Sutro - Your understanding about the Russian effort to determine the most effective cartridge is the generally accepted explanation, and no doubt correct.
Marines are not your average infantryman. To a Marine, shooting is a way of life; EVERY Marine is a rifleman, and EVERY Marine, including the Commandant of the Marine Corps, has to qualify at least once every year (in peacetime), and everyday in combat. It was out to 500 yards, and now to 600 meters (656 yards)
In Korea, may GOD BLESS ALL OF THOSE MEN WHO FOUGHT THERE!!! The 1st Marine Division went into the Chosen Reservoir with about 14,000 Marines, including some small U. S. Army Units, some British Royal Marines, some Greeks, Some Turks, and a few nondescript others, and due to the weather, sporadic air support. A Marine Division of the time was made up of about 19,000 when at full strength.
We, 14,000 men were surrounded by 8 ChiCom Divisions, and they had 12 ChiCom Divisions in Reserve, at the start of the Chosen Reservoir battle, there were somewhere around 160,000 Chinese Regular Professional Soldiers. We had to fight for our lives, and proceeded to walk out through some of the most terrible conditions, including constant enemy fire of those ChiCom Soldiers. When we reached Hungnam, the ChiCom Divisions had been reduced to the fact that several of their Divisions no longer existed, and ALL of them had been severely reduced in numbers. After that, it was the Washington D.C. Politicians who kept us from finishing what had been started.
The SKS was used, but not in large numbers, it was very effective in close. We could and did pick them off with our Garands beyond their effective range quite readily. If the Politicians in Washington D.C. had supported the troops in Korea as they had supported the troops in WWII, there would be no North Korea, there would be only one Korea, and we may have had to take on the ChiComs, on their home territory, in the process. Once we went into Korea, the ChiComs were really afraid we might just go into China and Kick the Communists out.
As to Viet Nam, may GOD BLESS ALL OF THOSE MEN WHO FOUGHT THERE TOO!!! It was again a case of the Politicians failing to support those they so freely sent into harms way. The soldiers, sailors, and Marines never lost a battle in Viet Nam, they lost everything in Washington D.C. None of the Politicians who caused so much misery should be able to hold his/her head upright.
I have to add this: I don't trust McCain, keep in mind he was quite thoroughly brainwashed by the NVA, while a POW, and I believe it shows.