I started myself down the single shot rifles a couple years back.
First one was the CVA 444, scout, takedown version. Was a great shooter, but was not able to take any game with it, even though I carried it for miles. I have a stock sleeve for extra ammo, and practiced quick reloading with it always, and even on range trips.
Really wanted a ruger #1 303 brit, but with them being hard to find, I convinced myself to just get a nice stainless #1 and then have it changed up to a 303 brit. I ended up getting a 204, and just fell in love with the platform. Unfortunately I ran into too many rifle projects and ended up selling the 204 before having it converted.
That is when I ran into a new stainless, laminate stock 450BM in the #1. It has now become my primary hunting rifle, and I was able to use it on some big game this year with my elk and moose.
The extra practice of quick reloading paid off as well, as I had to do a quick follow up with the elk this year. With some practice it is remarkable how fast you can reload a #1 with the empty cartridge being removed with the dropping of the lever.
After plenty of research, I ended up using the barnes 290 gr TEZ, muzzleloader tips, moving 2260 fps. Good out to 350m.
Even experimented with the .458 solid copper tips pushed through a few sizer dies to get down to .452. These worked fine as well at the range, and gave me options if I ran into hard to find bullets. I was able to find a few boxes of cheaper 300 gr flat point tips for range fodder as well, so I have plenty of practice at the range, for a decent price. Did some reloading work in the reloading forum as well if you want to see that.