Will it be stable to shoot a 350 grain arrow out of a bk2 that is capable of 330fps+? Actually i plan on shooting it out of my patriot, but have always wondered about this. Thanks in advance.

As long as the arrow is spined properly for the poundage and you are at or above 5 grains arrow weight per pound of draw weight, no prob...

These limits are based on a 30 in. draw, if you go over 30 in draw your bow will be storing more energy due to the increased draw length, this can be damaging to the bow. The AMO puts out s chart based on the 6grain/lb rule which shows this nicely. Conversely bows under 30 in store less energy so 350 grn should usually be safe(check with the manufacturer first though)