Got into a discussion this AM after a couple rounds of skeet when one of my compadres saw the sorry condition of some of my 20 ga AA's. I understand there is no direct relation of pressure to recoil but it seems there must be some relation of pressure (lower somewhat when the mouth of a hull is cracked and degraded) to velocity. Maybe depending on the burn rate of the powder, the pressure where it counts (near the muzzle, I suppose) and ultimately the volocity of the shot, could be affected by the condition of the hulls.

I can't remember where I read it, but there were pressure tests done on hulls as they aged. It seems the roughness of the hull interior increases pressure to a degree, offsetting some of the degradation of the hull mouth unable to crimp as well.

Simple statement, without pressure there would be neither velocity nor recoil.
However the thing often misunderstood is Neither is directly related to "MAX" chamber pressure.
Bottom line is recoil is determined by total ejecta weigh & the velocity it is given, but the velocity of that weight is determined by the Total pressure curve pushing it. Thus both velocity & recoil are controlled by pressure, just not the Max pressure but total pressure.

Pressure will be lower if the cartridge does not have a good crimp. I do not remember how much this effects pressure exactly.

I think 'total impulse' might be a better term Miller.

That is what is represented by the area under the pressure curve. "The work done".

If the pressure never reaches the intended initial value, the area will likely total lower.

Crimp condition and crimp depth both affect initial pressure rise. The shell closure resists the initial payload movement thus allowing the pressure to build up to the design optimum for the powder charge.

A new shell is best, and it's downhill after each firing.

Is it a problem? Not a huge one since shotgun powders are on the fast end of the range of smokeless powders, especially those used for target loads.

Where crimp problems might get serious is when using slower powders in cold weather. It's best to use only new or once-fired hulls for field loads.

Jones;
You are correct, total impulse is a more descriptive term. Was mainly just trying to make the point that Max Pressure is not the final outcome on this Total Impulse. You can with many loads have more total impulse while maintaining a lower Max pressure.

While I do not actually have the necessities of checking it I do believe that in most cases "IF" using the same identical charge if the max is lowered then the total will be lowered as well. Thus when a weak crimp lowers the initial pressure rise, lowering the max it is also going to result in a lower total impulse thus lowering the velocity as well.
I am thus in total agreement of your assessment of new versus older shells & particularly where slow powders in cold weather come into play..

I think this is the Tom Armbrust article referring to case life and velocity. Case life has little effect on velocity

http://www.armbrust.acf2.org/caselife.htm

Most of the answer is in the responses above. But it always boils down to how you want to define "recoil". In its simplest form, total energy ( joules, lbs/foot, etc) of the recoil gives us something we can work with. But we need a lot more before we can tell how it will feel.

Three 7 lb long guns with the same stock-barrel geometry and same butt configuration. One black powder rifle, one Shotgun, and one magnum rifle.

Assume these all fire loads producing recoil of the same total energy. One will always have recoil with higher peak force than the other two. In this example, it's the magnum rifle. It will have a high peak force push the firearm, but it will be for less time than the others. This can clearly be "felt". If you don't believe that, you don't believe in recoil pads and hydracoil systems.

Recoil is force/time, to me. Your definition may be different.

Interesting article by Armbrust.

It reads like an ad for modern components.

Modern components are indeed very good, but...

Only one powder was tested.

Only light target loads were tested.

The concluding comments about weak crimps and field loads with slower powders while traditional common wisdom and undoubtedly correct is not supported at all by his data in the article! He didn't test any!

This whole waste of ink is ONE data point about American Select which is a good powder but hardly universally used. It's not the most cost effective powder, thus has not captured a dominant market share.

I would not extrapolate this to other powders, especially anything with slower 'relative quickness' like Green Dot, Universal, etc.

Chuck;
What you say is of course correct. "However" comparing a magnum rifle with a shotgun is somewhat akin to comparing apples with oranges.
I do feel this bit of "Felt Recoil" has been much overplayed. For instance for many many years Hercules RedDot was the primary powder for loading the 3-1 1/8 skeet/trap loads @ 1200 Fps. Along in the early 90's I believe it was they introduced a new powder which was very slightly slower than RedDot but faster than GreenDot. Much Ado was made over how this "Slower" powder would reduce the "Felt" recoil. If both powders were loaded to give identical velocities there was less than a grains weight difference in the powder charge. I truly doubt that 1 person in a Thousand could actually "Feel" a difference in the recoil which of course would have had identical recoil energy. There does have to be some amount of difference for us mere humans to detect. Pressure curves for all [powders suitable for loading shot shells are quite close together. One could quite possibly "Feel" a difference between say RedDot & BlueDot, but these two powders are not suitable for loading the same shot weights to the same balilstics.

I think a better description of this comparison would be to consider just using the term rifle, instead of magnum rifle. The felt recoil difference of say a 30-06 compared to a 300 Win mag is very significant to most folks. The higher end of 12 ga slug, or magnum hunting load, muzzle energy is probably similar to the 30-06.

Even with full knowledge that the configuration of the firearms are different, now my subjective impression is that the slug gun is punishing and the 30-06 isn't too bad at all. I'd agree though that the shorter duration of the rifle bullet in the barrel feels like a sharper pop during recoil to me.

In response to the OP original Q

Don't worry about the condition of the cases as long as tape will cover the splits. You will never feel the difference. The gun will never know the difference. The target will never know the difference.
Some people take great pride in loading some particular case 20 times or more. Personally I could GAF. Reloadable 12ga cases are free for the picking up. When I was loading I used them once and tossed them with no regrets. No reason other than why bother. Now that reloading has become an economy of questionable worth I no longer bother at all and just blast away with the cheapest carts that come to hand - mostly Feds but some Wins as well. NBD in any event.

Seems like lotsa folks get twisted panties over inconsequential minutia. Worry about something important

It's a discussion forum, Wonk. We don't GAF that you don't GAF.

Your point that reloading is of 'questionable worth' is true to an extent. If standard promo target loads suit your shooting, there is little need to reload, at least for 12 gauge.

The extra performance of good high Sb shot in premium target loads comes at a price. I can load a premium target load for the cost of factory promo loads. Another apple/orange deal.

Anybody who shoots 410 more than a flat a year reloads or is wealthy. In spite of Armbrust, the STS 410 hulls are worthless. In 12 and 20, STS is king of the hill but in 28/410 AA is far superior. In spite of the recently observed 28 gauge AA brass splits It's still the best component hull.

It is worth noting that everyone uses 410 hulls until they will no longer hold the shot charge and it all ends up in their pocket, so maybe this crimp strength business is in fact a tad overblown.

Some might say they don't want to analyze this beyond a certain level. It's human nature to stop any analysis at the point you believe provides you with the information you are seeking.

The value of pursuing the analysis until the key variables are quantified is that you can then insert a new variable, such as gun weight, and calculate a quantifiable set of recoil attributes.

I like these kinds of discussions as long as we have folks who will join in peacefully. Just for the fun of it a I ran a few figures. Take 1 1/8os shot, 35 grains of wad & 20 grains of powder. Total weight o be ejected out the barrel is then 1¼ oz or .078 lb. Fire this load from a 28" barrel on a 6½ lb gun. Now yes I know that the ejecta would not move quite the full 28" but I used that figure anyway. While this load traveled that 28" the gun would have traveled in the opposite direction 5/16" & attained a recoil velocity of 14.4 FPS giving it a recoil energy of 20.93 ft/lbs.
Over the years I have formed the Firm conclusion that Recoil Velocity is of far greater importance than Recoil Energy. This is why the old British formula of a 96:1 ratio of gun to shot weight works. 1 oz of shot from a 6 lb gun & 2 oz of shot from a 12 lb gun if given the same muzzle velocity will recoil at essentially the same recoil velocity, though the heavier gun would have twice the recoil energy.
I have in the past shot both. The big Ten while obviously heavier in recoil was not at all uncomfortable. "IF" on the other hand one were to raise the velocity of that 1 oz in the 6 lb gun to double the energy or equal that of the big Ten, it would be Absolutely, Tetotally, Unbearable.

The 'Old Cowboy' rather told me off when I opined that without the muzzle brake my 300 WBY was unshootable.

Tolerance varies.

Or at least people claim so.

Looking back at the original recoil scenario. All three examples of recoil were created by the exact same 'total energy', yet they are perceived differently.

I'm not sure what 'peak force' is. Is it expressed as peak chamber PSI, or is it the mass of the payload x acceleration?

If all the variables have been equalized, including the total energy of the payload leaving the gun, it seems that recoil perception, is purely time related. Is it, the longer time it takes for the payload to separate from a gun with equal opposing force, the less recoil that's perceived? Then a question might be, if all else is equal, what amount of change in time can be perceived as different.

Craig;
The total recoil energy is determined solely by weight & velocity.
Where the "Felt Recoil" comes into play is based on rate of acceleration, The quicker the acceleration, thus shorter barrel time to achieve that velocity the "Sharper" the recoil. While I in no way question this concept I do have some reservations concerning all the "Hype" sometimes published on Felt Recoil.
The big deal here is as you mentioned "What amount of change in time can be perceived as different".
While I do not have any concise answers on this I do have grave doubts that within the parameters of a powder of suitable burn rate for a given shotgun load that there truly is a "Feelable" difference in actual acceleration rates.
For instance to load a 1 oz shot charge to 1200 FPS powders in the range of Red Dot to Green dot are going to be suitable, regardless of brand name on the can. Start going to much slower powders then you are courting squibs & failures.This is particularly applicable if you are going to use the loads when temperatures may fall down in the below freezing range as in hunting loads. For strictly Hot weather use one does have a bit more lee-way but I still do not like these Extremely "Low Pressure" loads. I realize many here will disagree with this but this is using those powders in a way for which they were not designed nor intended.

Not sure if this is relevant to the actual topic discussed but I purchased several cases of B & P shotshells. There is a noticeable difference in felt recoil reduction using these shells. Prior to this I thought the "Gordon System" they advertise was just hype. Wrong. I would guess this is a "crush system".

Many here are aware of Neil Winston's work, which includes the only to my knowledge single blind sorta controlled study regarding the ability to perceive fast vs. slow powder recoil curve www.claytargettesting.com



As a victim of a State of Missouri public education, here's the non-deep thinking version.

1.Recoil is easily calculated: http://www.handloads.com/calc/recoil.asp

as is Recoil Velocity http://www.loadammo.com/Topics/August01.htm

2. Perceived or 'felt' recoil is almost impossible to define. Good science is reproducible and measurable and there is no 'pain-o-meter' because pain is entirely subjective. One can measure the difference in perceived pain OF an individual but not BETWEEN individuals. One person may rate the recoil of the same shell and gun as a 7 and the next a 4.
And perceived pain is highly variable and dependent on multiple external and internal physiologic factors ie. pain seems worse at night when there are fewer external stimuli. One's assessment of recoil when shooting a record Kudu vs.sighting in the .375 is entirely different. 'Felt' recoil may differ based on too much coffee that morning or too much alcohol the night before, fatigue, sleep deprivation, stress, or anxiety. And stock design/gun fit/muzzle jump contribute significantly.

But a smart guy is working on understanding, or at least quantifying, 'felt recoil'.
https://www.researchgate.net/publication/223811001_Measuring_felt_recoil_of_sporting_arms

And breaking news from 1897

Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the “Field” Newspaper, Relative to Firearms and Explosives, Volumes 1-2, 1897
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA197
“Some Notes on Recoil”

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA254
It is a fundamental principle that action and re-action are equal and opposite; therefore, at the moment when the shot leaves the muzzle of the gun, the momentum (or weight x velocity) of the shot will be equal to the momentum of the gun. This is strictly true from the tune the shot first commences to move until it finally leaves the muzzle, but only up to that instant.
On no subject in connection with gunnery are there more erroneous ideas—superstitions one might almost call them—than on recoil. Many men will tell you that certain guns, with precisely the same ammunition, will give much more recoil than other guns of exactly the same weight. It will generally be found that these men are either novices in the art of shooting, or else they do not hold their guns properly up to the shoulder. Once and for all, it may be laid down that the recoil of guns, rifles, and arms of every description, from the smallest pistol to the heaviest piece of ordnance, proceeds from the same causes and depends upon the same elements.

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA266
“judging of the weight and nature of recoil by the feeling alone one is apt to be misled; for according to the state of bodily health at the time, so will be the sensation produced by a normal recoil…”

Drew, That's a great paper on the subject.

et al, note that his charts all include force and time. One without the other is incomplete.

I also think it's a great paper, that I wasn't aware of. The two points in it that I can't help but notice are, the data showing lower peak force over a longer duration was plotted by changing to ammunition that generated intentionally different muzzle energy, the three different Win AA's. The other point is that, in the conclusion, the device is intended to quantify felt differences in the gun, where the ammo is a constant.

My original point was nothing more than it may be atypical to be able to match similar total energy of a 12 ga shell and a magnum rifle cartridge, which I attempted to quantify as muzzle energy.

I'd say our GAF quotients are good all around.

Nice to see that Drew has brought up Mr. Winston, the teller of unfortunate truths. Any and/or all of you are certainly welcome to believe whatever you care to, but Mr. Winston does repeatable, verifiable scientific studies of many of the wonderful Hogwarts Physics contentions that inhabit the shooters' internet.

His so-far unrealized hope is that persons can be self-enlightened if presented with facts. I have wished him the best of luck on several occasions and he has been appreciative of my continuing support. But he hasn't given up even under circumstances that boggle the mind. Even as will certainly occur here. Hopefully he will not subject himself to this place as well.

In many shotshell loads utilizing the "New Fangled" Dense Smokeless Powders the powder charge is no more than 5% of the total weight being launched from the muzzle. With ordinary porting nowhere near all of these powder gases are going to be diverted. As far as recoil reduction in a shotgun goes porting is insignificant & essentially useless. I Ain't a-drilling No Holes in any of my barrels nor letting anyone else do it with my knowledge.

There was a bunch of good stuff, then you kinda lost me at the end. What's the point of luck, when he could have a day.

To the OP's question, there was an article or series of articles published in Handloader Magazine at a much earlier time where the same hulls, 12ga. I believe, were basically loaded until the mouths were shot off or so sorry they would no longer hold shot w/o some added closure devise and both pressure & velocity was measured at each loading. If I recall correctly, there was some degradation of attained velocity, but it wasn't particularly significant even when it was the hulls' last usable loading and pressure was highest on the first reloading as could be reasonably expected.

Pressure & velocity are two dif. animals not related to one another in any mathematical sense as has been noted here and other places multiple times and will only say to not lose sight of that fact.

In my own experience, the yellow 20 ga. hulls get uglier looking [dirty] quicker than the other gauges. Purely a color thing, IMHO, but the hulls are easily enough acquired, so I toss them when they get ugly, tho they would continue to break targets for more reloading's. Mostly the only dif. between once loaded and multiple loadings for skeet ranges is your fingers get dirty along w/the hulls if you don't wear shooting gloves. I don't notice that it affects the numbers of targets broken when the gun is pointed correctly. Dirty hulls breaking as many targets as new ones. Head games are a dif. horse; if you THINK it makes a dif., it probably will and it need not be based on fact.

Phraseology & word choice aside, whot Wonk is saying is the essence of it; don't get too caught up or caught up at all w/meaningless and often wrong minutia as tempting as it may be or as Joe Friday was famous for saying, "Just the facts, Maim."

And please don't read into my remark(s)anything snarky, no intention in that regard exists whatsoever nor trying to refute correct math or that the 96:1 rule is not a fine one for rational limits. It is, but it is also too stout for me were I to shoot many rounds in a day's time. And there is no connection to that and the OP's question either, unless I misread it.

Even though it may be thought of as minutia, I figure truly, what's the big deal. It's only conversation for the fun of it.

If something, referred to as pressure, didn't move a given mass of shot from still and accelerated it to a velocity, what force caused it?

TW,
I'm surprised you drank that water.

Of course pressure and velocity are linked mathematically. Pressure, area which the pressure is applied, and weight are the key physical attributes

Chuck is 100% correct here & both velocity & recoil are dependant on that pressure being applied.
The thing is However neither Velocity nor Recoil can be determined by a comparison of "Peak/Max" chamber pressure.
By using different powders you could load an ounce of shot to 1200 fps @ 10K PSI while you could also load 1¼ oz to 1300 FPS with only 8K PSI.
Thus there is no direct relation between "Max" pressure & either velocity or recoil, but there definitely is a mathematical relation between pressure & either velocity or recoil.
About all most of us have the means of measuring is the MV. Using that in conjuction with total weight ejected we can then calculate the recoil.

All of the physical components: peak pressure, average pressure, base area (bore) of the ejecta, weight of the ejecta, and time, are all inseparable pieces to the acceleration of the ejecta... and which leads to the opposite reaction, acceleration of the firearm.

At peak pressure, the ejecta will be accelerating at its highest rate (g-force), unless it's constrained from movement. The peak acceleration of the ejecta will coincide with the peak acceleration of the firearm in the opposite direction (not the peak velocity of the firearm). Those recoil charts in Drew's reference tell a lot.

You're both correct. Probably shouldn't have gotten my feet wet or even waded in. Left out the direct correlation between velocity to Max pressure part didn't I. There isn't one that will stand alone.

Only point that I was trying to make & did a poor job of is that velocities from the low noise/low-recoil levels in the 900+fps range can and do break clay targets as well as suitable sized pellets traveling at 1200fps & more and that Max pressures running from as little as 5K to industry Max levels can and have been measured in some published recipes and they all will work at skeet ranges.

Wonk's saying the cartridge, shooter & target would not know the dif. is an accurate assessment when applied to the OP's Q regarding worn hulls & ugly mouths.

Will also acknowledge that most powder companies avoid publishing low Max pressure loads and I have been told by more than one ballistician employed in the industry it is because reliability is frequently compromised at low temps w/many loads below 7K even though they may be fine in our triple digit summer temps here. Little point in publishing a recipe that might lead to their product being spoken ill of.

OTOH, using PB in 12ga. rounds, if you are fortunate enough to have any, can produce adequate velocity w/quite low Max pressures even in cold temps, not that it was asked.

Best I stop digging, eh? This hole is deep enough. Y'all have a great day. I'm going to the club and shoot [or shoot at may be the better descriptor] some clays.. w/ugly reloads;-)

As Chuck mentions, peak acceleration is correlated with peak pressure. The peak occurs in the chamber, and overcomes the payload inertia 'right smartly'.

It's not just accelerating, it's accelerating to beat hell.

Butler's data from Winchester shows a 3 dram one ounce load attains 1,000 FPS after 7" of payload movement. 7" !

It's been common wisdom for some time that all that force can't help but mash the poor pellets out of round traversing the chamber cone and being shoved into a narrower tube, so over boring has become almost universal to 'improve patterns'.

Then Winston comes along and says it makes no difference. With test data and pronouncements from the oracle of Jones, he claims it's all smoke and mirrors and does nothing at all.

Yet, in a another of his articles in Drew's reference he extols the virtues of 'extra hard' shot as being an essential contributor to throwing winning trap patterns.

Anyone care to reconcile those two conclusions?

This seems to point to acceleration deformation as being the primary, indeed the only, cause of out of round pellets.

If so, would not a more gentle acceleration such as provided by a slower powder result in tighter patterns?

Were this true, Unique should outshoot Red Dot every time.

The pronouncements and denials of Mr. Winston's contentions is no surprise. Faith conquers all. Belief systems are incontestable. Simple facts are easily ignored when such overwhelming evidence of experience is available. Not to mention the superiority of Hogwarts Physics. And we all know that anyone else's data is prima facie inferior to our own regardless of derivation.

Shot deformation in the choke is generally considered to be the origin of the squashed hence the usual superiority of harder shot pattern-wise. I think I recall some patterning studies of plastic wad vs fiber that lent credence to that contention as well.

Rather an interesting post from one whom we know from the 'one pellet break' discussions does not worship at the altar of Jones.

Do tell how a choke functions while imparting the claimed deformation. Note that choke works with soft or hard shot, and that even patterns with no choke are improved by hard shot.

Ever pick up a fired wad? We are launching a lot of little dodecahedrons. Is it likely they originate where the pressure is 10K PSI and the acceleration is at max or in the choke where the pressure is 500 PSI (tops) and the load is accelerating at 20 fps?

That's a joke, right?

Keep trolling tho, you might find someone who wants to play

I'll play, in the interest of science

Why does Hevi-Shot fly true/pattern better than round shot? The shuttlecock effect?



and what about Winchester Hex shot?
https://www.americanhunter.org/articles/2011/9/9/winchester-blind-side/

and Federal Black Cloud FliteStopper spaceships
https://www.federalpremium.com/products/brands/blackcloud.aspx

The peak rate of acceleration is necessarily higher in the rifle example because we know the ejecta separates from the gun at a significantly higher velocity. But, the peak force at the moment of highest acceleration is no more than it takes for the smaller bore and lighter ejecta mass to overcome its resistance.

In identical guns in every way, including the total force of the ejecta clearing the muzzle, the rifle will have some higher peak force. But, only to the extent that the area under the graph for total force can be identical to a slower, heavier shotgun load over a shorter period of time.

Doc Drew's article by Hall took pains to assure constants in the devise he used to record the measurements, but he also wanted to document that the ammo he used was a constant. His conclusion was that he could test a different gun and predict differences in how recoil would be perceived.

I never realized that type of recoil study was available, but all else being equal, what did it reveal about differences in felt recoil between heavier/slower and lighter/faster equal energy loads? If peaks and totals happen over very short periods of time, how discriminating could the human be. It seems like Hall measured a vertical rise component, that may be interesting in the longer duration of a slower shotgun load.

Maybe, more pop in the cheek would be perceived as more felt recoil than accelerating the gun at a higher rate directed more inline with the shoulder. But, the conclusion was that the magnum rifle would necessarily generate more felt recoil due to a higher peak contained within the total duration of firing the ejecta. Only in light hearted fun Chuck, and I remain open to understanding what I'm missing in those recoil charts.

Drew, maybe Winston could shed some light on that.

Me too.

Another little tidbit here, related to some of the posts, but not the original.
Pure lead has a Brinell Hardness of about 5. Lead will begin to deform at a pressure of around 1400 PSI Per BH #. Thus the pure lead with BH # of 5 would deform at about 7K psi. Another thing of note is in measuring the hardness the load is applied to the ball ( for BH) & held for a prescribed interval. Full deformation is not absolutely Immediate. This is why LUP differs from true PSI, the time interval. If loading to the same ballistics with Red Dot & Unique as mentioned Red Dot would produce the higher pressure, but Unique would have a longer time interval. Assuming that both were producing a pressure above the yield point of the alloy being used the pressure vs time would to some extent at least be off-setting elements.
Unfortunately most of us do not have the ways & means of truly doing the Exhaustive Testing which would be required for Absolutely Conclusive data so we just struggle along as best we can. We thus apply what seems reasonable to our conditions.

Alliant pressure-time curve for 1 1/8 @ 1200fps 12g

Alliant e3 - 17.2 grains = 10,950 psi
Red Dot - 18.3 gr = 10,300 psi
Green Dot - 21 gr = 8900 psi
Unique - 22 grains = 8900 psi
Green Dot and Unique pressure curves are indistinguishable.
See - http://www.shotgunworld.com/bbs/viewtopic.php?f=13&t=405370



Pressure-distance

It might be a good thing that lead does not squash flat instantly.

Using an online calculator going from a standing start to 333 m/s (close to 1000fps) in 7" or .00125 second returns... get this...

27,165 G