Is there anything I can do to increase my chances of deploying in the Missouri Army National Guard after volunteering?

Besides changing your Volunteer status, you can also try checking out MOBCOP website. Also, get with your Chain to contact your BN S3 and see what possibilities there are for your rank/MOS. Good luck.

It's probably going to be tough as an ammunition specialist. The ARNG doesn't typically mobilize as individual augmentees, so in most cases you would have to find a unit deploying. The 1-138 is deployed right now, which means it'll probably be 5 years or more before they mobilize again. I would imagine the rest of your state is in a similar position on the new SRM Model.

As MSG (Join to see) said, MOBCOP is probably going to be your best bet. I would look at MOS immaterial positions in addition to 89B. You'll probably find more options.

Research. Call around and find a unit that is deploying 3-6 months out and ask to transfer in. Don't be stuck with the idea of deploying with your home state-there may be a unit (Kansas, Oklahoma, Arkansas) that is getting called up. Call an Intrastate Transfer Manager at your state HQ and that of neighboring states-they definitely know where troops are needed. When units are short handed they tend not to worry about your MOS. They may be able to re-train or might even assign you to unit without re-training. Plenty of Mechanics, Cooks, and other MOS soldiers ended up elbow to elbow within an Infantry unit during deployments. Best of Luck!