Some Ballistics questions

[John Dolva]

Could someone review and comment please?

My understanding is that a rifles barrel is angled up slightly and the scope is zeroed so that when the bullet drops back to the scope line hopefully a strike is made.

-is the barrel itself at an angle or is the bore drilled at an angle into the barrel. or both?

If the rifle is tilted as per image, is my assumption that the zeroing is thrown out the window measurable by some pre-existing formula? How likely is this as a factor over the range?

On a rifle with a scope that according to reports needed to be shimmied has this been discussed? Can anyone provide links? Also from someone with expertise what would be the correct terminologies to use in discussing/researching this?

Edited November 2, 2005 by John Dolva

[Pat Speer]

John, I'm by no means an authority on this topic but I have read a bit, and I can tell you that sights on rifles are indeed set up to account for a certain amount of bullet drop. I believe it varies from rifle to rifle. Something tells me it's set for something like 200 yards when fired parallel to the ground. Al Carrier and Ryan Crowe would probably know the exact specs on a rifle like Oswald's, if that's what you're looking for.

[John Dolva]

John, I'm by no means an authority on this topic but I have read a bit, and I can tell you that sights on rifles are indeed set up to account for a certain amount of bullet drop. I believe it varies from rifle to rifle. Something tells me it's set for something like 200 yards when fired parallel to the ground. Al Carrier and Ryan Crowe would probably know the exact specs on a rifle like Oswald's, if that's what you're looking for.

Thank you, Pat. Yes good specs is what I'm after. Well as good as is available. I understand that at some point there were shims added to the scope and I'd like to know which good photos are the earliest. Also exact angle of scope/bore. As well the above post. In the second image the second rifle is tilted to the right so I'm suggesting that the drop will be off to the right. In other words a tilt could send a bullet sighted on Kennedy , into Connally.

[Mark Knight]

While I'm no expert on ballistics, I do some hunting, and I learned a little science on my way through school. The simple explanation in order to answer your question is to go back to basic high school physics class. My last day there was over 33 years ago, so I might be a little rusty on this. After a bullet leaves the muzzle of a firearm, the downward acceleration of gravity begins acting upon the bullet, at a rate of 32 feet per second, per second. To compensate for the effect of gravity, the barrel of a firearm is angled slightly upward, when the firearm is held at or near a position with the sights perpendicular to the horizon. A gun sight, whether an iron sight or a telescopic sight ("scope"), is sighted in for accuracy at a particular distance.

The trajectory of the bullet will thus rise, in relation to the point of aim, and then fall. The goal is to coincide the point of aim and the point of impact. Unless a particular bullet exhibits an unusually flat trajectory (relatively flat, as a truly flat trajectory is a physical impossibility in weapons as we know them), decreasing the distance between the gun and the target--without a corresponding change in the sights--will result in a shot hitting "high," and increasing the distance will result in a shot hitting low.

Tilting the gun to the right changes where the gun will shoot in relation to the target. The "rise" in trajectory will now be to the right, but the effect of gravity will remain downward...the net result being that the "rise" in trajectory, which is now angled to the right, no longer uses gravity as a correction factor...and in theory, at least, the shot will skew to the right considerably more than anticipated by the shooter. So I suppose that fact alone supports the idea of an "accidental" hit on Connally.

But as a hunter, I must say that there is a great deal of difficulty involved in firing a gun in the manner suggested...in my experience, the alignment of the human body makes this feat a lot harder than it looks, to "rotate" the gun more than just a few degrees to the right or left, especially while standing upright. But it's still within the realm of the possible.

[Al Carrier]

While I'm no expert on ballistics, I do some hunting, and I learned a little science on my way through school. The simple explanation in order to answer your question is to go back to basic high school physics class. My last day there was over 33 years ago, so I might be a little rusty on this. After a bullet leaves the muzzle of a firearm, the downward acceleration of gravity begins acting upon the bullet, at a rate of 32 feet per second, per second. To compensate for the effect of gravity, the barrel of a firearm is angled slightly upward, when the firearm is held at or near a position with the sights perpendicular to the horizon. A gun sight, whether an iron sight or a telescopic sight ("scope"), is sighted in for accuracy at a particular distance.

The trajectory of the bullet will thus rise, in relation to the point of aim, and then fall. The goal is to coincide the point of aim and the point of impact. Unless a particular bullet exhibits an unusually flat trajectory (relatively flat, as a truly flat trajectory is a physical impossibility in weapons as we know them), decreasing the distance between the gun and the target--without a corresponding change in the sights--will result in a shot hitting "high," and increasing the distance will result in a shot hitting low.

Tilting the gun to the right changes where the gun will shoot in relation to the target. The "rise" in trajectory will now be to the right, but the effect of gravity will remain downward...the net result being that the "rise" in trajectory, which is now angled to the right, no longer uses gravity as a correction factor...and in theory, at least, the shot will skew to the right considerably more than anticipated by the shooter. So I suppose that fact alone supports the idea of an "accidental" hit on Connally.

But as a hunter, I must say that there is a great deal of difficulty involved in firing a gun in the manner suggested...in my experience, the alignment of the human body makes this feat a lot harder than it looks, to "rotate" the gun more than just a few degrees to the right or left, especially while standing upright. But it's still within the realm of the possible.

John,

Mark has explained this as well as anyone can. My hat is off to him on not only his understanding of this, but his ability to explain it in layman's terms.

Most rifles are factory sighted by bore sighting at 100 yds, which Mark is explaining on barrel tilt that makes the factory adjustment of rise and fall in elevation through initial trajectory gain and loss. Optical sights are sighting generally at 200 meters (if available) in a caliber consistent with the MC. This sighting is done with a level elevation target. In the feat of the supposed Oswald shot, he would have to take into account the formula of lack of gravitational pull from the optical sighting. If this was not figured into the shot, the bullet strike would be in the range of +12". The shooter would also have to be versed in leading and compensating a moving target at the speed of the limo at this range which would put it in the range of a +2 minute of angle and nearly as much in negative elevation.

Al

[Pat Speer]

I seem to remember reading where some of the top snipers were so expert in anticipating bullet drop over distance that they could hit targets that they technically could not see (such as an enemy sniper laying on a hilltop just out of sight). FWIW

[Mark Knight]

Al, thanks for the compliment. My brain hasn't quite turned to mush just yet, and I appreciate your expansion on my words. Since I'm hoping soon to embark on a new career in teaching, it's nice to hear that my explanation was both correct and expressed in layman's terms.

And Pat, I have personally witnessed some feats with a shotgun firing deerslugs that, had I not seen them myself, I would've said they were impossible, both in range and accuracy. But my Dad got to know his 16-gauge Browning semiautomatic [pre-"Sweet Sixteen" vintage] pretty well over 40 years. And I'm sure that military-trained snipers and sharpshooters could do even better. With firearms, familiarity breeds...accuracy.

[John Dolva]

While I'm no expert on ballistics, I do some hunting, and I learned a little science on my way through school. The simple explanation in order to answer your question is to go back to basic high school physics class. My last day there was over 33 years ago, so I might be a little rusty on this. After a bullet leaves the muzzle of a firearm, the downward acceleration of gravity begins acting upon the bullet, at a rate of 32 feet per second, per second. To compensate for the effect of gravity, the barrel of a firearm is angled slightly upward, when the firearm is held at or near a position with the sights perpendicular to the horizon. A gun sight, whether an iron sight or a telescopic sight ("scope"), is sighted in for accuracy at a particular distance.

The trajectory of the bullet will thus rise, in relation to the point of aim, and then fall. The goal is to coincide the point of aim and the point of impact. Unless a particular bullet exhibits an unusually flat trajectory (relatively flat, as a truly flat trajectory is a physical impossibility in weapons as we know them), decreasing the distance between the gun and the target--without a corresponding change in the sights--will result in a shot hitting "high," and increasing the distance will result in a shot hitting low.

Tilting the gun to the right changes where the gun will shoot in relation to the target. The "rise" in trajectory will now be to the right, but the effect of gravity will remain downward...the net result being that the "rise" in trajectory, which is now angled to the right, no longer uses gravity as a correction factor...and in theory, at least, the shot will skew to the right considerably more than anticipated by the shooter. So I suppose that fact alone supports the idea of an "accidental" hit on Connally.

But as a hunter, I must say that there is a great deal of difficulty involved in firing a gun in the manner suggested...in my experience, the alignment of the human body makes this feat a lot harder than it looks, to "rotate" the gun more than just a few degrees to the right or left, especially while standing upright. But it's still within the realm of the possible.

John,

Mark has explained this as well as anyone can. My hat is off to him on not only his understanding of this, but his ability to explain it in layman's terms.

Most rifles are factory sighted by bore sighting at 100 yds, which Mark is explaining on barrel tilt that makes the factory adjustment of rise and fall in elevation through initial trajectory gain and loss. Optical sights are sighting generally at 200 meters (if available) in a caliber consistent with the MC. This sighting is done with a level elevation target. In the feat of the supposed Oswald shot, he would have to take into account the formula of lack of gravitational pull from the optical sighting. If this was not figured into the shot, the bullet strike would be in the range of +12". The shooter would also have to be versed in leading and compensating a moving target at the speed of the limo at this range which would put it in the range of a +2 minute of angle and nearly as much in negative elevation.

Al

(remembering of course here we are talking about the MC as presented in evidence)

Mark, Al, and Pat, thanks. That gives me key words and concepts to go on. Not sure I understand exactly. But using the right words helps. Al, I take it you agree that a tilt as I described is unlikey? It seems to me that a slight tilt could cause a wide error as not only is the bullet not curving back into the line of sight, it also wouldn't rise as high? Also for clarification is the upwards slope of the bore in the barrel being sloped or is the bor in the barrel sloped? (sorry about all the questions, use of correct words will halp me to find out for myself, a good link would be good)

Also could a look be had at these and comment (with pipe, angle, boxes etc on whether sufficient room is available, and whether if it is tight, would that mean a greater chance of tilting the rifle?

There has been speculation of a left handed shooter from this location. I'm not a shooter (except arcade) hence ignorance. Does a left handed shooter encounter different room problems? Would a tilt to the left be more likely (please look at the above pic to see what I mean re tilt) The very first pic up top shows a tilt to the left which I would assume a right handed shooter might do in a tight spot?

(in the lower left pic I've estimated the location of the pipes behind the boxes. Does anyone have a picture that shows the floor with pipe locations?)

.

Edited November 2, 2005 by John Dolva

[Mark Knight]

The bore of the barrel SHOULD be a straight line; the upward angle of trajectory is created by the positioning of the barrel itself. To introduce curvature into the bore of the barrel would impart a frictional element that would tend to destabilize a bullet in flight...and it's my understanding that the rifling in a barrel, which imparts spin to the bullet to improve stability, would instead magnify the problems that a curved bore would impart to bullet accuracy and stability. So the barrel and its bore must be straight.

The problem I have with the idea of a left-handed shooter is in the design of the MC rifle. A left-handed shooter would hold the rifle against his left shoulder, the left hand on the trigger and the right hand on the forearm portion of the rifle stock. If the gun exhibited any discernable recoil, there's a great likelihood that the bolt of the rifle would contact the shooter in the face, potentially causing injury. And if it's difficult for a right-handed shooter to get off three rounds in the allotted time with the MC, imagine the impossiblilty of a LEFT-handed shooter operating a RIGHT-handed bolt action.

Now, if you introduce a left-handed rifle into the equation--or even a semiautomatic rather than a bolt action rifle, the question of a left-handed shooter then looks a bit different.

[John Dolva]

Mark, I worded this very poorly : " Also for clarification is the upwards slope of the bore in the barrel being sloped or is the bore in the barrel sloped?". I'm not suggesting a curve in the bore.

Is the upward slope in the barrel because the barrel itself is mounted pointing upwards OR is the barrel level and the bore in the barrel on an angle? Or both? (on the MC).

I agree, I find with the MC a left hander seems awkward.

The other questions:

Al, I take it you agree that a tilt as I described is unlikey? It seems to me that a slight tilt could cause a wide error as not only is the bullet not curving back into the line of sight, it also wouldn't rise as high? (sorry about all the questions, use of correct words will halp me to find out for myself, a good link would be good)

Also could a look be had at these and comment (with pipe, angle, boxes etc on whether sufficient room is available, and whether if it is tight, would that mean a greater chance of tilting the rifle?

(in the lower left pic I've estimated the location of the pipes behind the boxes. Does anyone have a picture that shows the floor with pipe locations?)

Edited November 2, 2005 by John Dolva

[Mark Knight]

I believe that the bore in a rifle barrel is concentric with the barrel. I'm not sure, but I believe that this is so that there are no "hot spots"where the metal is thinner and more prone to damage or fatigue after firing multiple rounds. I have seen barrels that taper from the breech to the muzzle, but they usually exhibit a uniform thickness at a particular circumference...exceptions being for mounting lugs and such.

To further clarify, compensation for the upward part of the trajectory is accomplished by raising the rear sight, or the rear portion of the scope, slightly. [Most modern scopes have adjustments for windage and elevation on the scopes themselves, but that's a separate issue.] But the barrel itself is mounted "straight", and it's the sight that is adjusted to compensate.

Beyond this point, you're pushing the limits of my firearms knowledge.

Edited November 2, 2005 by Mark Knight

[Thomas H. Purvis]

I believe that the bore in a rifle barrel is concentric with the barrel. I'm not sure, but I believe that this is so that there are no "hot spots"where the metal is thinner and more prone to damage or fatigue after firing multiple rounds. I have seen barrels that taper from the breech to the muzzle, but they usually exhibit a uniform thickness at a particular circumference...exceptions being for mounting lugs and such.

To further clarify, compensation for the upward part of the trajectory is accomplished by raising the rear sight, or the rear portion of the scope, slightly. [Most modern scopes have adjustments for windage and elevation on the scopes themselves, but that's a separate issue.] But the barrel itself is mounted "straight", and it's the sight that is adjusted to compensate.

Beyond this point, you're pushing the limits of my firearms knowledge.

Mark;

The "thicker" barrel at the chamber end serves multiple purposes.

1. Of course, this allows for the machining down of the breech end of the barrel for threads which thus allow the barrel to be screwed into the receiver/frame of the weapon, and still maintain barrel integrity.

2. The "chamber pressure" is greatest at the breech end where initial ignition of the propellant must create the chamber pressure necessary to begin to drive the bullet/projectile forward into the rifling of the weapon.

Once the projectile begins movement, chamber and barrel pressure begin to decrease with the advancing movement of the projectile.

Barrel thickness/outside diamater must also contain the functional co-efficient for adequate cooling of the metal between rounds fired at the maximum sustained rate of fire for the weapon.

All of which is based upon the grade/type, strength, expansion, contraction, and heat dissipation capability of the specific steel utilized in manufacture.

Tom

[Mark Knight]

Tom, I was aware of the points you mention. but when you get into such terminology as "headspacing" and the like, my understanding becomes a bit cloudy.

Having fired deerslugs through my dad's old Browing 16-gauge semiauto, I'm aware of the heat generated upon ignition, and the amount transferred through the barrel itself, by squeezing off a full 5-round magazine as quickly as one can keep the target acquired (probably 2 to 2-1/2 seconds total elapsed time).

And I can guesstimate the effect of larger magazines and large-caliber, higher-velocity ammunition (I've heard of 'water-cooled 50 calibers' somewhere down the line, possibly in a WWII context).

But you provide a great note of clarification for those who might not have had the opportunity to witness what I have seen, or who may have witnessed something similar without giving it much thought. Thanks for the added info.

[Gerry Hemming]

I believe that the bore in a rifle barrel is concentric with the barrel. I'm not sure, but I believe that this is so that there are no "hot spots"where the metal is thinner and more prone to damage or fatigue after firing multiple rounds. I have seen barrels that taper from the breech to the muzzle, but they usually exhibit a uniform thickness at a particular circumference...exceptions being for mounting lugs and such.

To further clarify, compensation for the upward part of the trajectory is accomplished by raising the rear sight, or the rear portion of the scope, slightly. [Most modern scopes have adjustments for windage and elevation on the scopes themselves, but that's a separate issue.] But the barrel itself is mounted "straight", and it's the sight that is adjusted to compensate.

Beyond this point, you're pushing the limits of my firearms knowledge.

Mark;

The "thicker" barrel at the chamber end serves multiple purposes.

1. Of course, this allows for the machining down of the breech end of the barrel for threads which thus allow the barrel to be screwed into the receiver/frame of the weapon, and still maintain barrel integrity.

2. The "chamber pressure" is greatest at the breech end where initial ignition of the propellant must create the chamber pressure necessary to begin to drive the bullet/projectile forward into the rifling of the weapon.

Once the projectile begins movement, chamber and barrel pressure begin to decrease with the advancing movement of the projectile.

Barrel thickness/outside diamater must also contain the functional co-efficient for adequate cooling of the metal between rounds fired at the maximum sustained rate of fire for the weapon.

All of which is based upon the grade/type, strength, expansion, contraction, and heat dissipation capability of the specific steel utilized in manufacture.

Tom

----------------------------

Tom:

If I might add: When we finished the shooting of "JFK", Hargraves and I went over to Frederick, MD to once again visit with Harold Weisberg. He had a somewhat different version of the M/Carcano in his "Office", and this one didn't have a scope attached. After getting past his disagreements with Oliver Stone, I went into the fact that our movie armorer had to cut the very strong bolt spring in half, in order that Gary Oldman, Kostner, and Sanders might work the action rapidly.

This seemed to astound him, and I looked at his wife -- seeking a response if we were over-taxing his waning energies -- but she nodded OK. I further explained to Harold that said mainspring is so strong that, with the action cocking upon opening the bolt [as opposed to the British SMLE Enfield, which cocks upon bolt closing, making it one of the fastest bolt actions made] causes the shoulder stock to be rotated out of the shoulder position. This Mauser type action, though much more fluid in the Wehrmacht's "Kar-98" in use throughout WWII, on rare occasions required use of the sling -- especially for 1,000 metre shots.

The Japanese Arisaka "Meiji-38" used the "Mauser" straight shank [WWI issue] bolt, and it too would sometimes cause the weapon to be pulled from the shoulder. So, Harold said: "....What you are telling me is that LHO would have had to return the shoulder-stock back into his shoulder the first time he reloaded...and this would cause how much interval between shots...?" I told him that Stone had sent the whole crew down to the rifle range the first week in Dallas, where we fired live rounds in a dozen different models/brands of rifles and carbines. Everybody lost the shoulder seating upon "cranking", and this required more time to reacquire the target using the scope. So we switched to not using the scope, and instead used the "iron-sights" -- but, without a "PROPER" leather sling, shoulder seat was lost every time.

Further, I explained that in order to aquire/re-aquire a target with the alleged LHO scope, the shooter's eye had to be within a half inch of the rear of the scope; thus due to heavy recoil: the shooter gets a "black eye" !!

Moreover, I mentioned that when Stone had rented the "6th Floor Museum" for 3 hours of our use, I had pointed out to Bob Groden that: with the bottom of the window-sill just 7+ inches above the floor, that a shooter [with LHO's upper torso measurements] would have great difficulty "hunching-down" so as to shoot through the window -- which only opened to the half-way point. I further pointed out that the FBI re-enactment photos show that the man holding the rifle is practically a midget, which you can verify with comparative measurement of the M/Carcano versus his upper torso.

BTW: A Silencer/Suppresor will leak smoke even after the first shot, due to an accumulation of gases within the tube, which acts to both give more accuracy & range [more burning of powder] and reduces the noise level.

Rice Krispies !!

Gerry

___________________________________

[John Dolva]

I believe that the bore in a rifle barrel is concentric with the barrel. I'm not sure, but I believe that this is so that there are no "hot spots"where the metal is thinner and more prone to damage or fatigue after firing multiple rounds. I have seen barrels that taper from the breech to the muzzle, but they usually exhibit a uniform thickness at a particular circumference...exceptions being for mounting lugs and such.

To further clarify, compensation for the upward part of the trajectory is accomplished by raising the rear sight, or the rear portion of the scope, slightly. [Most modern scopes have adjustments for windage and elevation on the scopes themselves, but that's a separate issue.] But the barrel itself is mounted "straight", and it's the sight that is adjusted to compensate.

Beyond this point, you're pushing the limits of my firearms knowledge.

Mark;

The "thicker" barrel at the chamber end serves multiple purposes.

1. Of course, this allows for the machining down of the breech end of the barrel for threads which thus allow the barrel to be screwed into the receiver/frame of the weapon, and still maintain barrel integrity.

2. The "chamber pressure" is greatest at the breech end where initial ignition of the propellant must create the chamber pressure necessary to begin to drive the bullet/projectile forward into the rifling of the weapon.

Once the projectile begins movement, chamber and barrel pressure begin to decrease with the advancing movement of the projectile.

Barrel thickness/outside diamater must also contain the functional co-efficient for adequate cooling of the metal between rounds fired at the maximum sustained rate of fire for the weapon.

All of which is based upon the grade/type, strength, expansion, contraction, and heat dissipation capability of the specific steel utilized in manufacture.

Tom

----------------------------

Tom:

If I might add: When we finished the shooting of "JFK", Hargraves and I went over to Frederick, MD to once again visit with Harold Weisberg. He had a somewhat different version of the M/Carcano in his "Office", and this one didn't have a scope attached. After getting past his disagreements with Oliver Stone, I went into the fact that our movie armorer had to cut the very strong bolt spring in half, in order that Gary Oldman, Kostner, and Sanders might work the action rapidly.

This seemed to astound him, and I looked at his wife -- seeking a response if we were over-taxing his waning energies -- but she nodded OK. I further explained to Harold that said mainspring is so strong that, with the action cocking upon opening the bolt [as opposed to the British SMLE Enfield, which cocks upon bolt closing, making it one of the fastest bolt actions made] causes the shoulder stock to be rotated out of the shoulder position. This Mauser type action, though much more fluid in the Wehrmacht's "Kar-98" in use throughout WWII, on rare occasions required use of the sling -- especially for 1,000 metre shots.

The Japanese Arisaka "Meiji-38" used the "Mauser" straight shank [WWI issue] bolt, and it too would sometimes cause the weapon to be pulled from the shoulder. So, Harold said: "....What you are telling me is that LHO would have had to return the shoulder-stock back into his shoulder the first time he reloaded...and this would cause how much interval between shots...?" I told him that Stone had sent the whole crew down to the rifle range the first week in Dallas, where we fired live rounds in a dozen different models/brands of rifles and carbines. Everybody lost the shoulder seating upon "cranking", and this required more time to reacquire the target using the scope. So we switched to not using the scope, and instead used the "iron-sights" -- but, without a "PROPER" leather sling, shoulder seat was lost every time.

Further, I explained that in order to aquire/re-aquire a target with the alleged LHO scope, the shooter's eye had to be within a half inch of the rear of the scope; thus due to heavy recoil: the shooter gets a "black eye" !!

Moreover, I mentioned that when Stone had rented the "6th Floor Museum" for 3 hours of our use, I had pointed out to Bob Groden that: with the bottom of the window-sill just 7+ inches above the floor, that a shooter [with LHO's upper torso measurements] would have great difficulty "hunching-down" so as to shoot through the window -- which only opened to the half-way point. I further pointed out that the FBI re-enactment photos show that the man holding the rifle is practically a midget, which you can verify with comparative measurement of the M/Carcano versus his upper torso.

BTW: A Silencer/Suppresor will leak smoke even after the first shot, due to an accumulation of gases within the tube, which acts to both give more accuracy & range [more burning of powder] and reduces the noise level.

Rice Krispies !!

Gerry

___________________________________

Gerry, right to the heart of the matter.

Would one assume that Oswald was aware of this stock shift? Is it something that comes with experience with a particular gun. Does the habit of someone as stated in evidence 'buried the gun near walkers place to retrieve later' indicate a knowledge of guns. How delicate exactly are sights. How 'lucky' was the seemingly perfect head shot? Is the pipe in the way for a comfortable shot?

Edited November 2, 2005 by John Dolva