Here’s what doesn’t make sense to me. If you look at comparable scopes, the Mark 4 doesn’t seem to lack in features or quality of glass compared to the Mark 5. However, if you compare models with similar magnification and reticles the difference in price is significant.
Mark 4HD 4.5-18x52
Ready your rifles with a versatile Mark 4HD. We took the legendary performance of its predecessors and gave it a slimmer maintube that’s been packed full of professional-grade features. Whether you’re a dedicated enthusiast or a seasoned expert, the Mark 4HD’s optical clarity and lightweight...
www.leupold.com
Mark 5HD 3.6-18x44
Pick up a Mark 5HD™ 3.6-18x44mm and you'll feel the difference. It's up to 20 ounces lighter than other riflescopes in its class, giving you an advantage in the field or at the range. The versatile 3.6-18x magnification range helps you engage close targets, while also giving you the flexibility...
www.leupold.com
Both have an Illuminated PR1-Mil reticle. What makes the Mark 5hd $900 better?
A late reply, but I will repeat what the Leupold Rep at the Hillsboro Hunt Expo told me in response to my question about price, build, function and quality differences between the 5HD and 4HD a few weeks ago (March 2025):
The Mark 4HD is a newer design that was not limited by the military specs that the 5HD was built around. However, the "rear half" of the two scopes are identical (or nearly so) and share the same components. The rep explained that the ability to use prior RD & Parts in the rear half of the scope enabled them to cut the price. I have no idea what the sales volume assumptions are/were for the Military contract and non-military sales of the 5HD vs. the 4HD, so it is difficult to back check the argument. As a retired finance executive, I lean towards calling "BS" on the pricing rationale. I suspect that it is just as likely that Leupold felt they needed to hit a lower price point on the FHD in order to justify the price point for the 5HD.
Many (all?) of the 4HD scopes have a longer front bell which was not an option under the military contract specs. The longer front bell enables some advantages in terms of internal angles that result in a better viewing experience that is easier on the eye, among other things. Who knows, maybe it also uses fewer lens elements and that helps keep the price down.
One rep said he favors the 4HD for competition because it is easier on his eyes the other rep who also shoots competition and I believe is ex-military said he prefers the 5HD (In both cases we were discussing lower magnification versions for hunting in mixed conditions) and his primary reason was that when shooting competition he values the lower "Low End" magnification and wider field of view at the low end over the slightly better viewing experience of the 4HD.
Lastly, the Rep (all the Reps in the booth) insisted that there was absolutely no difference in reliability between any of the 4, 5, or 6 HD scopes. I think I asked if there was anything different in the construction that would suggest that there might be a future reliability difference. If I did ask that question they said "NO".
Next, I asked if they were aware of the Rockslide / Form "drop" test and all the "blowback" Leupold was getting from Rockslide members as a result of that. The answer was "Yes" and "we are reaching out to them to discuss...". I asked how do they justify their argument of reliability given the Rockslide drop test. They answered with the standard Leupold response which focused on their internal testing protocols (which might not relate at all to falling on a scree slope, or dropping your rifle on a rock, etc.)
This particular rep has been with Leupold a long time, I think he is a regional level manager, he shoots competitions in the PNW and from time to time takes turns doing the "test shooting" of scopes that have come back to Leupold due to owners reporting issues, such as failure to hold zero. He seemed honest, sincere and believable. Both guys at the booth shoot competition and sometimes take turns doing scope warranty trouble shooting. They both claimed that scopes that are returned for issues with RTZ or similar almost never fail the Leupold tests. So infrequently that it is a big deal and a surprise when they do. They did not give specific frequency but the impression was that it was at least days of testing "suspect scopes returned for warranty" between finding an actual bad scope. The implication is that most scopes suspected of having an issue actually have an "attachment" problem or an operator problem.