This should be a fine firearm. I'd shoot it and see how it works...if it is accurate I would either leave it alone or if it annoys greatly the judicious use of epoxy died brown to match the stock and release agent on metal would fix it.
I had one of these when they first came out. They are a quality rifle without the additional tang safety and rebounding hammer of the later Winchesters.
The action is strong, much stronger than a Marlin and it also allows a longer OAL to cycle through the action. The chamber has no throat and this may effectively limit the OAL that you can use. You can always opt to have the throat lengthened. The barrel dimensions are tighter than you generally see on Marlins. I've slugged a few of these Miroku barrels and they measured 450 (land) / 457 (groove). Accuracy was excellent and the rifle deserves some sort of tang or aperture sight.
The carbine stock is fine for light loads but it's design is far from ideal with heavy loads. There are leather butt pads you can buy that may help. If you can find one, the buttstock from a later production Win 1886 lightweight would be a vast improvement.
On my rifle the mag was loose allowing the tube to move fore and aft. It's movement was essentially limited by the pin that runs through the barrel band that retains the forend. With heavy loads the pin would bend. If yours has the same problem I would look to reduce the movement and tighten up this area. I simply replaced the pin and eventually sold the rifle.
I like it! And I'm not a real fan of the 45/70. But those Browning SRC's are real nice. I prefer them over the rifle for aesthetic appeal!!!! Very nice!!!
I am a fan. They are very well made, for sure a better made gun than the late Winchester and even better than the original 1886 in terms of metallurgy. I have had several and now have a high grade. I like it a lot and I don't care for many reproductions.
It shoots great and I use it for rabbits mostly, some day I may take it big game hunting if I don't use one of my original Winchesters. I have shot deer with the Browning rifle...