The standard craze these days is weight forward. I'm with Jack on this one. I wouldn't put pins in the shaft. Upsetting the grain integrity doesn't sound wise. May have gotten away with it on 1/2" diameter war arrows, but I just wouldn't do it. I would just use a heavier point and kill two birds, as it were. Now, how much weight? There has be a point of diminishing returns, somewhere along the way.