High feed endmill

Anyone ever use an 4 flute highfeed endmill. I am looking for the speed and feed for a 10mm 1m rad solid carbide it is a YG1 . The recommend feed and speed in the book is 6400rpm 551ipm .0039 stepdown. I ran it and not good. I looked in OSG book and they have same cutter and same feed and speed. I ended up running it at 6400rpm 200ipm it looked ok put think it could be better. It cut to parts prehardend h13 42rc 7x10tapered down 3inch with almost no wear.
Any help on the speed and feed would help new to this highspeed machinig.

Thanks
Mike

Mike,
I have used both of those cutters and they Kick butt as far as material removal. It might be a matter of your cam software not ramping into the work and the corner moves being sharp. Any slamming into the work or corners really does a lot of harm to the cutting edges with these tools. I am using Pro Manufacturing and the high speed functions really work well with the high feed cutters.I too used the parameters recomended out of the catalogs. I tore up one of the osg cutters right off the bat because i missed setting the ramp into the work on a pocket in hardened S-7 at 54Rc.the plunge at 340 ipm(even though only.004 deep) took the edge off the bottom of the cutter. It didn't last long after that. they seem to be able to remove quite a few cubic inches of material before wearing out otherwise. Probably not much help but there is other people out there doing this same thing. You could also call tech support for osg or yg1 they usually are a great deal of help because they want us to succeed using their products.