Since you said "new" I assume you meant current production, not just "new to you", the repair most likely will be covered under warrantee.

In the OP you said "...I had just gotten an ejector rod removal tool from Brownell. So I fill all the cylinder with brass and I tighten the rod as tight as I could...." Yes, you very likely caused the damage! Even though the parts involved are all heat-treated they are also small and, as a result, can be damaged if abused. In this case there is a slot in the extractor which causes a weak point. Tightening a screw imposes radial as well as axial forces on the system.

If you have occasion to work on another S&W extractor rod, just "very snug" is tight enough. Tighten it until the rod is felt to firmly bottom out, then not more than 1/8" more rotation measured on the rim of the tool. Note that is 1/8", NOT 1/8 TURN. If it loosens while shooting them just a little mor next time.

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Gunsmithing since 1961