You are right about the longer term committment to this fund. It's not day trade stock. It's a hedge against inflation. Compare USAGX to a small cap like USCAX on a 5 year or longer chart and you may change your thinking about putting 100% of an IRA in any one fund despite your youth. Although I wouldnt be getting into small cap just yet, you may be limiting your total growth by half over a very long haul. It's called Diversify.
USAA suggested trimming gold positions earlier in the year. They recently came out and said that they were going to maintain their current gold positions. I think $25-$27 is a good entry point into this fund. I left earlier this year after holding for two years...am going to reenter soon. USAGX generally represents 15% of my portfolio. Good luck!