I bought some CX250's this summer, then messed up and cut them too short. I have one bow with an elevated rest that I can shoot them off of, the problem is, for them to tune well, I need a 250 grn broadhead. I'm having trouble deciding on what setup to shoot, I know that some of the steel inserts were breaking, but not which ones. I prefer a three blade head. Any suggestions?

I would go with a 125 gr steel adapter and 125 gr woodsman head . The 75 gr steel are the ones that have broken.  Drew

What Drew said  

my brass inserts are 100 grains I think and make the shaft like 1/4" longer ... maybe not quite 1/4"   I got them at a local archery shop though, no idea where to buy them on-line like these

3Rivers. They are a sponsor here too.

You may also want to try the glue-in Brass Broadhead Adapters (not Brass Inserts).  They come in various wts., these would replace your standard inserts.

I have seen that some of the 75grn adapters had broken as well..
I am unsure if it is as much of an issue as some make it to be.. As I have had the alum adapters bend... The only report I saw said they had broken in the far side of a pig... I think that the force we worry about is the force when the arrow is pushing it into game, the force that seems to be breaking these is a shear force probably encounter after the arrow is in and the animal is running. (You know the shoulder or shield putting a sideways force... I don't know, but I can't see the real issue as I would think it would be stronger than the shaft itself... Much stronger than a wood shaft...)

By that time the purpose has been served... I would doubt that the force required to cause these adapters to break would exceed the force required to cause the damage alum inserts...
I have seen no problems and one that I shot over a wound up whitetail embedded into an oak hickory stump and then was used 3 days later to anchor a small whitetail.. I only had to touch up the broadhead... It's in my quiver today ready to go to work...