Remap it to R1 and you can just hold it down and fire with R2, assuming you can claw grip it. If not, try R3. Its not really the end of the world but, unfortunately, the alt-fire really unlocks the potential of several of the weapons. The alt on the repeater basically means you can just spam fire the entire time and then just run around avoiding things. Its really awesome.

Have you looked into the various weapon perks? Once I learned about a few of them I was way better at tailoring my weapon choice selections and it made the game MUCH easier. Power Generator FTW!!!

Yeah parry sucks. Its only really good for long range to clear the red out of your path for movement. Up close its worthless.