True, you need groove size, most Rugers I have measured run at .430". .432" throats should be good. Mine are larger at .4324" and will shoot .430 to .432" boolits.
Leading near the cone sure says the boolits are skidding plus a poor lube.
You did not say the load used but a very fast powder just increases the problems.
I get fliers with softer lead but as much as 6" means your case tension on the boolit is not even from case to case. I bet anything you will feel each boolit seat different from very easy to some very tight. Putting pig snot on boolits just makes them break loose too early.
Next, get rid of the magnum primers that also pop boolits out before good ignition.
What dies are you using, they are not all equal, I use nothing but Hornady New Dimension dies and YES, the expander is made for jacketed. Make the boolit tough enough to expand the brass when you seat. If you can't see the boolit base and ripples from GG's on the brass you are not good enough. Don't hunt to make brass larger with over size expanders, things will get worse.
You need a total review of loading the .44, it can be a bugger.
Do not over crimp, just enough so boolits don't move from recoil. Tension is more important.
Attachment 162911 This is average at 50 YARDS and I consider I had two fliers.
Attachment 162913 This is the 265 RD at 50 and the can at 100 yards. I hit the rail once so aimed higher for the last shot. This boolit has held 3/4" at 50.