I was in the Marine Corps and while I'd love to maintain the myth that every Marine is some kind of superhero marksman, that is simply not the case.
Two weeks of boot camp is dedicated to the rifle range. One week of "snapping in" in which you practice endlessly in the standing, kneeling, sitting and prone positions while learning about windage, breathing techniques and trigger control, etc.
The second week you are out on the range firing hundreds of rounds of live ammunition. When it comes time to qualify, it is almost impossible to not make at least marksman (sharpshooter and expert are even higher ratings), especially with friendly co-recruits pulling butts for you and spotting your rounds on the targets at the other end. We made sure every recruit at least got marksman.
There are many ways to wash out of boot camp but I can't remember a single instance of a recruit washing out at the rifle range.
Now most Marines do have more than decent shooting skills and can probably field-strip and clean an M16A1 while blindfolded but by and large they are not much better shots than your typical farm kid who grew up with rifles. To be a sniper, you need years of practice with tens of thousands of rounds. I don't think Oswald was of that caliber (pun intended).
My brother never fired a weapon in his life. After OCS at Quantico he could put a a squirrels eye out from a thousand yards(exaggeration here but I think you get my drift).
I never said Oswald was a sniper, just that he certainly
became a Marine. He didn’t wash out. And he was crafty enough to buy the Italian carbine through the mail most likely so some Texas gun dealer wouldn’t be able to say “I sold that guy a Mannlicher Carcano rifle!’’ Again, I don’t buy the conspiracy bit anymore. People talk.
And something like being part of a plot to kill the
President of The United States would make you a liability to someone high up the DC food chain You could even end up dead yourself if you knew too much.