groove for a bayonet cap to fit in.

See the file I have attached.

I made a groove in a cylindrical part using the wrap-deboss command and the groove has a taper on the vertical cuts but not on the horizontal cut. An end mill would not machine a taper but a perpendicular groove normal to the cylindrical surface. Need help with this as tech support said they cannot come up with a solution. Anyone have a solution to model this groove???

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