I've done what I stated in the earlier impression...
Made some Dummy .357 rds ( no primer / no powder ) but correct OAL for the rnd. Then load them in the magazine & let it remained loaded,
to see if the magazine spring would relax a bit & make loading rds easier. I'm happy to report that my plan worked..or at least helped.. a great deal.
Loading rds wasn't as easy as I believe it SHOULD be, but it certainly was a LOT BETTER.

Able to get rds. past the edge of the loading gate ( where rds. seemed to "hang up" ) without bruising my thumb / braking my thumbnail from the effort.
A few rds did hang up a bit, but on this range trip, I was able to use another rnd. to push the stuck rnd. into the magazine.
I do plan on re-using my dummy rds, keeping them in the rifle until next range trip, to see if condition continues to improve.

Though I used a different bullet for my dummy rnds. ( Hornady 158gr XTP / JHP) because of the different ogive, and also because the XTP is a fully jacketed HP.
The last range trip I was shooting a "short jkt" / hp bullet, that has a band of exposed lead between the Jkt on the base of the bullet & HP tip.
I was shooting those because all my .357 loads I had in my ammo stash are loaded with those bullets. That bullet, or a similar 125 gr. short- Jkt HP bullet.

To determine if the experiment helped, I took the same short-Jkt HP loads that had been giving me issues on my last shooting event.
Again, issue seemd to be much improved, I shot about another 40 or more rds. thru the rifle.

I also developed a routine to keep better track of where my brass goes, after it's ejected.
After firing, I stand the rifle so the butt plate is down ( muzzle pointing straight up) and work the lever action with my right hand, and place my left hand over the ejection port, so when the brass ejects, it hits my hand , where I can catch it (most the time) or,...it falls on the ground , at my feet.
Not perfect, but I don't have to go searching thru the grass behind me, looking for my fired cases.

I'll probably order a spring kit , to replace the ejector spring in the distant (someday) future.

Ordered some new powder to load a few new magnum loads, for both this rifle & the marlin 1894 ( 44 mag)
Couldn't find H-110, A/A #9, or 2400 in stock @ MidSouth, so trying a # of Ramshot Enforcer, see how it works.