If you want to get the facts on what the Military used, checkout the following site, and pull up the specifications I have listed.
http://assist.daps.dla.mil/online/start/, go to “Quick search” If you read in the book “M1 Garand to M14 Rifle”, you will find that the military had a problem with the Garand seizing in wet weather. So the military purchased commercial greases, conducted a rain test on them, and found that Lubriplate 130 was the most acceptable commercial grease. I think animal fat was actually the best of them all! Then they wrote a performance specification around the material properties of Lubriplate 130. Anyone who could make a grease that passed the tests outlined in Mil-G-46003 was able to sell it as Rifle Grease to the Military.
What you find is that Military Rifle Grease is basically a NLGI 3 water resistant bearing grease. I do not see any reason why a good grade of Marine Wheel Bearing grease would not work equally as well.
Rifle grease is meant for a hot wet environment. And is not meant to be used in temperatures less than 32 F.
I really like LSA as an all weather overall lubricant. VV-L-800 also is a good lubricating oil for rifles if you read the specification.
As for commercial oils, I have used synthetic Mobil 1 5W-30 Motor oil for decades as a lubricant. Just rub it in on an oily patch. .
I think the easiest advice to follow, that I was given as a novice, for M1/M14’s was to use LSA in the winter and rifle grease in the summer. But as long as you use an oil in the winter, and a grease in the summer, your Garand will not have any lubrication problems.