Mike;
MtJerry is right. You need a FIRM crimp to burn that 2400 powder. I've shot thousands of 250gr. Keith bullets, and I'm working on loads right now for my FA Mod. 97 44 Special. And have used 2400 in the special.
But for more velocity and probably better accuracy I would put a crimp on those 250's.
After you put a crimp on those bullets, just keep in mind that you may start to go over 1500fps with 20gr. of 2400. Which in turn might start to lead the barrel, if so drop down about a half of a grain.
Also look at it this way less powder burned means more rounds per pound.
I really like 2400, it may not give the fastest loads such as H-110 or W-296, but it makes up for it in the accuracy dept.
Good Luck and keep us posted.
Dennis