Bolt nose options

[916dude!]

I am planning on having a rifle built and using a Defiance Machine Deviant action. I see on their website they have different bolt nose options. What is the purpose or functionality of the different bolt noses? I.e.- cone, flat, and recessed.
Here's their options link-

http://defiancemachine.com/options/

 

[blackfoot]

Re: Bolt nose options

Cone is for a single shot. Not sure about the flat other than a claimed improvement using the M16 extractor.

 

[916dude!]

Re: Bolt nose options

Thank you for the info.