Those who don’t believe Oswald shot President Kennedy point out that his Mannlicher-Carcano was not a very accurate rifle.  It didn’t even have a sight-adjustment mechanism, no windage or elevation screws.  True so far.  That’s why Oswald made sure to purchase a four-power telescopic sight with the rifle.  That scope did have the necessary horizontal and vertical adjustment screws, so crucial for ensuring accuracy.  And he used them skillfully.

CE541(3), from page 124 of The Final Truth:

For those who might like a bit more convincing of the necessity of sighting-in/zeroing a rifle after re-assembly, 17 experts and gun manufacturers weigh in:
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it is difficult to reassemble so that the precision and accuracy of the firearm's shot group is maintained. This is because the component parts of the firearm do not re-seat in the same position that was occupied before disassembly, resulting in movement of the shot group placement and increases in shot group size. Thus, it is necessary to re-zero the rifle after reassembly.
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I frequently find I need to fine tune my zero from time to time on a number of guns, as I change ammo and bullet weights, weather conditions vary, or scope just gets knocked around during transport.

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Re-assembly:

1. Re install the bottom metal into the stock.
...
8. Go to the range and re-zero your rifle.
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The tracking of the average scope is not that repeatable. I have just gone through this, counting clicks from bottom, and on cheaper scopes, big changes in windage and elevation and ending back to zero, the point of impact is often very different at the end.

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Regardless of the cause, I find that handling changes zero on my rifles anyway.  It's always been a habit with me and the people I hunt with to zero along the way to a hunt.  There are so many things that change from one shooting day to the next.

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This means that you may need to check zero and/or re-zero your scope after you disassemble to this level. This is not an issue on the newer rifles.

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You will also have to re-zero your rifle after you are done.

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Since your rifle has iron sights or if you have installed an optical sight, re-zeroing is not a major issue because you can re-zero using these other sighting methods as your reference.

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I doubt any rifle out there truly holds an absolute zero when the barrel is pulled.

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No gun will keep absolute zero if you pull out the barrel.

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I'd yet to see a QD barrel system that doesnt require some zero tweaks if you pull the barrel off.

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I understand you need to re-zero a scope after removing and reinstalling the barrel/trigger assembly.

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Keep in mind that there's a chance a rifle will lose its zero at least a little bit after being put back together.

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given the time I spent zeroing scopes on fixed barrels which scopes could lose accuracy during transport, it required re-zeroing.
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I imagine the same applies to those which are portrayed in films as being assembled prior to the assassin taking his shot?

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...then if you have to re-zero after assembly, and weight is about the same. the take down feature is not all that important. other than initial transport to your camp

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Does anyone know of an actual sniper weapon which can be dismantled, including optic-site, without it losing its zero?

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The Final Truth: Solving the Mystery of the JFK Assassination

Paperback: http://www.amazon.com/gp/product/1490350578

Kindle: http://www.amazon.com/dp/B00CPSBM7U

Even the greenest marksman knows that a disassembled/reassembled rifle will never hold its zero [remain sighted-in].  This is common teaching even to beginning riflemen; Oswald was a Marine Corps-trained veteran marksman.  He knew he must re-zero with his first shot.

The Final Truth: Solving the Mystery of the JFK Assassination

Paperback: http://www.amazon.com/gp/product/1490350578
Kindle: http://www.amazon.com/dp/B00CPSBM7U
Website: http://www.thefinaltruth.net

From The Final Truth, pp. 121‒122:

“Sitting there in the sniper’s nest on the sixth floor, Oswald understood that it was not just temperature and humidity that could adversely affect his accuracy.  He had nothing short of disassembled his rifle, put it in a homemade paper bag, taken it to work in the back seat of a co-workers car, carried it up six floors and reassembled the thing.  Oswald knew as well as anyone in the State of Texas that if he didn’t first sight-in his weapon, he might as well not even bother squeezing the trigger.”

The Final Truth: Solving the Mystery of the JFK Assassination

Paperback: http://www.amazon.com/gp/product/1490350578
Kindle: http://www.amazon.com/dp/B00CPSBM7U
Website: http://www.thefinaltruth.net

The Final Truth: Solving the Mystery of the JFK Assassination also demonstrates that Oswald’s carbine was not sticking out of the window but remained entirely inside (p. 45).  The muzzle was stabilized on the far edge of the box resting on the windowsill.  This frame from the Secret Service film also shows that Oswald, in setting up the boxes for support, had planned from the outset to fire as the target was moving away on Elm Street, positioning himself to minimize the apparent movement of the target.

 

 

The Final Truth: Solving the Mystery of the JFK Assassination
Paperback: http://www.amazon.com/gp/product/1490350578
Kindle: http://www.amazon.com/dp/B00CPSBM7U