You just have to look at the morality of the intent:
K98 was the spear-head of ethnic cleansing of Europe issued to Nazi forces to do the cleansing.
MN was issued to Russians defending USSR from invading Nazis.
Hypocrisy of the communists can not be overstated - they were murdering and enslaving bastards; the big difference that they were doing it under the flag of "what's best for the masses". Nazis did it under the flag of "what's best for us" - and it's hard to call 'em hypocritical. It is very easy to call Nazis and their ideology pure evil!
I agree that in the beginning of the war the 8mm cartridge took many Jewish lives. But the gas killed much more. I think the wartime K98 was produced not with the idea that "this will kill the jew" but more of "this will kill the allies" as our rifles were made with the idea that "this will kill the axis"
I believe both the Nazis in power and soviets in power were pure evil. But im not going to call their tools pure evil.