[Durus]

Military records indicate that Oswald was not a talented marksman, in fact he did quite poorly using a far superior rifle (m1 garand) to that of the carcano he is purported to have used during the assassination.

[wideawake]

Military records indicate that Oswald was not a talented marksman

Commonly claimed, but simply not true.

The records show that he was twice rated as sharpshooter and once as marksman.

a far superior rifle (m1 garand) to that of the carcano

According to the FBI's weapons expert who tested the Carcano, it was a highly accurate weapon.

Like all mass-produced weapons, the quality of a Garand and a Carcano can vary depending on where it was made and what conditions it has undergone since manufacture.

[oh8eleven]

Military records indicate that Oswald was not a talented marksman ...
Back in the 50s/60s, there were four ratings for Marine shooters: Expert, Sharpshooter, Marksman and "Unk" (Unqualified).
Oswald qualified as a Sharpshooter and later re-qualified at the lower rating of Marksman. Meaning, maybe not an "expert", but still good enough.
Qualification is done at three distances, 200, 300 and 500 yards (not feet), including slow and rapid fire. Look down this page for more details.