Ballistic Calculator


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Online Charles Collins

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Re: Ballistic Calculator
« Reply #16 on: July 01, 2022, 09:31:18 PM »
Seems to me that when one is on the battlefield trying to avoid having
to learn German eventually, one can simply point-and-shoot at a Nazi torso
without needing a personal nerd tagging along with his degree in math.

___________________________________________________________

Shooting the 6.5 X 52 mm, 7.35 x 51mm Cartridges and the Carcano Rifles,
an article by Dave Emary, Senior Ballistician of Hornady Manufacturing


____________________________________________________________

The 6.5 X 52 mm cartridge has taken a great deal of criticism as being
underpowered and anemic. From a ballistic standpoint this is a little hard
to justify. The Swedish 6.5 X 55 mm cartridge is considered an outstanding
cartridge yet it is only able to produce 100 fps more velocity with a
156-grain bullet in the M96 rifle. The 6.5 X 55 requires a maximum average
pressure of 55,000 psi and approximately 6 more grains of powder to
produce this meager gain in performance. The . 30-30 Winchester, regarded
as an adequate deer rifle and known to have killed many moose and bear
produces 2,220 fps in a 24” barrel with a 170 grain bullet. The 6.5 X 52
mm fires a bullet with a higher ballistic coefficient, at a higher
velocity, shoots flatter and has far more penetration capability than the
.30-30. From the standpoint of a service rifle cartridge the 6.5 X 52 with
its relatively low operating pressure, coupled with its modest powder
charge would result in much less barrel throat erosion and wear. This
would equate to longer barrel life and decreased operating cost. In fact,
much of what was done in the Carcano rifle/ammunition system was aimed at
long barrel life, as will be shown later. From my point of view the 6.5 X
52 is a very efficient cartridge, offering adequate performance for what
it was intended.

The only fault that one might level against the 6.5 X 52 as a military
cartridge is that it had relatively humane terminal ballistics. The very
long, blunt nosed bullet coupled with the fast twist rate of the gun
resulted in a bullet that was very stable with a very high resistance to
tumbling. The cartridge was known to have inflicted many “through and
through” wounds, just leaving a small wound channel. The bullet
typically would not tumble inside its’ target unless it encountered
something hard such as bone. When it did tumble the wounding effect is
well known.

____________________________________________________________


The original 6.5 X 52 mm Carcano design used a gain twist barrel. The gain
twist results in a very slow initial twist in the barrel progressively
getting faster until the full twist rate is attained at the muzzle. The
slow initial twist results in substantially less torque being imparted to
the bullet during the highest loading phase of the interior ballistic
cycle. This results in significantly less barrel wear in the throat. This
coupled with the very deep rifling of the barrel would result in barrels
that would have a very long wear and accuracy life. This in fact is the
case. Many M91 model rifles show signs of considerable amounts of
ammunition being fired through them, because of the crazed/frosted
condition of the bore, yet still show very strong rifling and shoot well
with the proper size bullets. The 7.35 X 51 mm Carcano rifles used a
standard fixed twist barrel. The Carcano bolt is the model of a simple,
easy to field strip bolt. It is about as fool proof as you can get for a
common soldier. The Carcano trigger has taken a considerable amount of
criticism. The trigger is basically a Mauser type two-stage trigger. In
almost all cases if you find the trigger rough or creepy simply polishing
the sear and trigger mating faces result in a very acceptable trigger for
a military rifle. For the most part I have found Carcano triggers have
less creep, are more crisp and lighter than the majority of Mauser
triggers I have encountered.

The materials used in the Carcano are excellent. These rifles were made
from special steels perfected by the Czechs, for which the Italians paid
royalties. If you have ever tried doing any work on a Carcano receiver you
will find out just how hard and tough the steel is. The Carcano has also
received a reputation as being a “weak” design. Nothing could be
further from the truth. The Italians made a small run of Carcanos early in
WW II chambered for 8 X 57 JS. The Germans rechambered some Carcanos to 8
X 57 JS late in WW II. These rifles were also proofed for this cartridge.
The CIP minimum suggested proof pressure for the 8 x 57 JS cartridge is
73,500 psi. I hardly call this a weak action.

____________________________________________________________

The Italians apparently realized that a 300-meter battle zero was a bit
impractical and with the introduction of the M38 models went to a 200
meter battle zero. This zero results in a maximum height of trajectory of
5.5” – 6.5” at a range of approximately 100 yards, depending on
barrel length. With this sight setting, by simply holding on the middle of
the torso, it would have been hard to miss the target out to about 220
meters. The Carcano’s also used a unique sight picture. The proper sight
picture for regulated sights on a Carcano is with the front sight in the
very bottom of the rear sight groove. This is how the Italian army manuals
instructed that the sights be used. Potentially, this would allow for two
battle sight settings. The normal use as mentioned above would be a 200
meter zero. Using the Mauser sighting method, the front sight level with
the rear sight, would result in a zero of 330 – 350 meters. This is
about the maximum range practical for attempting to engage a target with
iron sights. I contend with the Carcano the Italians had a very
intelligent approach for a battle rifle. The fixed sights were basically
fool proof. The Italians must have realized with the M38 models that
nearly all small arms engagements occurred inside of 200 meters. The fixed
sights with a 200 meter zero would have been fool proof for a soldier
under stress, who was probably a poor judge of distance to begin with. The
soldier would have had to do nothing but point and shoot at the middle of
his enemy for ranges out to 220 – 230 meters. How much more simple and
effective could it have been made.

____________________________________________________________

6.5 x 52 mm

The Carcano rifles are capable of outstanding accuracy. With the exception
of a military issue type load in the short carbines they are very pleasant
to shoot from a recoil standpoint. Because of the above mentioned sight
picture for the Carcano, front sight in the bottom of the rear sight
notch, it is very important to have a consistent stock- cheek weld for
consistent accuracy. It is often very helpful to use a carbide lamp or a
sight black product to blacken the sights, which improves contrast and
sight picture.

____________________________________________________________

CONCLUSION:

The 6.5 X 52 is a very useful and capable cartridge. It served well as a
military cartridge for over 80 years. The 7.35 X 51 would have been an
even more effective military cartridge than the 6.5 X 52 had its timing
been different. It is interesting to note that the .308 Winchester / 7.62
X 51 mm NATO and the 7.35 X 51 mm are nearly the same dimensions. Both the
6.5 and 7.35 cartridges are fun to shoot and properly loaded capable of
very good accuracy. The Carcano rifle is a well made rifle that is by no
means weak or poorly manufactured. They are reliable and strong rifles
that are fun to shoot and offer a tremendous variety of types and markings
for the collector. I will admit that they are a rather utilitarian rifle
 as compared to some others. However, they are probably one of the most
efficient, cost effective, user friendly battle rifles produced in their
era. The rifle, ammunition combination properly loaded is capable of
accuracy that will rival the most accurate of the Mauser chamberings.

____________________________________________________________
Carcano Homepage: Italian Military Rifles and Carbines
http://personal.stevens.edu/~gliberat/carcano/


Agreed!  :)

Hitting the torso of a human enemy soldier is quite different than zeroing-in a telescopic sight for maximum accuracy at 100-yards. This is what Frazier and his team was trying to accomplish and had some difficulty with.

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Re: Ballistic Calculator
« Reply #16 on: July 01, 2022, 09:31:18 PM »


Online Charles Collins

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Re: Ballistic Calculator
« Reply #17 on: July 02, 2022, 01:50:41 PM »
A point I should make about the Carcano rifle.

Expert shooters, attempting really difficult shots, like between 1000 to 1500 yards, when they miss, they usually miss not because they didn’t line up the crosshairs on the target, but because they misestimated something.

They may misestimate the amount of crosswind. If they do, that could turn what would be an accurate shot at a human into a complete miss by several feet.

They may misestimate the range. The bullet start dropping pretty sharply after 1000 yards. A small error in an estimate of the range can cause a miss by several feet.

What would be useful, even for an expert, is a magical rifle that automatically provides the correct setting for the scope, to within two inches, every time. This would not guarantee a hit with each shot. But if the crosshairs were lined up on the center of the target when the trigger was pulled, the shot would hit, every time. And could do so with both stationary and moving targets, regardless of the speed or direction of the motion.

Oswald, at Dealey Plaza, with the Carcano, had a rifle that was as good as such a magical rifle. At least in the vertical. For all three shots, he would miss by less than two inches, high or low, if the iron sights were lined up with the center of the head.

Miss low by 0.8 inches for the first, miss low by 1.5 inches for the second, and miss high by 1.7 inches for the third.

The Carcano, of course, was not designed to do this, to provide a sighting that is accurate to within two inches at any range. Regardless of how the target was moving. No rifle can be designed to do that. Some weapon system could be designed to do that, I suppose, to use radar or some other method to automatically estimate the range of the target, and estimate the target’s velocity, and provide a scope that automatically makes the proper adjustment, but no rifle in the world can do this.

The Carcano did so by nothing more than luck. It just turns out that the Carcano, with the iron sights adjusted to 200 meters, just happens to provide a good adjustment for all three shots. Once the angular velocity of the target dropped low enough that Oswald was able to center the shots on the head, he made a successful shot.

I think that whether using the iron sights or the scope, it was a relatively easy shot. Frazier stated that the scope would have made it easier due to the 4X magnification. And below, he says no correction for lead was necessary on a target that size.


Mr. EISENBERG - Mr. Frazier, would you have tried to give a lead at all, if you had been in that position?
Mr. FRAZIER - At that range, at that distance, 175 to 265 feet, with this rifle and that telescopic sight, I would not have allowed any lead--I would not have made any correction for lead merely to hit a target of that size.

Offline Brian Roselle

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Re: Ballistic Calculator
« Reply #18 on: July 02, 2022, 09:37:42 PM »
Well, relative to my previous post my concern for the first shot was the small error of missing the target (impact inches) trajectory calculators would predict. But the first shot appears to have missed the limo and the rifle zeroing distance issue would not account for a limo miss. What I believe would account for it would require adding an additional term to Joe's model. That term could be called a Raw Aim Error (d aim) and is simply the error in aim off target (the total in y & z directions) determined at the time of trigger pull i.e. at the exact time the bullet exits from the rifle barrel. At the instant of shooting, errors due to gravity or limo/target movement downfield are not in effect yet so this is a separate error term.

If the first shot was a spontaneous effort in order to get off an extra shot close-in, there could have been some rush in aiming and trigger pull when not yet perfectly sighted on target and there definitely was a much higher angular velocity vs the third shot (perhaps as much as 9x higher angular velocity depending how early it was taken). This is what Joe refers to as the target motion settling down by the third shot. For the first shot, d aim would then be proposed to be the source of error that would make the Total Error enough to miss the limo (the bullet would need to miss its target by up to 3 feet to miss the limo). But looking at it another way, the aim error relative to how far the notched sight was momentarily aligned off target (slightly off target at its location on the rifle) at trigger pull, it would only momentarily have to have been about 1/2 inch off of a perfect alignment on target to have the shot miss the limo.

The error equation I am thinking about for the first shot is described below. I think Joe's approach covers all these error sources except for adding in the Raw Aim Error (d aim) which may have uniquely affected the first shot to where it could have dominated other values in the Total Error equation leading to missing the limo.

Nomenclature on terms:

x direction is the direction of the bullets travel. Generally considered essentially horizontal.

y direction is the up/down direction perpendicular to x (for most cases approximately parallel to both gravity and the direction bullet motion drop occurs)

z direction is the horizontal direction, left/right, perpendicular to x (for most cases involves a crosswind component and an error perpendicular to flight path and gravity)

Error terms based on [bullet deviation from path due to gravity (y) and crosswind (z)] forces:

d  yzero: the error in y direction due to error in zeroing the rifle for an expected fixed target distance. A gravity & flight time effect. This is from the effect of gravity acting on the bullet over flight time and is what a trajectory calculator apparently would typically do.

d  zzero: the error in the z direction due to error in zeroing the rifle for a crosswind for an expected fixed target distance.  A crosswind & flight time effect.
 
Error terms based on target deviation from path due to target movement during bullet travel.

d  target y: the error off target in y direction over time due to a target's x motion (change in distance which changes flight time while under the influence of gravity)

d  target z: the error off target in the z direction over time due to target's x motion (change in distance which changes flight time while seeing a crosswind)

The time of flight is dependent on the velocity and is simplified here by not digging into the effects of ballistic coefficient/velocity or head wind effects on slowdown. The trajectory calculators should automatically do that but these are probably not too significant here.

Total Error is sum of Raw Aim Error at trigger pull (beginning of bullet flight) and total errors accumulated after trigger pull (during bullet flight).
Total Error = d  aim + [d  yzero + d  zzero] + [d  target y + d  target z]

This is a simplified scenario and there may be other effects that I haven't included, but this is generally how I think I would address my initial concern.

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Re: Ballistic Calculator
« Reply #18 on: July 02, 2022, 09:37:42 PM »


Offline Walt Cakebread

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Re: Ballistic Calculator
« Reply #19 on: July 04, 2022, 04:12:50 AM »
Seems to me that when one is on the battlefield trying to avoid having
to learn German eventually, one can simply point-and-shoot at a Nazi torso
without needing a personal nerd tagging along with his degree in math.

___________________________________________________________

Shooting the 6.5 X 52 mm, 7.35 x 51mm Cartridges and the Carcano Rifles,
an article by Dave Emary, Senior Ballistician of Hornady Manufacturing


____________________________________________________________

The 6.5 X 52 mm cartridge has taken a great deal of criticism as being
underpowered and anemic. From a ballistic standpoint this is a little hard
to justify. The Swedish 6.5 X 55 mm cartridge is considered an outstanding
cartridge yet it is only able to produce 100 fps more velocity with a
156-grain bullet in the M96 rifle. The 6.5 X 55 requires a maximum average
pressure of 55,000 psi and approximately 6 more grains of powder to
produce this meager gain in performance. The . 30-30 Winchester, regarded
as an adequate deer rifle and known to have killed many moose and bear
produces 2,220 fps in a 24” barrel with a 170 grain bullet. The 6.5 X 52
mm fires a bullet with a higher ballistic coefficient, at a higher
velocity, shoots flatter and has far more penetration capability than the
.30-30. From the standpoint of a service rifle cartridge the 6.5 X 52 with
its relatively low operating pressure, coupled with its modest powder
charge would result in much less barrel throat erosion and wear. This
would equate to longer barrel life and decreased operating cost. In fact,
much of what was done in the Carcano rifle/ammunition system was aimed at
long barrel life, as will be shown later. From my point of view the 6.5 X
52 is a very efficient cartridge, offering adequate performance for what
it was intended.

The only fault that one might level against the 6.5 X 52 as a military
cartridge is that it had relatively humane terminal ballistics. The very
long, blunt nosed bullet coupled with the fast twist rate of the gun
resulted in a bullet that was very stable with a very high resistance to
tumbling. The cartridge was known to have inflicted many “through and
through” wounds, just leaving a small wound channel. The bullet
typically would not tumble inside its’ target unless it encountered
something hard such as bone. When it did tumble the wounding effect is
well known.

____________________________________________________________


The original 6.5 X 52 mm Carcano design used a gain twist barrel. The gain
twist results in a very slow initial twist in the barrel progressively
getting faster until the full twist rate is attained at the muzzle. The
slow initial twist results in substantially less torque being imparted to
the bullet during the highest loading phase of the interior ballistic
cycle. This results in significantly less barrel wear in the throat. This
coupled with the very deep rifling of the barrel would result in barrels
that would have a very long wear and accuracy life. This in fact is the
case. Many M91 model rifles show signs of considerable amounts of
ammunition being fired through them, because of the crazed/frosted
condition of the bore, yet still show very strong rifling and shoot well
with the proper size bullets. The 7.35 X 51 mm Carcano rifles used a
standard fixed twist barrel. The Carcano bolt is the model of a simple,
easy to field strip bolt. It is about as fool proof as you can get for a
common soldier. The Carcano trigger has taken a considerable amount of
criticism. The trigger is basically a Mauser type two-stage trigger. In
almost all cases if you find the trigger rough or creepy simply polishing
the sear and trigger mating faces result in a very acceptable trigger for
a military rifle. For the most part I have found Carcano triggers have
less creep, are more crisp and lighter than the majority of Mauser
triggers I have encountered.

The materials used in the Carcano are excellent. These rifles were made
from special steels perfected by the Czechs, for which the Italians paid
royalties. If you have ever tried doing any work on a Carcano receiver you
will find out just how hard and tough the steel is. The Carcano has also
received a reputation as being a “weak” design. Nothing could be
further from the truth. The Italians made a small run of Carcanos early in
WW II chambered for 8 X 57 JS. The Germans rechambered some Carcanos to 8
X 57 JS late in WW II. These rifles were also proofed for this cartridge.
The CIP minimum suggested proof pressure for the 8 x 57 JS cartridge is
73,500 psi. I hardly call this a weak action.

____________________________________________________________

The Italians apparently realized that a 300-meter battle zero was a bit
impractical and with the introduction of the M38 models went to a 200
meter battle zero. This zero results in a maximum height of trajectory of
5.5” – 6.5” at a range of approximately 100 yards, depending on
barrel length. With this sight setting, by simply holding on the middle of
the torso, it would have been hard to miss the target out to about 220
meters. The Carcano’s also used a unique sight picture. The proper sight
picture for regulated sights on a Carcano is with the front sight in the
very bottom of the rear sight groove. This is how the Italian army manuals
instructed that the sights be used. Potentially, this would allow for two
battle sight settings. The normal use as mentioned above would be a 200
meter zero. Using the Mauser sighting method, the front sight level with
the rear sight, would result in a zero of 330 – 350 meters. This is
about the maximum range practical for attempting to engage a target with
iron sights. I contend with the Carcano the Italians had a very
intelligent approach for a battle rifle. The fixed sights were basically
fool proof. The Italians must have realized with the M38 models that
nearly all small arms engagements occurred inside of 200 meters. The fixed
sights with a 200 meter zero would have been fool proof for a soldier
under stress, who was probably a poor judge of distance to begin with. The
soldier would have had to do nothing but point and shoot at the middle of
his enemy for ranges out to 220 – 230 meters. How much more simple and
effective could it have been made.

____________________________________________________________

6.5 x 52 mm

The Carcano rifles are capable of outstanding accuracy. With the exception
of a military issue type load in the short carbines they are very pleasant
to shoot from a recoil standpoint. Because of the above mentioned sight
picture for the Carcano, front sight in the bottom of the rear sight
notch, it is very important to have a consistent stock- cheek weld for
consistent accuracy. It is often very helpful to use a carbide lamp or a
sight black product to blacken the sights, which improves contrast and
sight picture.

____________________________________________________________

CONCLUSION:

The 6.5 X 52 is a very useful and capable cartridge. It served well as a
military cartridge for over 80 years. The 7.35 X 51 would have been an
even more effective military cartridge than the 6.5 X 52 had its timing
been different. It is interesting to note that the .308 Winchester / 7.62
X 51 mm NATO and the 7.35 X 51 mm are nearly the same dimensions. Both the
6.5 and 7.35 cartridges are fun to shoot and properly loaded capable of
very good accuracy. The Carcano rifle is a well made rifle that is by no
means weak or poorly manufactured. They are reliable and strong rifles
that are fun to shoot and offer a tremendous variety of types and markings
for the collector. I will admit that they are a rather utilitarian rifle
as compared to some others. However, they are probably one of the most
efficient, cost effective, user friendly battle rifles produced in their
era. The rifle, ammunition combination properly loaded is capable of
accuracy that will rival the most accurate of the Mauser chamberings.

____________________________________________________________
Carcano Homepage: Italian Military Rifles and Carbines
http://personal.stevens.edu/~gliberat/carcano/


Seems to me that when one is on the battlefield trying to avoid having
to learn German eventually, one can simply point-and-shoot at a Nazi torso
without needing a personal nerd tagging along with his degree in math.


Perhaps you'll be surprised to learn that Germany and Italy were "the Axis"  and fighting against The Allies...

Online Joe Elliott

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Re: Ballistic Calculator
« Reply #20 on: July 04, 2022, 06:42:11 AM »
If you are referring to the factory iron sights on the Carcano 91-38 rifles, it is my understanding that they are fixed (non-adjustable). And according to Joe’s ballistic calculator data, impact of the bullet would be 5.76” high at 100-yards. It would be ~0.1” low at 219-yards (200 meters). So, the shooter has to compensate accordingly when shooting at an distance other than the 200 meters that he factory iron sights are made for.

Most soldiers of the first have of the twentieth century were armed with rifles. Most casualties were caused, not by ordinary soldiers but by artillery (about 60%) or machineguns (about 30%). When an ordinary soldier, with a rifle, did inflect a casualty on the enemy, it was generally at short range, often with the entire body of the enemy visible. Most shooting may be at invisible or barely visible enemies hiding in trenches. But most shots that hit are at the rare times the enemy is totally exposed, either because they are charging, or the soldier in question is.

I remember reading some article on the Carcano, that an Italian soldier was instructed to always aim at the belt buckle of the enemy. That way, so long they were within 200 meters (a longer shot would likely be a miss anyway), they are guaranteed a torso wound, since the bullet would be off only between zero to six inches high. So, they were not instructed to adjust their aim depending on whether they were 20, 50, 100 or 150 yards away. Sometimes it's best to just keep it simple.

That is why the Italians went with non-adjustable sights, unlike most nations. They figured making a rifle that could hit at 300, 400, or 500 yards won't do any good for most soldiers, who are not accurate enough to get a hit at those ranges anyway. And gives one more way a soldier could mess up, by having his sights adjusted for long range just when he just needs a critical hit at short range (possibly just before the enemy is about to shoot him) and ends up missing a relatively easy shot at short range because the bullet flew too high.

A good weapon in war? Yes. A good weapon to assassinate someone, where you don't want the sights to be off by as much as six inches? No. Except at Dealey Plaza. Where all the shots were well under 200 meters and the rifle missing "high" actually give a pretty good lead (within two inches) of the target, which was always rising.
« Last Edit: July 04, 2022, 06:43:49 AM by Joe Elliott »

Online Charles Collins

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Re: Ballistic Calculator
« Reply #21 on: July 04, 2022, 01:00:04 PM »
Most soldiers of the first have of the twentieth century were armed with rifles. Most casualties were caused, not by ordinary soldiers but by artillery (about 60%) or machineguns (about 30%). When an ordinary soldier, with a rifle, did inflect a casualty on the enemy, it was generally at short range, often with the entire body of the enemy visible. Most shooting may be at invisible or barely visible enemies hiding in trenches. But most shots that hit are at the rare times the enemy is totally exposed, either because they are charging, or the soldier in question is.

I remember reading some article on the Carcano, that an Italian soldier was instructed to always aim at the belt buckle of the enemy. That way, so long they were within 200 meters (a longer shot would likely be a miss anyway), they are guaranteed a torso wound, since the bullet would be off only between zero to six inches high. So, they were not instructed to adjust their aim depending on whether they were 20, 50, 100 or 150 yards away. Sometimes it's best to just keep it simple.

That is why the Italians went with non-adjustable sights, unlike most nations. They figured making a rifle that could hit at 300, 400, or 500 yards won't do any good for most soldiers, who are not accurate enough to get a hit at those ranges anyway. And gives one more way a soldier could mess up, by having his sights adjusted for long range just when he just needs a critical hit at short range (possibly just before the enemy is about to shoot him) and ends up missing a relatively easy shot at short range because the bullet flew too high.

A good weapon in war? Yes. A good weapon to assassinate someone, where you don't want the sights to be off by as much as six inches? No. Except at Dealey Plaza. Where all the shots were well under 200 meters and the rifle missing "high" actually give a pretty good lead (within two inches) of the target, which was always rising.

 Thumb1:

Also, the line of sight from the fixed sights on top of the barrel is slightly different that the line of sight from the center of the barrel (bore). The bore line of sight is even more different from the line of sight from the scope which is mounted above the barrel. These line-of-sight differences also come into play when calculating off-target distances at targets closer than the zero-in distance.
« Last Edit: July 04, 2022, 01:14:58 PM by Charles Collins »

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Re: Ballistic Calculator
« Reply #21 on: July 04, 2022, 01:00:04 PM »


Offline Bill Chapman

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Re: Ballistic Calculator
« Reply #22 on: July 04, 2022, 01:34:11 PM »
Seems to me that when one is on the battlefield trying to avoid having
to learn German eventually, one can simply point-and-shoot at a Nazi torso
without needing a personal nerd tagging along with his degree in math.


Perhaps you'll be surprised to learn that Germany and Italy were "the Axis"  and fighting against The Allies...

No surprise here. In fact Italy declared war on Germany, switching sides in October, 1943.

Offline Gary Craig

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Re: Ballistic Calculator
« Reply #23 on: July 04, 2022, 04:27:09 PM »
Mr. Eisenberg.
Can you give us your position, Mr. Simmons?

Mr. SIMMONS. I am the Chief of the Infantry Weapons Evaluation Branch of the Ballistics Research Laboratory
of the Department of the Army.

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

Mr. Mccloy.
If you were having a dry run with this, you could certainly make yourself used to the drag in the trigger without
discharging the rifle, could you not?

Mr. Simmons.
Yes. But there are two stages to the trigger. Our riflemen were all used to a trigger with a constant pull.
When the slack was taken up, then they expected the round to fire. But actually when the slack is taken up, you
tend to have a hair trigger here, which requires a bit of getting used to.

Mr. Mccloy.
This does not have a hair trigger after the slack is taken up?

Mr. Simmons.
This tends to have the hair trigger as soon as you move it after the slack is taken up. You achieve or you feel
greater resistance to the movement of the trigger, and then ordinarily you would expect the weapon to have fired,
and in this case then as you move it to overcome that, it fires immediately. And our firers were moving the shoulder
into the weapon.

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

Mr. Eisenberg.
How did he do with the iron sight on the third target?

Mr. Simmons.
On the third target he missed the boards completely. And we have not checked this out. It appears that for the
firing posture which Mr. Miller--Specialist Miller uses, the iron sight is not zeroed for him, since his impacts
on the first and second targets were quite high, and against the third target we would assume that the projectile
went over the top of the target, which extended only a few inches over the top of the silhouette.

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

Mr. Eisenberg.
Do you think a marksman who is less than a highly skilled marksman under those conditions would be able to shoot
in the range of 1.2-mil aiming error?

Mr. Simmons.
Obviously considerable experience would have to be in one's background to do so. And with this weapon, I think
also considerable experience with this weapon, because of the amount of effort required to work the bolt.

Mr. Eisenberg.
Would do what? You mean would improve the accuracy?

Mr. Simmons.
Yes. In our experiments, the pressure to open the bolt was so great that we tended to move the rifle off the
target, whereas with greater proficiency this might not have occurred.

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

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Re: Ballistic Calculator
« Reply #23 on: July 04, 2022, 04:27:09 PM »


 

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