Any boolit profile should feed flawlessly in any of the new Ruglins. Reason being they are breaking the sharp edge on the chamber mouth on all the guns.
Read this; https://castboolits.gunloads.com/sho...lin-1894-rifle They are doing this during chambering now so you don't have to. Chambering is being done by Single Point Boring on Strait Wall Chambers instead of using a Chambering Reamer. Simple to add a Small Radius at the beginning of the finish pass.
SWC's are the preferred boolit style for anything .357 and above. Keith invented it and he got it right. No need to look elsewhere. That said just about any boolit style will work well on the receiving end from a .44 or .45 just because of the size of the boolit. Anything weighing 250 gr+ traveling at 1600 fps + will take down just about anything in N/A. The 310 gr Lee .44 cal. Boolit with 2 Crimp Grooves and a Gas Check is an inexpensive way to get into "Heavy for Caliber Boolits." They are not hard to get above 1500+ fps from a rifle and that puts them above Low Recoil 1 oz. Shotgun Slugs running 1300 fps.
The good thing about the new Marlin Rifles, is that the .44's and .45's both have 1:20 twist barrels so they will stabilize longer/heavier boolits so you don't have to drive them at Warp Speed to get decent accuracy.
MY 1894CB 24 from 2005 has a 1:38 twist barrel and I have to run my 250-260 gr SWC's at 1600fps+ to get good accuracy. (2 MOA with Iron Sights.) There is a reason it has a Big Pachmayer Recoil Pad on the back end!
Anyway I am very enthusiastic about the New Marlin Rifles. Just be patient they will arrive.
Randy