Re: Spotter or Binos?
Based on primarily needing a range optic for spotting hits on targets (paper and steel) out to a max range of 600yds...I'd stick with a spotting scope personally.
Binos are great for general observation and viewing hits on paper targets at closer ranges (and even on steel at somewhat longer ranges). They are also excellent given their size/weight for ease of transport/humping them around the woods and up/down mountainsides while hunting, etc. However, for your purposes, I think a spotter would serve you better. This is based on several factors, but primarily one of magnification, optical quality, and stability which all improve the quality of the image you'll attain at longer distances. Even the best binos, including the higher end options, are going to get you into the 8x-12x magnification range...maybe 15x if you go a little bigger (that is, unless you go with a set of Big Eyes which would be tripod mounted, heavy-duty, etc....and HIGHLY expensive). That simply isn't enough juice to spot hits on paper at extended ranges even with ideal environmental conditions, a stable platform to brace the binos to, etc., etc. On the other hand, it is possible to get a decent spotter with magnification ranges into the 35x and higher ranges while maintaining excellent imagine quality, color resolution, etc. With the spotter, you also get bigger, often brighter glass.
Anyway, I am sure one of the optics gurus can better explain all the details/specifics better than I can, but personally, I'd opt for a spotting scope if I were in your shoes and I'd certainly grab my spotter over my binos for long-range work at the range.