Hi. Just looking for feedback. Is my arrow weight too low?  My setup:

-Black Widow KB 45#
-Draw length : 28.5"
-Arrows: Safari Tuff 500sp, 50gr insert, 125gr head

My total arrow weight is 400gr.  I've killed a few does this season with it. Did not get pass throughs. Magnus Stinger Single Bevel head. 

I tried more weight up front and it seemed to negatively impact arrow flight. I'm wondering if I need to get the 400sp, leave them long and add 200gr up front.

Thank you

Maybe it's the head?  Those Stinger single bevels look kind of blunt up front compared to a standard stinger or a zwickey.  I'm shooting longbows in the low 40's with a total arrow weight around around 10 gpp, so not much more than you and with VPA 3 blades or Stinger 2 blades (with bleeders) typically get pass throughs.   

If a heavier head wont fly, my  suggestion would be a heavier shaft.

Best of luck. 

1st id bare shaft tune an arrow just to be sure the string nock is in the right place,, if its too high I had problems with cast using heavier points.    also the description of you're arrow setup I almost shooting the same thing but gold tip classics and Im 50gr more than what you are getting but I can double check that set up later.

if you are tuned to that arrow instead of messing with another brand just go to the hardware store and get a spool of the cheapest weed wacker line,,,,,pull nock off arrow and put them in there one at a time and cut them an 1/8" longer than flush,,,, try 1 length at a time by shooting each arrow looking at the trajectory or cast and you should be able to fit 3 total the arrow weight will come up a lot and spine isn't effected that I could ever tell.

Personally I don't think you should have a problem with 9 gpp arrow weight. If you are getting good arrow flight, you may want try a different broad head.

Did you actually measure the draw weight at your draw length?