The 350 legend is actually a 9mm not the same as a 357. The only advantage I see is that it shoots very accurately . Its a pointed boolit also, that has very little drop out to 240 yards, its maximum potential for deer and smaller game. Advantage 2 over the 357 max is that Mike Bellm Is having a hard time getting the Max off the ground. It uses pistol boolits and the 350 legend has a designed rifle boolit and one is a hunting round. I talked with Mr Bellm at length about the Max. He is very passionate about it. Maybe if he went with another platform other than single shot rifles. But the 350 legend has an actual big ammo/rifle company pushing theirs. Rifles and ammo. Also there is already a BFR Revolver in 350 Legend. Ruger is making other rifles in the 350 legend along with other companies. The AR platform is a BIG industry and is selling out constantly of the Legend. Make no mistake. The Legend is here to stay. Yes it is similar to the Max, and is slightly out performed in power. But the Legend in a 16-24 inch barrel is very accurate and is a real rifle boolit. Balistics by the inch changes very little, from 16-24 inch, only about 180 FPS. It does have a place in the 250 yard hunting range. But what it has that is most important is BIG backing. I would bet it is here to stay.
I have known Mike Bellm for 40+ years. When they first came out, I bought a Dan Wesson in 357 Max and used it to hunt both Mule and Whitetail deer. Took a Whitetail at 175 yards with the DW. It also became my gun of choice for shooting NRA Pistol Silhouette (much more accurate than my Ruger Redhawk in 44 mag). I have also owned a Marlin 1894C in 357 Magnum for about the same length of time.
About ten years ago I set about to convert the Marlin to the 357 Maximum. I like the idea that I can use the same cartridge in my rifle and revolver. First let me dissuade anyone from the idea that it cannot be done or is even difficult, and also, that the pressures are too high for the Marlin. Mike Bellm's knowledge on chamber lengths and throat configuration made him the best choice to rechamber the barrel. After that was done I put about 50 rounds one at a time through the rifle. It was amazingly much more accurate than when it was a 357 Magnum. Then the fiasco began.
When the 357 Maximum first came out, developed for pistol Silhouette competition by Elgin Gates, who founded IHMSA, there was a rush to chamber the Marlin Carbine in it. Some smiths knew what they were doing and most didn't. I, way back then, fired two rifles converted by two different smiths. One was flawless behaving exactly like the original in feeding, firing, and ejecting. The other had the throw of the lever changed and the rifle would hardly feed the cartridge or eject the spent case.
Bellm was not set up to do the full conversion. I found a smith who said he knew how to convert the rifle. After a year he finally sent it back to me and refunded my money. The rifle would jam requiring disassembly. I had thoroughly research the changes that needed to be made and had supplied a schematic as to what needed to be done. He apparently disagreed with my suggestions and left me with a non-functioning rifle.
I continued to look for about 4 years for a Lever Rifle expert who had made such a conversion before. I finally went with a guy who is famous for converting Marlins for Cowboy competition. I sent him the rifle and he said that he could refine the modifications to get it functioning but would not stand behind his work because it was not his modification, just a fix of someone elses. Anyway, his work cost me more than 3 times what I'd paid for the rifle, and returned it with a note saying it was a "little rough in the cycling!" For sure, it would jam due to a mis-feeding glitch that would jam the cartridge between the carrier and the bolt. . .also requiring disassembly to free it up. No warrantee!!!
But he had progressed the evolution far enough along that a substantial amount of work with a jewelers file on my part got it feeding perfectly. Worked just as smoothly as when the gun was new. Too slick! I discovered that although it functioned smoothly apparently the process of slicking the action up to allow fast function as he did for the competition rifles, there was no longer a disconnect of the trigger until the bolt came to full battery. If the trigger was pulled at any point after the bolt was beginning its travel forward, the hammer would fall. Luckily my discovery of this problem did not strike the primer hard enough fire the less than half-chambered cartridge. Six years later the rifle still sits. A conversation piece.
I certainly strayed in this tome. But, to reiterate, the Maximum has some bullet advantages over the Legend, the Maximum can handle .358" diameter bullets giving a wider range of bullet selections, at lease in my research, for rifle work than is available for the 9mm Legend. One last tidbit, after the re-chamber, of those 50 test shots 20 were at milk jugs of water at 300 yds. Yes, scoped and on a bench rest, and all the 180 gr JHP rifle bullets, designed for the 35 Remington, expanded well.
I just found my old post about the Marlin, done back when I still remembered the velocities.