But that cutter is just a basic high speed steel endmill. Very inexpensive. Here's a stupid cheap one for example https://www.shars.com/products/cutti...ingle-end-mill. You want a 4 flute square endmill, 5/16" diameter, 3/8" shank. No need for center-cutting. No need for carbide, fancy coatings, or some $20 MSC or Grainger option. eBay littered

3k is short life for the original cutter. Use Dillon or FA spray lube (or homebrew lanolin + 100% alcohol). And let the cutter do the work vs jamming the cases into it forcefully. Both of those will extend the cutter's life.