Heaviest 444 Bullet?

[cooper]

What is the heaviest bullet you think would stabilize in a Marlin lever in 444? 
 
I know that caliber was designed for a 265 gr bullet, but wonder if you could use a 320-340 gr bullet and have it be stabilized.  I don't know what the twist is in that rifle.  I'm assuming the LFN would be the best stlye.
 
I already have a 260 gr WFN for my 44 Mag revolver.  Will that bullet feed OK in a 444 lever gun?

[Veral]

  Your WFN will feed smoothly in a 444 if seated deep enough.  Just play with seating depth untill it feeds and slides smoothly all the way into the chamber, then crimp lightly with the Lee Factory crimp die.
 
  Twist rate is the same as the 44 magnums, and they will stabilize a 300 gr very well at 1800 fps plus.  With the 444 power potential, a 340 350 gr will shoot very well if the speed is upped till it flies accurately at long range.  Even a 400 gr will shoot well, but recoil becomes miserable when you get the speed up to stability.   I prefer the LFN.