In fact I read before he was a terrible shot and basicly got booted out of the Marines.... And his fellow soldiers laughed at what an incredibly bad shot he was. He was said to be by far the worst shot in his Company."
The USMC marksmanship standards have been the same since before WWI. Recruits initially qualify in Boot Camp, and Fleet Marines qualify yearly after that. The ranking structure is 'Expert', 'Sharpshooter', and 'Marksman' in that order from top to bottom. Out of a training company, as many as a dozen or more green recruits will go 'Unk' and have to requalify at the range as basic marksmen.
Oswald's service jacket shows that he qualified two points above the minimum for sharpshooter (in Recruit Training Regisment at MCRD Parris Island) on one occasion and only one point above the minimum requirement for marksman about a year later. Oswald never went 'Unk', or 'Unqualified' in his career.
Only one fellow Marine named Delgado appeared in front of the Warren Commission to testify that he was near Oswald on the range when he scored poorly. Delgado did testify that he believed that the FBI pressured him to change his story, but another Marine who served with both Delgado and Oswald insisted that Delgado was full of crap.
Having been a Marine, I can tell you that Oswald sounds like a typical rifleman, and I've also had bad qualification days. I currently shoot higher scores on the same exercise in NRA High Power competitions than what the high-end cutoff score is for USMC 'Expert'. There's 'Master' and 'Grand Master' above that level, but the US Marine Corps doesn't rate shooters any higher than 'Expert'.
Oswald was a capable shooter, and intimately familiar with the rifle he owned -- that's my opinion.
The shot was not difficult for Oswald's skills, and conspiracy theorists have been claiming otherwise for decades. Almost every conspiracy theory hinges on dismissing Oswald as the primary shooter.
Oswald didn't have to use a iron peep sight
with a mean ass DI hovering over him when he shot JFK.
(Yes, shooting the President would be less stress than those Smokey Bears put on recruits)
Instead he used a bolt action scooped rifle at relative close range.
Doesn't take a sniper to do that.