Often our primitive bows shoot poorly with lighter weight arrows. These bows naturally have more efficiency when they have an arrow they can lean into! The typical ratio is 10 grains of arrow weight for every lb of draw weight. So your 400 grain carbons may be leaving too much kinetic energy behind in the limbs, and that often translates as hand shock.
If you can get something closeer to a 500 grain arrow you will probably still see the 150 fps, but have increased kinetic energy in the arrow simply because the bow is able to give more to the arrow!
Another benchmark we often use a simple rule of thumb that the speed of the arrow in FPS should be at least the draw weight plus 100. If you are getting 150 fps, that's better than the 100+47 rule. Not bad, son, not bad at all!
Now to the critique. You made a glaring error that needs to be fixed. You didn't post a picture of the bow! Tsk, tsk. If you have been lurking here you would know there is nothing we all like more than photos of the different bows, arrows, knapped heads, kids with bows, dogs with arrows, cats in piles of osage shavings, etc!
Welcome to the addiction!
