In general, I have found bows of this type have levels between 4 and 12 percent. Refer to the force-draw curves in a Figure 1 . Observe that all three curves show a bump at the end of the dwell area which, in all cases, establishes the peak draw force. In my opinion, this makes the bow more difficult to draw and tends to make the letoff more pronounced. I prefer a force-draw characteristic that peaks at the beginning of the dwell and then falls off slightly before beginning the letoff.
Dynamic tests employ a shooting machine and a double-chronograph arrangement.
The first chronograph, a Model 1000 Custom Chronometer instrument, is located 3 feet downrange from the back of the bow. This is the standard unit. A second checking chronograph is positioned immediately adjacent to the standard instrument. Six test arrows ranging in weight from about 384 to 652 grains in approximate 50-grain increments, are each shot a minimum of five times to obtain credible average velocity values. The experimental data establishes a theoretically correct curve of virtual mass.