Having covered some of the general considerations on choosing a starter precision scope, let's spend a couple of minutes on what configuration it should be.
Let's assume that you decided to spend a little money and that we have moved beyond the $300 range of SWFA fixed power scopes.
What should you be looking for?
Let's start with the magnification range: for PRS/NRL-type shooting, you will seldom, if ever, be below 8x or thereabouts. However, you are unlikely to use very high magnification with any regularity when actually shooting. It does come in useful when developing load and spotting for other people though. Some people shoot on max magnification most of the time, but they seem to be in the minority. The "classic" for lack of a better word configurations for this are 5-25x, 7-35x, 5-30x or thereabouts. Where do I fall on this? in a slightly different spot from what many seasoned competitors seem to do, so take it with a grain of salt. I really prefer to keep low end magnification at 5x or less because I spend a good amount of time shooting from wobbly-ass (technical term) positions. There are two reasons for that: I want to be ready for hunting when the animal invariable presents itself in the worst possible way and because I found that my prone/bench/barricade/tripod shooting got noticeably better when I started practicing sitting and standing with no or minimal support. I suspect that it has really forced me to focus on natural point of aim and perfect breathing/trigger synchronization. For these odd shooting positions, low magnification is the way to go (for me). High magnification seems to matter less for me than I expected, so anything 20x or above is sufficient. Often times 15x top end is sufficient. In practical terms, the goldilocks configuration for me is something like the Razor HD-LHT 4.5-22x50 https://bit.ly/3mbUNGs, although a big part of that is its light weight (think of it as a near ideal NRL Hunter scope). Somewhat heavier Element Nexus 5-20x50 is another good example of such a design https://bit.ly/3lz66qN. However, my precision rimfire rifle has the larger March 5-42x56 https://bit.ly/3wNfknM on it. Somewhat paradoxically, I often shoot at targets of very small angular size with the rimfire rifle and since I do so at closer distances, I can actually take advantage of high magnification without atmospherics getting in the way. However, I still have that 5x low end that is sufficiently low to give me a fairly steady image when shooting unsupported or with poor support. If you are building a larger/heavier rifle anyway, in the grand scheme of things, there is really little downside to a larger 56 mm scope that goes to 25x or higher. I have talked about these in the past and there is really a lot to choose from there. These are mostly Japanese-made designs and, ordinarily, I would just recommend to look at reticle options and go with the one that appeals most to you out of a variety of offerings from Vortex, Delta, Athlon, Trijicon, etc. Unfortunately, that is not always the best way to go with people new at this. They do not yet know which reticle works best for them. I used to lean toward suggesting they start with a simple-ish mil-scale reticle like March's FML-3 (I sorta designed it for that), Leupold PR-1, Leica's L-Ballistic, etc, but I changed my mind after going through this exercise with a few people. If you are trying to figure out how you prefer to shoot, the reticle and the turrets have to be able to support a variety of shooting preferences: dial everything, dial elevation/hold wind or hold everything. That means the reticle has to be a relatively uncomplicated tree-type design that gives you the right holds without being intimidating. That rules out Horus reticles right off hand, but leaves us with a variety of options: Vortex' XLR-2 and EBR-7C, Athlon's APRS6, Leupold's PR-2, etc. Any of these designs is sophisticated enough to to serve you for a long time and unobtrusive enough to not get in the way. Most importantly, after spending some time with one of these, you are likely to develop a good understanding of what works and what does not for the way you shoot. Given that, it is no wonder that I end up recommending Vortex Razor Gen2 4.5-27x56 to a lot of shooters. I am sure Razor Gen3 is not too far away, but the Gen2 has had such a lengthy and consistent track record and there are so many of these out there (I can't disclose the actual number, but I was SHOCKED when I figured out how many of these are out there) that it is hard to vote against that track record when making a recommendation for someone new to the sport. Add to that Vortex' stellar reputation for customer support and Gen2 4.5-27x56 with EBR-7C looks like a pretty safe recommendation https://bit.ly/3il7M7p With all that, EBR-7C is not my favourite reticle (I like XLR-2 in the HD-LHT a good bit more), while Athlon Cronus 4.5-29x56 comes with a cleaner looking APRS6 https://bit.ly/3FiYpxS Cronus does not quite have the length of the track record of the Razor Gen2, but this basic design has been around for quite some time in many different iterations and has proven robust. Athlon's factory support is also very good.
Lastly, it is worth mentioning Leupold's Mark5HD 5-25x56. I have really liked the Mark5HD series since it was introduced, but there were two things preventing me from recommending them more than I have been: reticle selection and upcharge for reticle illumination. Reticle selection, in some models, has been rectified with the introduction of the rather nice PR-1 and PR-2 designs, but the cost of illumination is still a problem. However, if you can get LE or military discount, the 5-25x56 with illuminated PR-1 reticle is very compelling https://bit.ly/3eevSNR It is a pretty nice scope as is, but Mil/LE discount really moves it to the forefront of the bang for the buck discussion.
Is reticle illumination important? opinions vary, but I like to have it largely because I spent quite a lot of time shooting on low magnification. For a scope of this type, I strongly recommend going with an FFP reticle and it will look fairly thin on low power. That is where I use reticle illumination the most. If that is not something important to you, the same Mark5 is nearly $600 less: https://bit.ly/33Fq51O
What other futures should you be looking at? If you are spending some money, elevation turret must have a zero stop. Locking elevation turret is nice to have, but not required. Zero stop, however, will make your life a lot easier. Windage turret should be either locking or covered. I seldom ever use it personally and I am always concerned that it will get inadvertently adjusted from zero.
Lastly, use a sunshade. Yes, it makes the scope longer, but in most situations, that is not an issue. Optically, there is never a good reason to leave the sunshade off the scope.
To summarize all this: when advising new shooters, I am looking for track record and versatility above all else. A good way to think about it is that I am not looking for a solution that will make your existing skills shine brightest. I am looking for a solution that will let you develop those skills.