Many people experience poor feeding with lead boolits in the Marlin 1894 series of guns. Lots of people promote only using Round Nose Flat Point boolits to get around this. However the real performance from these pistol calibers is in using Semi Wadcutters like Lyman .429421 or 429244 or clones. As we all know these boolits were designed by Keith and Thompson for hunting but give superior all around accuracy in both Revolvers and Rifles. They will go clean thru just about anything in the US and similar sized game anywhere else. IMHO they are the best boolits for these cartridges there is.
There are about 8-10 different versions of these boolits from 215 gr (in .44 cal) to over 260 gr. with various HPs and Gas Checks, etc..44 cal SWC moulds are available from Lee Lyman RCBS, and all the custom mould makers my personal favorite being the excellent moulds by Mihec.
The biggest problem in trying to use these boolits in Marlin Leverguns is the fact that the chamber mouth is left sharp. When the Cartridge Lifter pins the new round against the top of the receiver and the bolt pushes it forward towards the chamber, the sharp edge of the chamber mouth digs into the boolit and stops it.. This is especially true with SWC's as they have a nice little step to catch on the Chamber Mouth.
I first experienced this in 2004 with my 1894 CB in .44 caliber. I wanted to use some LBT 250 gr. Wide Flat Nose Boolits I got from Beartooth Bullets but the Meplat was so wide that the chamber mouth gouged into it and stopped every round from going in the hole.
I had a real good look at what was going on and decided to break that sharp edge. On my gun I really wanted a Radius but had no way to do it without getting a special cutter made, so I used a 6 flute Severance Countersink on an extension and turned it by hand until I had enough chamfer.(.040-.050.) It took about 5 minutes to get the chamfer large enough as the barrel material is pretty soft.. I then smoothed out the edges of the chamfer with 400 grit W or D sandpaper and the result is in the pic below which I have posted here no less than 50 times!
My gun will cycle any .44 Magnum or Special cartridge, with any boolit I choose to use, as fast as you can run the lever. With no sharp edge to dig into the boolit the cartridge just slips right into the chamber. It feeds RN style boolits just as fast and there is no lead shaving to affect accuracy.
The Extractor Groove on these cartridges is .060 in width. Thus that area of the case is not supported in any way by the chamber. Also inside the case the extractor groove is actually in the sold base of the case so it doesn't need to be supported in any event..
This is not hard to do, and it works great, and is completely safe, and I hope the Mods will make this a Sticky so I don't have to post the picture and explanation 50 more times.
That's all there is to it.
Good luck
Randy