Can I fire cone .04 clay to .05?

I have some clay that I have built a beer stein with, and it came out great, but I need to fire it! I have a kiln, but it needs rewiring and I need this baby fired asap. I have someone with a kiln who could fire it to cone .05, but I don't know if it will kill it. The clay is Amaco white air-hardening art clay, and it says on the box you can bisque-fire to cone .04, and then glaze and fire to .05-.06. Can I just fire to cone .05? Will it explode? HELP!