Mark 5HD or SHV 5-20 for a 6.5 Creedmoor — which one actually holds up at distance?

Both will work, but you're conflating two different optical properties and that's worth untangling before you decide.

The clarity question—what you're really asking about in low light—comes down to exit pupil diameter and how much of it your eye can actually use at distance. At 600+ yards, you're shooting in a narrower sight picture. The Mark 5HD at 5x has an exit pupil of 9.4mm; the SHV 5-20x at 5x has 10mm. Sounds similar. Here's where it matters: the Mark 5HD's eye box stays more forgiving across magnification ranges because of its optical design. The SHV's eye box tightens noticeably as you dial up. At 20x in dim light, you lose peripheral reference faster on the SHV—your eye has to be more precisely positioned to get the full optical window.

On the turret repeatability claim: that's real, but contextual. Nightforce turrets do track with tighter tolerances (typically ±0.25 MOA vs ±0.5 MOA on Leupold). The practical difference? If you're making three elevation dials a day and parking it, you probably won't see it. If you're doing repeated adjustments in a day (wind calls, range changes), the SHV's repeatability is genuinely better insurance against cumulative dial error.

Zero hold is about mount quality more than optic. Both hold zero fine on quality rings.

My recommendation for your specific use case: Mark 5HD. Low-light hunting at distance rewards eye box generosity over dial precision. You're not doing PRS with 15 shots a day. You're making two, maybe three, cold-bore decisions in poor light. The optical window at 5x magnification is your advantage here, not turret tolerances.

Talk to a dealer about returning one if it doesn't feel right mounted—that's your real test.

**frm42 nailed the eye box trade-off, but I'd push back on deprioritizing the SHV's tracking consistency—especially if you're dialing repeatedly in the field.**

Here's the gap: repeatable turrets matter more than the "cold-bore hunting" framing suggests. You said you're comfortable past 600 yards on steel. That's not two shots and done. If you're ranging at 580, then 620, then adjusting back down for wind, you're asking your scope to return to zero consistently. The ±0.25 MOA spec on Nightforce isn't marketing fluff—it compounds. Three dials per day × 100+ field days = cumulative error creep. That's real.

**Why this matters for your workload:** Leupold's ±0.5 MOA tolerance is honest, not bad. On a 600-yard shot, that's a 3-inch potential variance per adjustment cycle. Doable. But if your hunting involves range-finding multiple targets or wind reassessments, the SHV's tighter spec is insurance, not luxury.

**The actual recommendation:** Start with the Mark 5HD if low-light performance is non-negotiable for your specific season (dusk/dawn only). But if you're doing any amount of mid-day glassing or ranging multiple animals, the SHV's repeatability pays dividends faster than you'd expect. Test-mount both on your actual rail if the dealer allows it—eye box feel varies by shooter, and that's your real decision point, not specs.

Barrel life on 6.5 Creedmoor is 2500–3000 rounds with quality match ammo. Your optic choice matters less than your reloading discipline here.

sarah.b, I'm tracking your point on dial consistency, but I think you're sliding toward a PRS mindset here and want to push back on the weight you're giving it for hunting work.

Here's where I land: you're right that cumulative dial error is real. But the scenario where it actually bites you in hunting is narrower than three dials per day suggests. Once I'm glassed onto an animal, I range once, dial once, and I'm shooting. If the wind shifts enough to re-dial, I'm usually repositioning anyway—not just cranking the turret again from the same position. That's the actual hunting workflow, not the range-finding-multiple-targets thing.

Where I think the gap matters more is this: if OP is doing any amount of mid-range work (400–700 yards) where he's making educated guesses on distance rather than absolute range-finds, the SHV's tighter tracking gives him one less variable to second-guess when conditions aren't perfect. That's a comfort thing, not a ballistics thing.

But here's my real question back to both of you: are we overweighting optics accuracy vs. ammunition consistency? A precision hunting load from quality brass and a tight charge will matter more to a 600-yard cold-bore shot than whether his turrets repeat to ±0.25 or ±0.5. Have either of you actually seen a hunting season derailed by scope tracking, or is this more "insurance against what could happen"?

For OP specifically: if low light is your real constraint, Mark 5HD. If you're doing a lot of field adjustments in mixed conditions, SHV. Test mount both if you can—sarah.b's right that eye feel is shooter-specific.