You know Bow_hunter, I never put alot of thought into acceleration. We just look at the static numbers of velocity as the bow leaves. But I think you are onto something that might explain my and others results. The only part where its different is when you say KE=1/2mv^2. when velocity goes down, mass is going upbut velocity is the dominating factor in the equation, unlike the linear equation for momentum.

Thanks for posting. Its very refreshing to see someone not doa cut and paste, but actually work it out.