I bought a dozen or so of the Buckmaster II 4-12x40mm’s when they discontinued and ran on clearance. I kept a couple of mine, but used most on customer rifles, for folks looking for a cheap “get me shooting while I save for something better” type of optic. They’re not on the same quality par as the Side Focus Buckmasters line (I’m not even sure it’s the same glass), and not as good as the newer ProStaff 5’s which replaced them, but for an occasional use hunting rifle, they’re serviceable for the money. For the $300 original purchase price, not a chance, but for the $140 blow out price, they’re great. I do like to have parallax control for 300yrd shooting, but for a big game hunting rifle, the target is big enough to limit your vulnerability to parallax error. Mine were almost all BDC reticles, which I detest, but again, for limited use, limited expectations, they work well enough.
My biggest gripe with Nikon riflescopes in the last 20yrs has been the lensing at high magnification. It’s not bad for short runs in the scope with a big game hunting rifle, but it gives me a splitting headache if I use them for long runs, such as pleasure plinking, spotting impacts for other shooters, or colony varminting. None of which I expect will apply for your 300wby.