Straightarrow,I just made an arrow that had an foc of 23.6% that was under 400 grains.
The secret was it was a traditional light stinger that is tapered and has several wraps of carbon up front.I had a 135 gr point and a normal insert that I did not weigh but I believe it was around 23 grains if memory serves me.I also used 4" feathers.Total weight was 399 grains.
It can be done but it isn't going to be done with normal arrows.
I am off to see how it shoots.