Symmetric encypher with private key decypher

I am looking for a way to use symmetric encryption on a day-to-day basis, using a key-file of some sort to decypher the file. I have decided that using my asymmetric private key in the following way was the best for this, using the following method:

dd if=/dev/urandom bs=1024 count=1 | gpg -c --pasphrase-fd=0 -e -r mikmorg "$1"

Is there a better way to do the above? By better, I mean standard / portable. This is just an idea I threw together, and hope its the best. If anyone has any ideas for me, I would love to hear them.

Also, gpg wouldn't cut-out part of the stdin key from dd (expecting text-only), if it encountered an \r, \n, or \0 character, would it? If thats true, I definitely need to find another method.

Thanks,
 Mike Morgan