I do not have a chronograph. What kind of velocity would I be looking at with .44 mag out of a 24 inch barrel with factory ammo?
From my Marlin 336 in .44 magnum, with its 20" Micro-groove" barrel, I've chronographed Winchester White Box 240 gr. JHP's at 1715 fps. Accuracy was inthe 2-3" group size for three shots at 100 yds. I was using a 2.5x scope and shot off an improvised rest.
As to tumbling...I just have never seen it in 35+ years of loading for the .44 Magnum.
through Micro-groove rifling?...I've done that for nearly as long. To be successful, you need a bullet's .001" or so larger than the groove diameter of your rifle. My Marlin measures .432" across the grooves. I size my cast bullets to that dia. +.0005" and get sub 1" groups at 50 yds. They're as accurate as the jacketed variety. Too, you need a GC on the bullet...at least in the work I've done. When properly sized, lubed and gas checked, I've pushed them to factory jacketed velocities.
Soft alloys don't do as well as harder ones in a rifle in .44 Magnum, but I've never had to resort to Linotype. I use wheel weights with just enough tin added to allow full fill out in the mold, and I quench in water. Brinnell hardness is approx 12-14...i.e. medium in hardness, but the Gas Check employed makes them capable of higher velocity...1500-1600 fps, from that 20" barrel, and they're accurate and non-leading. They're nearly as fast as the aforementioned Winchester White Box 240's. I use the NRA/Lyman 50/50 mix of Alox and ?beeswax? for all my lubing, but have just as good results with Lee Liquid Alox (LLA) thinned with mineral spirits by 20%; and that LLA works well even with Lyman's #429215gc and 429244gc (old Thompson designs but very accurate in every .44 I've ever worked with, rifle or revolver.
For hand loaded jacketed bullets
I've had superb results using both Remington's 240 gr JHP's and JSP's, as well as both Hornady's 200 gr and 240 gr. XTP's. Accuracy was as at least as good as factory offerings(~2" gps at 100 yds, scoped). I've killed two deer with that Remington 240 gr JHP, chest area hits that went through and through...complete penetration, and bleed out in 50 yds or less. For jacketed bullet loading, I've been using AA#9 for years with complete success. Burning rate is similar to H-110, but different data must be used when loading with it.