The barnes x bullet behaves much like a failsafe in that it will penetrate a great deal more than a conventional bullet(almost double according to several bullet test's that I have seen) even in lighter weights.Therefore it is possible to shoot through most of a deer lengthwise especially if it is a smaller deer.As for the 3500fps ,what barrel length and is it a coated bullet and what pressures does he load too.Is this a chronographed velocity or an estimate.