when ASCII armor can I change the extension.

I am using gpg4win-2.1.0.exe to sign and encrypt with text output a file to transmit to a vendor. When the file is made, it puts an asc extension on the file. The vendor requires that the file ends in .pgp

I have my users simply rename the extension on the files before sending them, but is there anyway to modify the default extension to .pgp so they can skip that step.

Thanks for any help.