quote:

Originally posted by BigNate:


It seems clear to me that an overbore case vs straight walled will have more felt recoil due to the thrust over a longer time frame, where the straight case sees a much quicker drop in pressure so the velocity of the recoil drops quickly...

In the scenario of: .338win Vs 375 Taylor Vs .416 Taylor

Lets assume the .338win .375T and .416T are all loaded with a 300gn bullet...

Due to the extra time it takes to discharge an equal volume and pressure gas from the smaller orifice[muzzle],.. the .338win would have a longer thrust-gas discharge period/recoil period, than a .375 Taylor or .416 Taylor.

the .416T would have the shortest recoil period, followed by .375T and .338win ....simply because the larger .416 bore is able to offload gases more rapidly from the muzzle.[higher flow rate]
However,An equal volume of gas at the same pressure but higher flow rate,... means more thrust to push the rifle back...more thrust means a higher speed/momentum of rifle recoil.

If theres a higher flow rate of gas[of equal volume] leaving the muzzle[at same vel.& pressure],it must push the rifle back with more force/speed/momentum....albiet for a shorter duration than the smaller orifice[more restricted] 375T and .338win.

Because the .416 bore allows a higher flow rate of equal pressure gas to push the rifle back, the recoil would most likely feel more snappy[shorter duration-higher recoil velocity]

Powder burns and becomes gas. Gas exerts pressure equally in all directions as the bullet moves from case to muzzle.

Gas cannot have any influence on recoil, that one can measure reliably, until the bullet unplugs from the muzzle. The burn rate differences between usable powders, for a set of components, is seen in fractions of a milliseconds.

If anyone says he can feel the difference, it is quickly disproved with a blind test.

quote:

Originally posted by Gerard:
Powder burns and becomes gas. Gas exerts pressure equally in all directions as the bullet moves from case to muzzle.

Gas cannot have any influence on recoil, that one can measure reliably, until the bullet unplugs from the muzzle. The burn rate differences between usable powders, for a set of components, is seen in fractions of a milliseconds.

If anyone says he can feel the difference, it is quickly disproved with a blind test.

I think you may have misconstrued what was being said. No one feels the difference in the burn time itself. What they were saying is that they feel the difference caused by the greater mass of ejecta and the increased air resistance it meets at the muzzle.

A slower burn rate allows heavier charges of powder to be consumed. That creates more mass which must be ejected from the barrel.

Also as the slower powders cause higher muzzle pressures for several reasons, the gas velocity at the muzzle is higher, which acts to force the gas into the air outside the muzzle more quickly and has the same effect as shooting a bullet faster into the air...it increases the measurable air resistance to both bullets and gas. In turn, that increased air resistance to the gas increases the equal and opposite reaction force (the "rocket" effect) to some degree.

Ummmmm
The equal and opposite reaction of recoil energy is an equal an opposite energy reaction in the rifle to the work being done to GET the projectile to its muzzle velocity ........it equals the kinetic energy of the projectile at its muzzle velocity, but it occurs in those micro-seconds that elapse in travel down the barrel........not at the muzzle.
Ditto for the mass of gas in the barrel.
..........its an equal and opposite reaction to the work done to get the gas down the barrel to the muzzle.
At the muzzle & "uncorking" the higher velocity gas jet gives an additional recoil effect.

its a 2-part recoil reaction that occurs in microseconds that a shooter has enormous difficulty in sensing the different parts of.
ie
its sensed as a single recoil event.

Muzzle breaks only mitigate the gas jet recoil & can redirect the jet to oppose recoil force directions.

Go with as efficient a muzzle break as you like............you still have the recoil energy from the work of getting the projectile to accelerate to its MV.
.........and there is nothing you can do to mitigate that component of recoil in the rifle.

The whole recoil shebang is a very short time sequence of reaction events from energy expended
DOING work......... If you are thinking of it as energy gained by the projectile MV as recoil on ejection from the barrel muzzle you have your physics wrong.
Its not a big error tho........its just a microsecond or 2 in error of when it really happened regarding recoil from the projectile.
The gas energy & recoil is a lot more complex , but a part of it IS occurring in the barrel moving gas & unburnt powder down the barrel to completion of combustion.

A couple of microseconds between friends is piffling , but its there.
It shouldn't be a game breaker between friends tho...........its fun obsessing about it .

where & when recoil occurs is not going to help solve the myth the OP asked about........its essentially irrelevant to discussion of the myth.........the myth doesn't have a clue about where & why the recoil occurred........its just a myth.

never let facts interfere with a good story.
He He

BTW
a fast powder does more work in accelerating the projectile earlier in its travel down the barrel than a slower burning powder. a fast powder gives a "felt" sharper recoil from the projectile recoil. Shooter can sense that .......but still senses it as essentially a single recoil event.......blind test or not , the shooter's senses are the same......the shooter cannot feel & process the information any better & "feels" it as a single recoil event.

FWIW

AC,
I did not misconstrue anything. See my first post where I said: "The second is governed largely by the residual muzzle pressure and fast burning powder usually results in reduced muzzle pressure, compared to slower powder."

DenisB,

quote:

its an equal and opposite reaction to the work done to get the gas down the barrel to the muzzle.

This can only be true if the gas exerts pressure on the base of the bullet only and nowhere else. This does not happen. For the bullet to move down the bore, pressure has to be exerted on the base of the bullet as well as (simplistically) in the opposite direction. The pressure on the base of the bullet equals the pressure on the bolt face. How can it be otherwise?

Since this thread has focused more on recoil than velocity differences, I would add that there are several other very important variables that need to enter into any discussion about it. They are, IMHO, rifle weight and stock contour. For example, I have a 308 that kicks me harder than my 30/06s. Of course, it could be my hold but since this has been apparent over the years I don't think so. The 308 is lighter than the 30/06s.

Recoil:

Here is one for the naysayers of the concept of Sectional density.......

Recoil is a function of Sectional Density In fact if there was not such thing a SD there would be no recoil in our current gun systems

Recoil is a function of SD. Profound. Profound but reaching........

quote:

Originally posted by BigNate:
Please explain how it's possible to have two cartridges that are loaded to equal pressure, equal projectile weight, yet one is supposed to get higher velocity with less powder and less recoil.

Back to the original question... One doesn't need to know calculus to understand the principle of the area under the curve. That a longer time at a given pressure will produce higher velocity than a spike to the same pressure, and I think this is the best and simplest way to explain it.

However, I am having a harder time wrapping my brain around the notion that the same weight projectile fired at a higher velocity can produce less recoil. Yes, I've read everything in this string about the mass of the gas ejected, rocket nozzle effect, etc. It just isn't sinking in that the other variables could have a significant enough effect...

Again...recoil, as measure by most calculators has 4 COMPONENTS...Bullet weight, rifle weight, powder weight and velo...not just bullet weight and velocity alone.

As to the significant effect of each, of course some of the factors DO have a higher percentage of impact, but they ALL add up, each to a different extent depending on their individual weights and their precise changeability.

If two of the components are givens(set or unchanging) like bullet weight and rifle weight, THEN powder weight is the most significant component as it affects the final answer both by WEIGHT and the change in the velocity. Change the bullet weigh or rifle weight then THEY become the major factors.

The reduction of recoil by the use of muzzle brakes has been proven...you don't need to be a genius to see that.

The various parts/points of the gas jet can be adjusted to change the amount of recoil reduction, mostly by redirection but also by a change in powder amount.

There are several ways to mitigate recoil clear down to zero recoil by changing some or all of the 4 major components...

You have to think in terms of the WHOLE SYSTEM...not just the separated pieces and parts.

It's just a simple physics problem, nothing more.

You use LESS of the faster burning powders....less powder means LESS powder weight, which means LESS recoil and LESS powder gas...it just burns at a higher rate and moves the Pmax to a different point on the curve...and also has LESS gas exiting the barrel.

Pmax earlier in the Pressure/Time curve and also mean a difference in RECOIL VELOCITY which means a different subjective reaction to the recoil...getting hit with a quicker recoiling rifle usually means, subjectively speaking, a "HARDER" kicking rifle.

WHY is that so hard to understand...punch to data into a recoil calculate and see the answer...no thinking required, no headaches and no mathimatical/physics rhetorical BS.

This thread is turning into a total BLIZZARD OF "STUFF"...each trying to "baffle them with BS" or "blind them with brilliance"...and NOTHING is getting accomplished...as usual.

Luck

Gerard:

Never been more serious in my life.

Of course SD has a function in recoil, fer krissakes, Alf...SD is the mass(weight of the bullet)divided by its cross sectional area...the BULLET'S WEIGHT...WITHOUT BULLET WEIGHT WHAT'S THE POINT?? GRRRRRRR

You certainly DON'T shoot the mathematical concept of SD down the barrel of a rifle...you shoot the WHOLE bullet.

SD might have a large effect on bullet weigh as it is increased or decreased...but you don't weigh SD...you weigh the WHOLE bullet...and you don't input SD into a recoil calculator, you input the WHOLE bullet weight.

You can ALSO increase or decrease SD WITHOUT changing bullet weight...you just change the dia/length of the bullet, which in and of itself DOESN'T change the recoil...the recoil formula DOESN'T ask for bullet length or bullet dia...ONLY BULLET WEIGHT.

Don't be mucking about adding in any more extraneous "stuff"...that will only confuse an already TOTALLY confused and confusing issue... Hahahahahahah

Now this thing is going to head off in a totally new direction. Hahahahahahah

Luck

quote:

Originally posted by FOOBAR:
Again...recoil, as measure by most calculators has 4 COMPONENTS...Bullet weight, rifle weight, powder weight and velo...not just bullet weight and velocity alone.

I get that, and please don't get pissed if I am a bit thick headed. And I don't dispute anything you are saying... I understand how muzzle brakes work. Let me explain the part that is a little difficult for me to accept in a some more detail:

Assuming that bullet weight and rifle weight are constant, if one reduces the powder charge and uses a combination of case size and burn rate to produce a higher MV at the same peak pressure by manipulation of the area under the curve, I would think that the resultant higher MV would normally result in more recoil. In other words, it is hard for me to imagine that the reduction in powder weight would have a greater effect on recoil than the increase in velocity if all other variables were constant. (the powder weight being significantly less than the weight of the bullet)

If this is so I will press the "I believe" button and shut up. It just does not seem intuitively obvious that that would be the case.

energy = Mass X Velocity squared. The velocity of the escaping gases far out weighs the mass of the bullet. This is why muzzle brakes work.

"I believe" button pressed. Over and out.

quote:

Originally posted by Gerard:


DenisB,

quote:

its an equal and opposite reaction to the work done to get the gas down the barrel to the muzzle.

This can only be true if the gas exerts pressure on the base of the bullet only and nowhere else. This does not happen. For the bullet to move down the bore, pressure has to be exerted on the base of the bullet as well as (simplistically) in the opposite direction. The pressure on the base of the bullet equals the pressure on the bolt face. How can it be otherwise?

quote:

Originally posted by FOOBAR:

You can ALSO increase or decrease SD WITHOUT changing bullet weight...you just change the dia/length of the bullet, which in and of itself DOESN'T change the recoil...the recoil formula DOESN'T ask for bullet length or bullet dia...ONLY BULLET WEIGHT.

and Bolt thrust, is calculated by using the formula; Force = Pressure X Area

A cartridge with a larger dia. case head/larger internal cross sectional area, will produce more thrust/force on the bolt face than a cartridge with a smaller case head/smaller internal cross sectional area[at the same internal pressure]...

and likewise,...because of Force =Pressure x Area.... a larger bore 35Whelen-200gn will create a bullet with more momentum & velocity[at muzzle] than a .30/06-200gn,...

then should not the larger cross sectional area bore .35Whelen also push/recoil the rifle back with more speed and momentum than the smaller cross sectional area bore .30/06?

...or am I incorrect?

What the physics experts say?...

wait a second, I think I am incorrect,...the bore size/cross sectional area of bullet has increased from .30/06 to 35Whelen,...however the internal cross sectional area of the case head remain the same for .30/06 and 35Whelen. Hence the F=PxA factor has not changed in the case head of .30/06 and 35Whelen, so force in recoil motion of the 35Whelen and .30/06 should remain the same.

quote:

Originally posted by Gerard:

quote:

its an equal and opposite reaction to the work done to get the gas down the barrel to the muzzle.

This can only be true if the gas exerts pressure on the base of the bullet only and nowhere else. This does not happen. For the bullet to move down the bore, pressure has to be exerted on the base of the bullet as well as (simplistically) in the opposite direction. The pressure on the base of the bullet equals the pressure on the bolt face. How can it be otherwise?

Absolutely cannot be otherwise.
the effect of that pressure on the boltface is equal to the work done in accelerating the projectile down the barrel to its MV on exit from the barrel & occurs over the time it takes the projectile to traverse the barrel.
But its only one component of the recoil sequence .

Same load as a blank .......the recoil is very light as its only pushing the wad & powder/gas down the barrel........less work required.
( ignoring the combustion efficiency of the changed pressure situation the blank load creates).
The pressure of the powder combustion is exerted EVERYWHERE in every direction in the cartridge.......the directionality of the energy expended determines the equal & opposite reactions.......the barrel & the chamber shape determines directionality of the combustion energy converted into momentum & the kinetic energy of that momentum........equal and opposite kicks in and we get rifle recoil.
The big components are the projectile & the gas/powder moving down the barrel & the gas jet at the "uncorking".

The physics of the situation is absolute......you cannot create energy out of nothing.
all of the energy components incl projectile MV, gas/powder MV, gas jet, heat, noise,,,,, all have their energy basis in the powder combustion & the pressure it generates.
what occurs when and the efficiency of the recoil reaction is a complex dynamic, even the cartridge shape and what its made from affect the recoil energy that reaches the bolthead.

we can make it as complex and exact as we have the time to obsess about it , but some effects are small & not worth the effort to quantify them........the big parameters in the recoil sequence are the ones that dominate the free recoil & felt recoil, when & why they occur & the time sequence over which they occur & our ability to sense & discriminate them as a shooter.

Few of us have the physical ability to sense the recoil as other than a single event, as its occurring over such a short time interval.
what we physically sense tends to guide our simple concepts of what caused what we felt....thats human nature........physics & human nature aren't directly linked.
Physics is absolute
Human nature sometimes creates truths sometimes misguided myths.
Human nature creates myths by ignoring (or being in ignorance of) physical absolutes.

vis a vis
smaller cartridges with higher mv & lower recoil than bigger cartridges at the same pressure

quote:

Originally posted by Trax:

quote:

Originally posted by jeffeosso:

i find slower burning powders may kick MORE, but slower, than a faster burning powder....

Jeffe,
if the higher charge weight slower powders and the lower charge weight faster powders are loaded to the same pressure,velocity of exiting gases at the muzzle, would be the same.

dead wrong -- got an RSI pressure trace or other actual monitoring equipment? I have .. heck, even quick load will show you this, as faster burning powders then to be lower pressure at the end of the barrel... and build pressure quicker -- that's why they are called faster buring powders. MOST of the time, a slow powder, say h1000 will be BUILDING pressure at the end of the barrel, or at least still high in the curve, while h335 will be burnt

quote:

Originally posted by Trax:


Hence thrust the rifle back at the same initial rate,yet the gas flow duration period from the muzzle, would be less for the faster powder lower gas volume charge,...correct?

first part was wrong, the conclusions afterward are false

quote:

Originally posted by Trax:

With gas velocity being the same for both loads[at the muzzle] immediately after bullet departure,

they aren't the same in volume velocity, or pressure

quote:

Originally posted by Trax:
I dont see one resulting in a slower recoiling rifle than the other , just a difference duration period for gas flow.

however, i bought the testing gear to prove what i felt in terms of recoil.

quote:

Originally posted by Trax:
Hence the faster powder load with its same gas vel. but lower gas volume charge, would thrust the rifle back for a shorter period of time, resulting in lower recoil momentum.

quite a few assumptions here

quote:

Originally posted by Trax:
One way of putting it would be that;
- the faster powder charge results in a shorter pulse/burst?/duration of gas discharge-rifle push back,... the slower burning-higher charge weight powder would offer a longer pulse/burst period[due to higher gas volume], but not necessarily a slower gas vel. or slower rifle recoil velocity.

quote:

Originally posted by ALF:
Recoil:

Here is one for the naysayers of the concept of Sectional density.......

Recoil is a function of Sectional Density In fact if there was not such thing a SD there would be no recoil in our current gun systems

Well SD is a function of bullet weight and cross-sectional area I think.

So the bullet's weight and cross sectional area encompass things like bore size (absolutely), engraving area(approximately), powder charge (Indirectly, according to some constant derived from the the cartridge design) and speed (Indirectly, depending on powder charge).

It would seem that these are all of the factors relating to recoil, unless I've got this completely wrong?

Foobar:
I'm not headed anywhere man, just staying on track here

This is classic Mr Newton in practice with a few few red herrings thrown in to confuse!