Any prevailing theories on the back wound?

[Gary Murr]

Hello Tom:

The Purvis "tumbling bullet theory" - an expression I don't believe that Tom Purvis ever actually used - contained many nuances. The one particular theoretical aspect that Tom was able to recreate - and I stress that his writings on this subject matter like everyone who dare enter this morass are/were theoretical - was that Tom fired 6.5mm MC bullets manufactured by the WCC from his MC weapon through individual "live" branches of Oak the makeup of which was identical to the TSBD intervening Oak tree that sits in Dealey Plaza. This is an Oak that does not shed its foliage as the season's pass, unlike other types of Oak tree. Tom retrieved these cartridges after their transit of the Oak limbs and photographed the results. If I can find them - and it is a big if because I have not been into these materials for a number of years - I will post the colour images I was sent. The bullets thus retrieved were slightly flattened along their axis and lead did protrude/extrude from the open base of the cartridges - the open base of this ammunition as well explained elsewhere in this thread by Bob Prudhomme. My own opinion, and it is only that as I am not now nor have never professed to me a ballistics expert, is that the main problem with any discussion, theoretical or otherwise, that deals with the transit of any cartridge through anatomical structures, human or animal, is that no one can predict precisely what a cartridge or potentially its fragmented offspring will do during transit of an anatomical structure. I do not doubt the sincerity nor the makeup of the various arguments being advanced in this thread, most of which have as their foundation well argued lines of clarity based upon sound reasoning and historically retrievable examples. There is much in this particular thread that is of great importance and anyone interested in attempting to better understand the importance of the issue of just what caused the back wound is wise to read and absorb what has been written - but do so with an open mind.

Gary

[Tom Neal]

The one particular theoretical aspect that Tom was able to recreate - Tom fired 6.5mm MC bullets manufactured by the WCC from his MC weapon through individual "live" branches of Oak the makeup of which was identical to the TSBD intervening Oak tree that sits in Dealey Plaza.

Tom retrieved these cartridges after their transit of the Oak limbs and photographed the results.

Hello Gary, thanks for you response.

Do you recall the approximate diameter of the branches used by TP? From the photos of DP I have no idea if they were 1"; 1/2"; 1/4" or whatever. It will be interesting to see how thick a branch was required to cause the type of damage to the bullet that you describe. The branch diameter would be necessary to estimate how much velocity was shed by the bullet during contact with a branch. Also, unless it was a hit at the exact center of the branch, the trajectory of the bullet would be altered. Did TP do any estimates of angles of deflection and velocity lost?

If I can find them - I will post the colour images I was sent.

I hope you can find them, and of course, thanks for looking!

The bullets thus retrieved were slightly flattened along their axis and lead did protrude/extrude from the open base of the cartridges - the

open base of this ammunition as well explained elsewhere in this thread by Bob Prudhomme.

The bullets were flattened on BOTH sides of the long axis every time, or sometimes only on ONE side? I agree with you - Bob P. did a fine job explaining the open base of this ammo, which was a surprise to me. I had taken the "F" in "FMJ" literally.

...no one can predict precisely what a cartridge or potentially its fragmented offspring will do during transit of an anatomical structure.

Ain't THAT the truth! It can't be said often enough. There are simply too many unknowns, and too many variables.

The best that can be hoped for is to separate REASONABLE theories into categories, such as probable, possible, and unlikely.

Tom

[Robert Prudhomme]

As an extension of the experiment shooting through live oak branches, it would be interesting to have a chronograph set up on the far side of the branch to measure the velocity of the bullet, once it had passed through the branch.

[Chris Davidson]

The only footage I have that tries to replicate.

https://spideroak.com/browse/share/JFKFILES/JFKVIDEOS

Password: assassination

chris

[Chris Davidson]

Tom's description:

[Tom Neal]

As an extension of the experiment shooting through live oak branches, it would be interesting to have a chronograph set up on the far side of the branch to measure the velocity of the bullet, once it had passed through the branch.

Absolutely, Bob!

From the previous thread on this back wound, I see three major questions here:

1. velocity of the bullet post tree limb encounter (this allows calculation of the impact velocity)

2. trajectory of the bullet post tree limb encounter (this determines point of impact)

3. could a 'deformed' bullet inflict the type of back wound reported? (length and diameter of Humes' little finger)

FWIW, my little finger is 3/4" in diameter at the 2nd knuckle, and from 2nd knuckle to the tip is 2". I am 6' tall with a medium build, and Humes was 6'4" with a large build.

Tumbling or not, 3/4" is rather a large hole for a Carcano bullet, isn't it?

Tom

[Tom Neal]

The only footage I have that tries to replicate.

The angled green line is exactly on the long axis of the moving bullet. From the point that the bullet exits the last branch until it disappears off screen, the bullet is at a 35 degree nose above the horizontal attitude and absolutely stable.

Chris,

Do you know the range of the shooter to the branches and to the target? In the dialog at the end of the clip it is stated that the bullet was deflected only about an inch from its intended course. He then says it would have continued on and hit the pavement. If it was only deflected an inch but would have hit the pavement, I have to wonder the distances they are using from rifle to branch, and branch to target.

Tom

[Chris Newton]

In the second image posted by Chris D. the statement that "Nobody could have accurately fired that rifle from the way they had it "jacked up" in the window".

I think that the way it was "jacked up" is a result of their gross negligence in obtaining the wrong type of tripod. I'm assuming he is referring to the camera/tripod/scope setup the FBI used.

I have the same type and size of 60's style tripod, (that was my father's) with the same type retractable aluminum legs and looking at a photo of their setup I get the impression that the tripod is at it's minimum height. If the window ledge had been at a normal height there would have been no problem. I can imagine the total SNAFU situation when they showed up to do the photographic re-enactment. One word: incompetence.

[Chris Davidson]

The only footage I have that tries to replicate.

The angled green line is exactly on the long axis of the moving bullet. From the point that the bullet exits the last branch until it disappears off screen, the bullet is at a 35 degree nose above the horizontal attitude and absolutely stable.

Chris,

Do you know the range of the shooter to the branches and to the target? In the dialog at the end of the clip it is stated that the bullet was deflected only about an inch from its intended course. He then says it would have continued on and hit the pavement. If it was only deflected an inch but would have hit the pavement, I have to wonder the distances they are using from rifle to branch, and branch to target.

Tom

Tom,

It's not specifically stated, but using their remarks from a different segment, my guess would be approx 25yds.

In another test, they measured the speed of the bullet at 2089ft per sec, 10ft past the muzzle.

That bullet went through 36 inches of pine wood at what looks to be the approx 25 yard marker.

chris

[Robert Prudhomme]

The only footage I have that tries to replicate.

https://spideroak.com/browse/share/JFKFILES/JFKVIDEOS

Password: assassination

chris

Shoot! I couldn't get the audio to work when I watched the video. Oh well, no matter.

When we were discussing branches, I was thinking about something a little more substantial than those "twigs" they had set up there. I seriously do not think passing through those little things is going to rob the bullet of 1700 fps. But what do I know, eh? I'll tell you one thing, though. That bullet had a serious yaw to it and had definitely not lost much of its original velocity. I wonder how many shots it took until they had one that wasn't tumbling?

Something else to think about. If Tom Purvis reported his bullets were flattened on one side (or both) but undamaged on the nose, he could not have been hitting the branches "nose on" with the bullets. A flattened bullet, with a pristine nose, is indicative of a bullet hitting something hard at an oblique or tangential angle (almost "side on" as we would say around here. A bullet hitting at this kind of angle is guaranteed to be tumbling, and way off its mark.

P.S.

Tom

Mark a point on the ground and run two lines out from it about 75 feet. A couple of inches out from the origin, separate the lines by an inch. Go out to the 75 foot mark and see how far apart the lines are.

[Robert Prudhomme]

Tom's description:

This is the kind of nonsense I was speaking of. According to Tom, if you shoot a rifle sighted in at 100 yards, any shot less than 100 yards will impact lower than the line of sight.

Crap!

Look at this diagram:

As can be seen, the line of sight (through the scope) is slightly higher than the tip of the barrel. Once the rifle is sighted in at the target, the barrel will be tilted up slightly, so that the bullet will follow a parabolic curve that crosses the line of sight first just a few feet out from the end of the barrel, and again at the target.

Anywhere in between these two crossing points, the bullet will be higher than the line of sight, and impact a target higher than what the shooter is aiming at. To hit a target at 50 yards, the shooter, if the rifle is sighted in at 100 yards, must aim slightly low on his target.

This is further exacerbated by the fact it was downhill from the 6th floor to the limo, and a bullet will always impact higher than the aiming point when shooting downhill (or uphill).

[Ron Ecker]

Given the planning that went into this assassination, including, I assume, the use of expert marksmen, I don't understand why one of the shooters would choose a position that required shooting through tree branches.

It's possible, I suppose, that they wanted the patsy shooting from the so-called sniper's nest, through tree branches if necessary, and didn't care whether he hit anything or not. But that would assume that Oswald actually fired a shot that day, which I seriously doubt. I would allow, however, that if one of the shooters did shoot through tree branches that day, it must have been Oswald. Who else?

[Tom Neal]

Tom

Mark a point on the ground and run two lines out from it about 75 feet. A couple of inches out from the origin, separate the lines by an inch. Go out to the 75 foot mark and see how far apart the lines are.

Hi Bob,

If the distance between the rifle and the branches is 25 yards as Chris has indicated, then how far away from the branches is the spot where the two holes were an inch apart? How far is the target from the branches? He doesn't say. The fact that at some unknown distance from the branches the bullets flight path is altered by one inch tells us nothing. However, if we knew the distance from the target at which the flight path was altered by one inch, and in what direction it was altered we could calculate the angle the bullet was deflected. With this angle you could project the miss distance at any range.

Instead of this, he makes a big deal out of saying the trajectory was only altered by an inch, just an inch. He is implying that this small amount of alteration is insignificant, but then goes on to state that the bullet would have ended up in the pavement. If the board with the two holes is close to the branches then obviously the angle subtended by that one inch at a distance of another 75 yards means a significant miss. The further the board with the two holes is from the branches then the smaller the miss distance. Assuming the board with the two holes was at 75 feet from the branch then 1 inch would indicate a very small angle of deflection. This was my point. He doesn't state the distances so we don't know.

Since they had the equipment, they could have measured the speed of the bullet after it impacted the branches. That would have been nice to know.

If we assume the target was a further 25 yards from the branches, then the results of this particular experiment are telling us that the impact with a branch would have deflected the shot too much to have turned a head shot into a back hit. The bullet penetrated 36" of pine. How much of its almost 2100 fps did it lose after penetrating 4 small branches? Could this bullet have caused a shallow back wound?

I'll have to watch the full video to see what their objective was.

Tom

[Chris Davidson]

In the second image posted by Chris D. the statement that "Nobody could have accurately fired that rifle from the way they had it "jacked up" in the window".

I think that the way it was "jacked up" is a result of their gross negligence in obtaining the wrong type of tripod. I'm assuming he is referring to the camera/tripod/scope setup the FBI used.

I have the same type and size of 60's style tripod, (that was my father's) with the same type retractable aluminum legs and looking at a photo of their setup I get the impression that the tripod is at it's minimum height. If the window ledge had been at a normal height there would have been no problem. I can imagine the total SNAFU situation when they showed up to do the photographic re-enactment. One word: incompetence.

Chris,

I believe they were actually recreating a pivot point (location at which the rifle body is attached to the tripod, indicated by intersecting red lines) with a height of 26 inches.

[Sandy Larsen]

Suppose you fired a 2000 fps bullet horizontal to the ground, it travels 85 feet, at which point it transits a block of wood just thick enough that it exits with a velocity of 380 fps. It continues to travel another 85 feet and finally hits a second block of wood.

Hi Sandy,

Glad to see someone else who is still trying to 'explain' the back wound. The thread you referenced just kinda ran out of steam...

My question, and I don't know the answer myself, is; How thick a piece of wood is required to knock 1700 fps (I don't know how much velocity has been lost while traveling the first 85 ft.) off the velocity of a Carcano slug? Did that oak(?) tree located between "the window" and JFK have thick branches where the trajectory would have passed?

Tom

Hi Tom,

I have no idea as to how thick a block of wood or limb would have to be in order to to reduce the speed of a 2000 fps bullet to 380 fps. Or if there were branches thick enough to do so in the line of fire. The answers to those questions would be useful in determining whether or not this scenario could explain the shallow back wound.

The purpose of my question to Robert is to see what it is about my simple analysis that he objects to. He apparently has a lot of experience with guns, an so I value his opinion.

Let me point out that my analysis involves only undeniably correct scientific principles. So his objection can only be with either my assumptions or my simplifications. (I simplified the problem so as to get a first order approximation. A more rigorous analysis is beyond what I'm willing t devote to solving this. But I do believe that my approximation would be reasonably close to reality.)

Robert has already pointed out that the bullet was likely traveling a velocity lower than the 380 fps I assumed for my analysis, and he presented a fairly convincing frame of reference supporting his case.