casette shifting, again

On Mon, 17 Dec 2018 16:30:07 -0800 (PST), wrote:

On Sunday, December 16, 2018 at 9:37:36 AM UTC-8, Frank Krygowski wrote:
On 12/15/2018 9:55 PM, Emanuel Berg wrote:
John B. Slocomb wrote:

In fact, this has nothing to do with any of
this. This is the bike culture which for
whatever insane reason is snobbish
beyond belief.

Hardly snobbish.

Not snobbish? Shave your legs? Remove your
helmet immediately after stepping of the bike?
If you don't, you are an embarrassment to
the sport?

Emaneul, you're shifting the discussion deep into your own imagination.
We're suggesting you gain enough fundamental knowledge to frame your
questions so we can understand them. Nobody has told you to shave your
legs or remove your helmet.

FWIW, I have never shaved my legs. I almost never wear a helmet. Get a grip!

--
- Frank Krygowski

What you have shown is that most of you on this group are both incompetent and an embarrassment to it altogether. This is the TECH group. It you can't answer a question get the hell off of it stupid.

A very well though out response from an individual who is, old, frail
and brain damaged. Or as described by William S., "Sans teeth, sans
eyes, sans taste, sans everything".

But more to the point, if you are not happy here why do you stay?

cheers,

John B.

On Tue, 18 Dec 2018 09:11:06 +0700, John B. Slocomb
wrote:

I'm not a ballistition (is that a word?)

Nope. That's someone who operates a ballista:
https://www.google.com/search?q=ballista&tbm=isch
Perhaps ballisticist?

but from what little I've
read none of the multitude of formulas actually provides accurate
results in all cases. See
https://en.wikipedia.org/wiki/External_ballistics
for probably more then you want to know :-)

I agree, if what I was looking for is a mathemagical way to calculate
the point of impact. That's quite difficult to do, considering the
accumulated tolerances of all the numerous factors involved (powder
load, temperature, humidity, altitude, wind, bullet weight, bullet
type, barrel friction, etc). Even an over-simplified tolerance
estimate of just the target width over the range is rather small. For
example, a 1ft frying pan at 300 yards is:
1ft / 900ft = 0.1% accuracy
Throw in all the other factors, and the % accuracy becomes much
smaller.

However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 18/12/18 1:58 pm, Jeff Liebermann wrote:


However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.



I have not read this entire thread, so I might be repeating what has
already been suggested.

*If* you know the ballistic coefficient of the projectile being used,
and most projectiles on the market have this data, then with the help of
an online ballistics calculator, and some careful target shooting under
favourable conditions, I think you should be able to estimate the muzzle
velocity reasonably accurately.

For a rifle like a .222 remington, for example, I would sight it in at
100 yards, then shoot a group with the cross hairs on the centre of the
target at 300 yards, & 500 yards if possible. Once the average (or
median perhaps) point of impact at each range is measured, use the on
line calculator to match the trajectory by iterating the muzzle velocity
until there is a match.

http://gundata.org/ballistic-calculator/

Mine are quite mild loads, and I estimate the muzzle velocity is
3100fps, for a 4" drop at 200 yards.

--
JS

On Mon, 17 Dec 2018 18:58:44 -0800, Jeff Liebermann
wrote:

On Tue, 18 Dec 2018 09:11:06 +0700, John B. Slocomb
wrote:

I'm not a ballistition (is that a word?)

Nope. That's someone who operates a ballista:
https://www.google.com/search?q=ballista&tbm=isch
Perhaps ballisticist?


Actually the Wikki has it that:
Balista or Ballista (died c. 261), also known in the sources with the
name of "Callistus",[1] was one of the Thirty Tyrants of the
controversial Historia Augusta, and supported the rebellion of the
Macriani against Emperor Gallienus.
https://en.wikipedia.org/wiki/Balista
:-)



but from what little I've
read none of the multitude of formulas actually provides accurate
results in all cases. See
https://en.wikipedia.org/wiki/External_ballistics
for probably more then you want to know :-)

I agree, if what I was looking for is a mathemagical way to calculate
the point of impact. That's quite difficult to do, considering the
accumulated tolerances of all the numerous factors involved (powder
load, temperature, humidity, altitude, wind, bullet weight, bullet
type, barrel friction, etc). Even an over-simplified tolerance
estimate of just the target width over the range is rather small. For
example, a 1ft frying pan at 300 yards is:
1ft / 900ft = 0.1% accuracy
Throw in all the other factors, and the % accuracy becomes much
smaller.

Accuracy is usually measured in "minute of angle" usually defined as
1" at 100 yards, 2" at 200, etc. With a rifle 1" or better at 100 yds
is real good.


However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.

Probably. If you take into consideration air resistance (density,
etc), gravity (is not a constant in real life), and probably other
factors.

cheers,

John B.

On 12/17/2018 9:11 PM, John B. Slocomb wrote:
On Mon, 17 Dec 2018 11:02:41 -0800, Jeff Liebermann
wrote:

On Mon, 17 Dec 2018 07:28:37 +0700, John B. Slocomb
wrote:

Acceleration of gravity = g = 32 ft/sec/sec
Let's say the trajectory height is 100 ft and the range is 1000 ft.
sqrt(height/0.5(g)) = time_of_flight
sqrt(100/0.5(32)) = (10/4) = 2.5 sec
At 1000ft, the muzzle velocity would be 1000/2.5 = 400ft/sec

Or something like that.

You are ignoring the effect of air resistance which means that the
speed of the projectile decreases with time during it's flight. And,
as the decrease in velocity results in an effective decrease in air
resistance the velocity decrease is not linier from muzzle to target.
For example, taken from a radar generated ballistics table a test
projectile fired at an initial velocity of 2,723 ft/s drops to 2,332
at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in
velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351
from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200.
:-)

Ok, I yield. Air resistance is significant and can't be ignored.

"Projectile Motion with Air Resistance"
http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node29.html
We thus conclude that if air resistance is significant
then it causes the horizontal range of the projectile to
scale linearly, rather than quadratically, with the launch
velocity.

Methinks I could use this to produce a tolerable balistic
approximation, which could be used to calculate the muzzle velocity
given the impact velocity at a known distance. However, my math
sucks, I'm still doing battle with two kidney stones, and need to do
some repairs after last nights rain. Thanks for the corrections.

I'm not a ballistition (is that a word?) but from what little I've
read none of the multitude of formulas actually provides accurate
results in all cases. See
https://en.wikipedia.org/wiki/External_ballistics
for probably more then you want to know :-)

One project I assigned in a sophomore dynamics class was using either a
program or a spreadsheet to compute a sphere's ballistic trajectory
stepwise. That is, starting with an initial speed and angle plus data on
mass, diameter, air properties etc., compute the drag force (assumed
constant for a chosen time interval), the X and Y accelerations, the
velocity at the end of the time interval, and repeat. We assumed a
constant drag coefficient, which was sort of OK for a sphere over a wide
range of speeds, but I think wouldn't work for a bullet.

Unfortunately we never had time to test that end-of-semester project,
although we did test a one dimensional version (dropping balls of
various sizes and densities) and got pretty good results.

--
- Frank Krygowski

On 12/17/2018 7:30 PM, wrote:
On Sunday, December 16, 2018 at 9:37:36 AM UTC-8, Frank Krygowski wrote:
On 12/15/2018 9:55 PM, Emanuel Berg wrote:
John B. Slocomb wrote:

In fact, this has nothing to do with any of
this. This is the bike culture which for
whatever insane reason is snobbish
beyond belief.

Hardly snobbish.

Not snobbish? Shave your legs? Remove your
helmet immediately after stepping of the bike?
If you don't, you are an embarrassment to
the sport?

Emaneul, you're shifting the discussion deep into your own imagination.
We're suggesting you gain enough fundamental knowledge to frame your
questions so we can understand them. Nobody has told you to shave your
legs or remove your helmet.

FWIW, I have never shaved my legs. I almost never wear a helmet. Get a grip!

--
- Frank Krygowski

What you have shown is that most of you on this group are both incompetent and an embarrassment to it altogether. This is the TECH group. It you can't answer a question get the hell off of it stupid.

Tom, you answered Emanuel's question, but your answer was wrong.
Specifically, the swept area is NOT why the forces are different between
disc brakes and rim brakes.

Not surprisingly, you don't know how very many times you spout nonsense
and people just don't bother to correct you. I mean, what's the use?

--
- Frank Krygowski

On Tue, 18 Dec 2018 14:16:59 +1100, James
wrote:

On 18/12/18 1:58 pm, Jeff Liebermann wrote:


However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.



I have not read this entire thread, so I might be repeating what has
already been suggested.

*If* you know the ballistic coefficient of the projectile being used,
and most projectiles on the market have this data, then with the help of
an online ballistics calculator, and some careful target shooting under
favourable conditions, I think you should be able to estimate the muzzle
velocity reasonably accurately.

Back when I was hand loading somebody published a M.V. chart for
several different calibers with different powders and bullets. I was
loading for the 22-250, which was a wildcat at the time, using necked
down 250-3000 cases and the most accurate load I could work out listed
on the chart at just a hair under 3,000 ft/sec. I had sold some to a
bloke that had them chronographed and (surprise) they were almost
exactly what the chart had said they would be.

For a rifle like a .222 remington, for example, I would sight it in at
100 yards, then shoot a group with the cross hairs on the centre of the
target at 300 yards, & 500 yards if possible. Once the average (or
median perhaps) point of impact at each range is measured, use the on
line calculator to match the trajectory by iterating the muzzle velocity
until there is a match.

http://gundata.org/ballistic-calculator/

Mine are quite mild loads, and I estimate the muzzle velocity is
3100fps, for a 4" drop at 200 yards.

Out of curiosity what size 5 shot groups could you get in perfect
conditions at 200 yards? I was building 22-250 varmint rifles back in
the '60's and I found that as soon as I got much over 3,000 ft/sec
(calculated) that accuracy dropped off. Probably due to bullets not
being as well made as they are today.

cheers,

John B.

On Mon, 17 Dec 2018 22:32:41 -0500, Frank Krygowski
wrote:

On 12/17/2018 9:11 PM, John B. Slocomb wrote:
On Mon, 17 Dec 2018 11:02:41 -0800, Jeff Liebermann
wrote:

On Mon, 17 Dec 2018 07:28:37 +0700, John B. Slocomb
wrote:

Acceleration of gravity = g = 32 ft/sec/sec
Let's say the trajectory height is 100 ft and the range is 1000 ft.
sqrt(height/0.5(g)) = time_of_flight
sqrt(100/0.5(32)) = (10/4) = 2.5 sec
At 1000ft, the muzzle velocity would be 1000/2.5 = 400ft/sec

Or something like that.

You are ignoring the effect of air resistance which means that the
speed of the projectile decreases with time during it's flight. And,
as the decrease in velocity results in an effective decrease in air
resistance the velocity decrease is not linier from muzzle to target.
For example, taken from a radar generated ballistics table a test
projectile fired at an initial velocity of 2,723 ft/s drops to 2,332
at 300 m, 1981 at 600, 1663 at 900, and 1384 at 1200. The decrease in
velocity and therefore the decrease in drag is 391 ft/s at 300 M, 351
from 300 to 600, 318 from 600 - 900 and 279 from 900 - 1200.
:-)

Ok, I yield. Air resistance is significant and can't be ignored.

"Projectile Motion with Air Resistance"
http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node29.html
We thus conclude that if air resistance is significant
then it causes the horizontal range of the projectile to
scale linearly, rather than quadratically, with the launch
velocity.

Methinks I could use this to produce a tolerable balistic
approximation, which could be used to calculate the muzzle velocity
given the impact velocity at a known distance. However, my math
sucks, I'm still doing battle with two kidney stones, and need to do
some repairs after last nights rain. Thanks for the corrections.

I'm not a ballistition (is that a word?) but from what little I've
read none of the multitude of formulas actually provides accurate
results in all cases. See
https://en.wikipedia.org/wiki/External_ballistics
for probably more then you want to know :-)

One project I assigned in a sophomore dynamics class was using either a
program or a spreadsheet to compute a sphere's ballistic trajectory
stepwise. That is, starting with an initial speed and angle plus data on
mass, diameter, air properties etc., compute the drag force (assumed
constant for a chosen time interval), the X and Y accelerations, the
velocity at the end of the time interval, and repeat. We assumed a
constant drag coefficient, which was sort of OK for a sphere over a wide
range of speeds, but I think wouldn't work for a bullet.

Unfortunately we never had time to test that end-of-semester project,
although we did test a one dimensional version (dropping balls of
various sizes and densities) and got pretty good results.

Somewhere on the Web there is a video of a group that dropped a
feather and an equal weight ball off a tower (actually a platform in a
tower). First under normal conditions a second trial after creating a
vacuum in the tower. You see it happen but emotionally you can't
believe it :-)

(I don't remember what the tower was built for but quite obviously not
solely for the test :-)

cheers,

John B.

On 18/12/18 4:01 pm, John B. Slocomb wrote:
On Tue, 18 Dec 2018 14:16:59 +1100, James
wrote:

On 18/12/18 1:58 pm, Jeff Liebermann wrote:


However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.



I have not read this entire thread, so I might be repeating what has
already been suggested.

*If* you know the ballistic coefficient of the projectile being used,
and most projectiles on the market have this data, then with the help of
an online ballistics calculator, and some careful target shooting under
favourable conditions, I think you should be able to estimate the muzzle
velocity reasonably accurately.

Back when I was hand loading somebody published a M.V. chart for
several different calibers with different powders and bullets. I was
loading for the 22-250, which was a wildcat at the time, using necked
down 250-3000 cases and the most accurate load I could work out listed
on the chart at just a hair under 3,000 ft/sec. I had sold some to a
bloke that had them chronographed and (surprise) they were almost
exactly what the chart had said they would be.


That is an extremely mild load for a 22-250, I would say. What weight
bullet? 70 grains or more?

For a rifle like a .222 remington, for example, I would sight it in at
100 yards, then shoot a group with the cross hairs on the centre of the
target at 300 yards, & 500 yards if possible. Once the average (or
median perhaps) point of impact at each range is measured, use the on
line calculator to match the trajectory by iterating the muzzle velocity
until there is a match.

http://gundata.org/ballistic-calculator/

Mine are quite mild loads, and I estimate the muzzle velocity is
3100fps, for a 4" drop at 200 yards.

Out of curiosity what size 5 shot groups could you get in perfect
conditions at 200 yards? I was building 22-250 varmint rifles back in
the '60's and I found that as soon as I got much over 3,000 ft/sec
(calculated) that accuracy dropped off. Probably due to bullets not
being as well made as they are today.


It has been a long time since I shot at paper targets, but I'm certain
my groups were smaller than 1" at 100 yards, so better than 2" at 200
yards I guess. Possibly down to 1/2" at 100 yards if I was lucky. I
used to shoot rabbits out to 200 yards quite frequently, and out to 100
yards with a .22 long rifle.

My .222 Remington has a stainless barrel that was re-bored from .17, and
the action is bedded in fibreglass and the barrel floated. A Remington
Model 700.

--
JS

On Tue, 18 Dec 2018 16:14:27 +1100, James
wrote:

On 18/12/18 4:01 pm, John B. Slocomb wrote:
On Tue, 18 Dec 2018 14:16:59 +1100, James
wrote:

On 18/12/18 1:58 pm, Jeff Liebermann wrote:


However, I'm not looking for the point of impact. I'm looking for the
muzzle velocity (given the terminal velocity at some known range). I
would guess(tm) that this could be calculated within to a reasonable
accuracy, such as +/-10%, without much difficulty.



I have not read this entire thread, so I might be repeating what has
already been suggested.

*If* you know the ballistic coefficient of the projectile being used,
and most projectiles on the market have this data, then with the help of
an online ballistics calculator, and some careful target shooting under
favourable conditions, I think you should be able to estimate the muzzle
velocity reasonably accurately.

Back when I was hand loading somebody published a M.V. chart for
several different calibers with different powders and bullets. I was
loading for the 22-250, which was a wildcat at the time, using necked
down 250-3000 cases and the most accurate load I could work out listed
on the chart at just a hair under 3,000 ft/sec. I had sold some to a
bloke that had them chronographed and (surprise) they were almost
exactly what the chart had said they would be.


That is an extremely mild load for a 22-250, I would say. What weight
bullet? 70 grains or more?

It probably is today as I read some very high velocity numbers for
reloaded today which I have read is due to better made bullets today.
Or it might be better to more progressive burning powders but I my
experience with what was available then is that very slightly less
then 3,000 gave the best accuracy. That was, of course, 50 years ago
and I'm sure that things are more refined then we had then. I don't
member the weight but they would have been speer bullets. standard
flat base and not the lightest nor the heaviest.

For a rifle like a .222 remington, for example, I would sight it in at
100 yards, then shoot a group with the cross hairs on the centre of the
target at 300 yards, & 500 yards if possible. Once the average (or
median perhaps) point of impact at each range is measured, use the on
line calculator to match the trajectory by iterating the muzzle velocity
until there is a match.

http://gundata.org/ballistic-calculator/

Mine are quite mild loads, and I estimate the muzzle velocity is
3100fps, for a 4" drop at 200 yards.

Out of curiosity what size 5 shot groups could you get in perfect
conditions at 200 yards? I was building 22-250 varmint rifles back in
the '60's and I found that as soon as I got much over 3,000 ft/sec
(calculated) that accuracy dropped off. Probably due to bullets not
being as well made as they are today.


It has been a long time since I shot at paper targets, but I'm certain
my groups were smaller than 1" at 100 yards, so better than 2" at 200
yards I guess. Possibly down to 1/2" at 100 yards if I was lucky. I
used to shoot rabbits out to 200 yards quite frequently, and out to 100
yards with a .22 long rifle.

A .22 is much more then the toy that a lot of people think it is :-) I
had a great uncle that shot white tailed deer with one and told me
that he rarely needed more then one shot.


My .222 Remington has a stainless barrel that was re-bored from .17, and
the action is bedded in fibreglass and the barrel floated. A Remington
Model 700.

The Remington 700 was probably one of the best actions ever made. But
re-bored? Wouldn't it have been cheaper to just rebarrel?

I had a .17 cal wildcat once. I built it on a small British made
Martini action - a "cadet rifle I believe was the description. Anyway,
it would shoot almost a one hole group at 100 yards for three shots
and then scatter holes all over the target. I always assumed it was a
matter of heat but never could get it to shoot a decent 5 shot group.
I finally sold it to a guy that was a varmint shooter and he was quite
happy with it as he might shoot 5 shots on a good day.

cheers,

John B.