Doctor Evil wrote:

More stuff he knows little about.

I understand that he consistently denied doing it himself....

He probably would though. It's a technique that is called 'lying'.

Does that mean he let off 3 round with a sub standard bolt action rifle

Pre-WW2 many armies trained on 1000 yard ranges and the average
squaddie was expected to score hits at that range, using the standard
iron sights. Oswald's rifle had a telescopic sight. Post-WW2 rifle
accuracy was generally sacrificed in the interests of rate-of-fire.
Many old bolt action rifles are accurate; they have long barrels. I
don't know how knackered Oswald's army-surplus one was.

hanging out of a windows and had two hits?

No, from inside the building, in the shadows and with the weapon on a
rest built from boxes of books.

I understood (and I can't be bothered to check) that he'd trained as a
sniper whilst in the USMC. A mediocre shot could achieve hits at the
ranges involved. I think it was below 200 metres and again I would
check if I had any interest in this topic; I haven't.

The man on the floor below heard the action being operated and the
spent cartridges falling on the floor above his head. A BBC programme
had a 3D computer model which showed the 'magic bullet theory' was
simple ballistic fact. As to the rate of fire, the ballistics
consultant demonstrated that 3 aimed shots could be easily discharged
in the time achieved by the gunman/gunmen/Oswald.

around the grassy knoll as that is where they heard some shots come from.

Where they thought they'd heard the shots coming from. It's difficult
to locate the source of high-velocity gunfire in a built-up area. There
are 2 separate sounds (crack from projectile, followed by thud from
firing position) and they both echo off buildings.

There's no great doubt as to what happened. The conspiracy theory has
been greatly embroidered to be re-sold to the credulous. JFK DVD
anyone? And can I also interest you in a magnetic water conditioner?