OK, so maybe this is overkill, using SolidWorks to design, check or specify a forming countersink for your turret but it can help prevent errors. This is for forming countersinks that do not create 'bends' or 'extrusions' to create the countersink, but that create a 'coin' or 'form' that is entirely within the material thickness.  I made up this SolidWorks 2012 version file with a Design Table based on Wilson Tools formula for determining countersink pre-punches. To use open the file with SolidWorks 2012 or newer, you'll be presented with a model of the countersink.  Then go to your Configurations Tab and right click on the Design Table and select Edit Table. (You may have to Drop Down the Tables Folder to show the Design Table.)  If you're asked to Update the Table, just click OK. A window opens that should be self explanatory.  There is a Drop Down arrow to the right of the CSK ANGLE allowing you to choose from the common angles of 60, 82, 90, 100, 120 degrees.  Then Enter your desired MAJOR DIAmeter in inches. The table immediately updates with your pre-punch and a minimum material thickness. If the Minimum Material Thickness is more than your material thickness, you 'should' change/increase the MINOR DIA to avoid your damage to your countersink.  Click anywhere on the screen outside of the Design Table to allow SolidWorks to update the countersink.  I show a chamfer on the tip of the countersink, Wilson Tool does not supply the countersinks with this chamfer. I applied the chamfer manually to assist alignment and prevent damage to the countersink dies. If you use the countersink as a one-hit with no pre-punch I would guess that this procedure is not for you.  You can download the SolidWorks 2012 version file from my Google Drive here: https://drive.google.com/file/d/0B_Prq1R5dYgmN1FzTVBDQnBNbzQ/edit?usp=sharing and feel free to share this file.  If you have an idea on how to improve this file please do so and share it too. You can remove my Copyright notice and LinkedIn link though I would suggest adding yours if you do improve it and repost the file. Please add a date when you did and what you did as an improvement.  There is no endorsement implied by Wilson Tool or SolidWorks. The Design Table is locked to prevent accidental changes and it can be simply unlocked, there is no password.