Greg, that's one of the reasons that the late Stan Ware had his reamers done with
no throats. Stan throated in a seperate operation so as to have control over that critical part of the chamber. Done as a seperate operation, throat length could be optimized for the bullet being used. Plus, it allowed experimentation with different throat diameters.
For the .30's, Stan's collection of throating reamers were .3083, .3084, .3085, .3086, .3087 and .3088 .....
measured, not assumed . At different times, we tried all of the diameters in our 30 WareWolfs, 30BR's, 30BRX and 30 WolfPups.
A chamber length checker plug as Russ Stiner posted is a must have. Randy's observations on the 45 degree angle is spot on.
Good shootin'.
-Al