Thank you for all the great advice.
It took me this long to have time to pull the rifle apart to see what is going on.
It is the sear. A replacement is now on its way.
A previous owner [my dad bought it for me and can load a cartridge or clean a weapon, but is by no means a gunsmith and doesn't try stuff like that] had filed the tip off the sear. Yes, this made it a light 'hair' trigger to fire. But, the hammer [what savage calls it, even if it looks more like a striker to me] bounces off the sear when I forcibly 'slam' the lever home. If I gently use the lever, the hammer stays on the sear. If I 'slam' it, the hammer bounces up off the sear.
So, I have new springs and a new sear on the way from numrich.
Once I get them I will proceed to carefully reassemble.
I'll also pay special attention to the hammer rebound spring so that I don't lose it as well.
Thanks for all the great tips and info.
44AMP, can I remove the rotary magazine without disassembling it? I'd like to do a detail clean, as there is a lot of gunk inside the receiver.
I loved the balance and accuracy of this rifle. Now I'll be able to shoot it again [haven't fired it since observing the problem: used snap caps to replicate]!
I haven't begun reloading yet, but this will be a fun round to reload for. I am thinking I may start keeping my eyes open for a .308 version sometime soon. I know they are ballistically similar, but I like the lower cost and greater availablity of .308 ammo over .300savage ammo. Reloading solves this though.