I'm still puzzled by the decision to adopt an SPR style rifle as the main DMR after they first started with the Type 88 under that absurd "5.8 will do everything" idea
It’s not that much of a shocker really.
first not everyone in NATO or the rest of the world has abandoned the SPR concept. The USMC M27 is a “will do everything” rifle in example. During the GWOT a number of countries retained the 5.56x45mm SPR with selective issue of 7.62x51mm DMRs.
like all things it has a pros and cons.
From a logistics standpoint a SPR means a common cartridge across your infantry units. So if your unit is on the unfortunate end of an encirclement battle, something we have seen in Ukraine.
What ammunition you have can be distributed across your unit. Where a dedicated DMR is likely the odd man out who has to trade his specialist tool for a regular rifle loosing the advantage of that tool. If that encircled unit gets resupply likely by drone having a common cartridge means that you have more overall ammunition per drone than you would if you were specializing. Even if you loose multiple resupply drones what gets through can be used more broadly.
Your regular Riflemen can use the same ammo as your Machine Gunner, your DMR guy can use the same ammunition as your regular riflemen. It also makes transition easier between weapons. As the controls recoil and manual of arms are all but identical. Where a specialist weapon like the old QBU 88 would require retraining. Now generally it’s not that much of a hurdle a day and a half might do for transition but what you really want is to get that new DMR guy on the range not the class room.
The Cons are however that you are operating within the limitations of the standard cartridge.
Intermediate caliber cartridges are generally not meant for use at extreme ranges. They generally make a trade of energy resulting in either loss of stability or loss of penetration over distances. So well a 5.56x45mm at a 1000m is possible at that point the cartridge is basically falling from the sky. It’s got very little penetration and is given to wind and other factors.
Now the Chinese claim the 5.8x42mm is better at maintaining energy and it probably is. There are a number of 6mm cartridges that have better performance vs S109 after all. Still at extended ranges they make similar trades and against hard cover at close ranges they tend to be pulverized at extreme ranges they have nothing behind them.