ID Grooving 316 Stainless Steel

I’m using a .070″ Width ID Groover, solid carbide. ID of the bore is .734 and my ID groove OD is .819″. I’m only going about .040″ deep and I keep breaking these damn things after 6 or 7 pieces. A good amount of squealing going on as well. Spindle direction good. Coolant good. Currently at 250SFM and .0005″/rev. Was at 100 SFM .0015″/rev. Neither seems to get the job done. I’m not pecking, just a straight .040″ plunge. Any ideas?