.

Has anybody found any secrets to loading copper-based bullets in rifle cartridges that otherwise shoot accurately in their guns?

Thanks for your consideration.