A couple of points here...when setting up for serious 3-d shooting, you want to build the best arrow you can, then set your bow up to shoot it. I like to shoot at least 10% FOC when possible. I have X-7 aluminums that are less than 6% FOC that fly great out to 50yds. I know several pro shooters that shoot similar set ups.
Also, adding weight to the nock end of your arrow will stiffen the spine.
Don`t get overly worried about a high FOC for 3-d arrows, see how they group. For hunting set ups, if you are shooting fixed blade heads, now you need to build a high FOC arrow.
Jerry, I just scrolled back to your second post and I see you are shooting a 26" arrow. If you need more weight, try shooting a longer shaft. The longer your arrow, the more flight stability you will have.