X3 on the Rinehart target.
So much depends on arrow setup as to whether the BHs will hit exactly with the FPs. To me it makes sense that a BH might hit a bit lower due to increased drag over a FP. So if that happens, no big deal just adjust the scope. But if it's off in windage, then you need to look at the arrow. Things to try:
1) square the insert
2) align the spine of the arrows the same - try using a different cock vane
3) on a 3 blade head, align the clades to the vanes. A small rubber O ring sometimes works and keeps you from having to turn the inserts or refletch.
Don't assume your fixed blade BHs will fly the same as a FP Test everyone - at least once to verify.
All that being said, I shoot fixed blade heads over mechanicals all day
"Remember...always drink upstream from the herd."
Slick Trick, Magnus, & Montec
Black Eagle Executioners & Zombies, Easton FMJs
2" Gateway Rayzrs, DeerBoyArchery Strings