I just finished up a spare parts build the other day, a 20" bipod rifle. This won’t have any BUIS - optics only. It’s not meant to be a true precision build; the barrel is a BM 20" 1:9 fluted HBAR that I picked up years ago and never used. I plan to use this on paper and metallic targets out to about 300m which is the farthest I can shoot locally. Anything beyond that and I’d be reaching for a 7.62.
Is 1-4x enough glass for a general purpose 100-300m rifle? I have no experience with low magnification scopes, my .223 Rem 700 wears a 4.5-14x and my 10/22 build has a 10x.
I would buy a 2.5-10x for that gun. But some people are able to shoot very accurately with a 1-4x at that range, but I need more magnification though. YMMV.
I have to say I’m nervous about committing to a 1-4x class optic and then finding I always run it at 4x and want more.
One of the new Nikon M-223 scopes is looking interesting and appropriate for this rifle, the 2-8x with BDC calibrated for 55g (appropriate for the 1:9). I’m a long-time Nikon user first professionally and now as a hobbyist, and my Nikon 4.5-14x has proved to be a hell of a scope on my Rem 700.
Looks like you already know what optic to use. I also plan on buying a Nikon M-223 in the near future (1-4x20).
That’s the one I was considering. I suppose it wouldn’t be a waste even if I decided to go longer later - I could always move a 1-4x over to a 16" build, like the Noveske Recon I’ve always wanted. 
Nikon is GTG. To be truthful–I’m not sure why I’m high on this new optic series from Nikon…but I am. The price/quality ratio seems good and I do think it will be money well spent (if a quality, no-frills, magnified optic is your goal.).
I just wish Nikon had illuminated this line…
Same here. The 1-4 with a lit center dot would have been nice. It would have killed the price point, though.