doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com I read it in a magazine...

Three basic tenets of classical physics are the conservation of energy, the conservation of mass and the conservation of momentum. All of those principles play into the calculation of recoil energy.

The sum total of all the energy in the universe, kinetic and potential (stored) is constant. Energy can be converted from one form to another; in this case potential chemical energy becomes kinetic energy via heat and light (solid, liquid and gas) but it never ceases to exist.

Likewise, mass can neither be created nor detroyed.
In this case, the 20 or so grains of solid propellant (of a certain chemical composition including some liquid moisture) is converted to the products of combustion...a small amount of solids and liquids , but mostly gas. The sum of the masses of all those products is exactly the same as the mass of the powder charge, and most of it is ejected. So, yes, though a small contributor to the total, the mass of the solid powder was converted to a simialr mass of (mostly) gas and was ejected.

Dam16, thank you for the support. Shotgunjones seems to contradict his theory when he indicates that the force of the gas is the determining factor, not the initial weight of the powder. 30 grains of Unique produces more gas than 30 grains of sand. Weight of propellant seems to be out of the equation.

the delta not the total, comparing fast to slow powders. 20 grains of fast powder versus 30 of slow for e.g. the difference is 10 grains out of 437.5. that's 2.2%. a charge 97.8% of another squared in the equation is only a 4.45% reduction in calculated energy. in a 20ftlb recoil 12 ga load that's .87ftlbs. anybody that can feel .87ftlbs of recoil is spending way too much time thinking about it. even at that the weight of the total powder charge compared to the shot payload is still not of much consequence.

if anyone's interested enough to read the best thing ever written on recoil, he should get the a-squared manual and read that chapter. the different aspects of it are explained more thoroughly and - importantly - more correctly there than the over-simplified articles i've read anywhere else. i no longer have it but my recollection is one example used was a comparison of a 378 weatherby and a load in some big sharps round. both had the same kinetic energy of recoil. but due to ACCELERATION (back to force again here, not KE) the weatherby was far worse in FELT recoil because it occurred so much more rapidly.

Well Eightbore, I don't feel enlightened. Mystified might be a better term. Miller, I don't have a chronograph and even if I did, I'm not sure I'd want to replicate the beating I took. I suppose I could use a sissy bag between my shoulder and the butt.

Still, the Maxi Balls I had been using showed good contact and full engraving by the lands whenever I pulled a bullet with my ball puller. I did this often when I emptied my gun after a day of hunting in the rain or snow. And pure lead should have obturated upon ignition and gave me a perfect seal anyway. Also, I had in the past used a wad of hornets nest material under my bullets or balls because that was supposed to give a better seal and prevent blown patches.

Had I had an imperfect seal with the Maxi Balls, I would have expected fliers and poor groups. Instead, this gun and load typically would put five shots into amazingly small groups, often one ragged hole at 75 yds. from the bench, and this with open sights. It was the tighter fitting projectiles that flew high and wide, and the dispersion was like minute of basketball.

I don't really recall the gun sounding differently when firing the loads that hammered me. But you're right Miller; logically, it would take a very large increase in velocity to get the amount of recoil increase that I experienced. I can't imagine that a bit tighter seal with pure lead would give me several hundred fps greater velocity though. That load normally should have ran around 1650 fps. I have shot very warm 350 gr. loads at around 2100 fps from a .45-70 Siamese Mauser that were not nearly so uncomfortable. Of course, the Siamese Mauser did not have a thin comb and narrow curved brass buttplate, so this is somewhat subjective.

I have analyzed this experience in my mind a thousand times since it happened and have no rational explanation. I feel kinda like those guys who claim they were abducted by space aliens and forced to sleep with an alien chick to propagate their species. You kind of wish you just kept the story to yourself because no one's going to believe you anyway. No, I did NOT say I have green kids.

Your 30 grains of 'whatever' was ejected at 1200 FPS, the total kenetic energy of which is calculated by 1/2 MV2. There is an equal and opposite force. How the velocity was obtained is not relevant.

Even an airgun has propellant ejecta, since a large mass of air exits the muzzle. Nothing changed state in that case, but the expanding air has mass just like powder gasses.

Consider this: Newton's law of physics; equal and opposite reaction; ejecta goes out the end of a 30-inch (2.5-foot) barrel @ 1,100 fps means it accelerated from zero at a rate to achieve 1,100 fps muzzle velocity at some rate of acceleration--but of necessity averaging 550 fps in the barrel.

Query: Does rate of burn really matter?

Assuming 1,100 fps at point of exit, 1,100 fps versus 2.5-foot barrel length means that the ejecta is going the barrel length to point of exit in 1/220th of a second (twice the 1/440th of a second of the ejecta going at 1,100 fps x 2.5 feet after exit at full speed). The average person's reaction time is about 3/10ths of a second or 66/220ths of a second. The travel time of the ejecta is about 66 times faster than the average person's mind works.

Methinks that this all can be reduced down to a simple equation:

The value of BBS-BS is directly proportional the amount of T (time) times N (number of posters) who would otherwise debate the number of angles who could dance on a double-gun hinge pin. But there is some precedent for this endless spawning of red herrings:

Going back to the advent of wood-nitro powders in the 1870s and 1880s, where shooters could directly compare the old black powder of the day to the new "smokeless" powders, there was a consensus that the wood powders had less perceived recoil and were quieter. This is mulched-over in my Parker Guns: Shooting Flying... (Collector Books 2008) @ Ch. 16 "Villainous Saltpeter" where the subject is documented by period correct anecdotes published in the sporting press of the 19th Century:

November 1876, Ira Paine wrote to The American Sportsman, citing his use of Dittmar's Wood Powder: "I use Dittmar's for my exhibition shooting on the stage on account of its lack of noise and smoke..."

May 1875 in Forest & Stream a subscriber wrote: "The results of our experiments will show how Dittmar's wood powder really worked.... With four drams of black powder, the recoil was unpleasant; but with the same load of wood powder the recoil was very light..."

In other words, the issue of felt recoil with differing burning-rate loads is as old as the inception of powders that differed from black. In February I attended a Cowboy Action shoot in Texas and the "whump" of black powder was easily distinguished from the "crack" of modern loads, given the differing nature of combustion; black powder simply burns charcoal releasing the oxygen in the saltpeter while being accelerated and bound together by sulfur; Wood powders and modern chemical substitutes have a chemical reaction beyond simple burning. Consequently, burn rates of modern powders are a function of, and controlled by chemistry, whereas black powder-burn rate is controlled by quality and relative measures of the ingredients. But does all this really matter?

My point being is that felt recoil may be subjective in the shoulder of the beholder. But there can be so many other variables:

Quoting the original post: "...a higher pressure load, even at the same velocity and same payload, recoils more than a lower pressure load.

Isn't the real question: How do you achieve the same velocity of an equal payload with less pressure (pressure being the measure of total energy exerted); it takes energy (pressure) to move the ejecta the distance from breech to muzzle at a given exit fps speed (where the ejecta at once stops accelerating and begins slowing down).

Query: Doesn't the concept of fast burn/slow burn at the same exit velocity (1,100 fps) seem to defy the laws of physics?

In the final analysis, the equal and opposite reaction (recoil of an 8-pound gun)is a function of the 1 1/4-ounce ejecta weight accelerated from zero to 1,100 fps in 1/220th of a second--and thus magnified in an instant--1/220th of a second--or about 66 times faster than an average person can react to Newton's equal and opposite law of physics.

Still confused? Then let me posit the next Red Herring: How many angles can dance on a hinge pin? EDM

Would those be acute angles, obtuse angles,right angles, or spherical?

just curious if it makes a difference.

I am puzzled about all the recoil flap. This seems a simple case of acceleration rates. Faster powders have a steeper pressure curve and accelerate the charge at a higher rate. That means the gun accelerates at a higher rate too. Thump instead of relative push. So where is the mystery?
I only have to keep two powders on hand - RedDot and Unique. RedDot for everything but pigeon loads and Unique for the flyers. Thump is not an issue for me.

Works for me but YMMV of course

WtS
PS - Shotgunners are such a bunch of wimps. If they really knew anything about gunfit then recoil would be a non-issue. But OOOOH NOOOOOOO. Where is my hydraulic buffered air shock sliding comb that I would die without?

Keith, you have to be quicker on the sarcasm monitor. I didn't understand a word I read on the post in question. I think EDM has come upon something. PSI is only breech pressure. The total pressure exerted breech to muzzle, assuming identical MV and projectile mass, would be identical.

Bill: Whatever was in the barrel before you pulled the trigger and is not there about 1/220th of a second after you pulled the trigger is ejecta. Look at the illustration on p.121 of Parker Guns: Shooting Flying and notice the differing volumes of black powder, bulk wood powder, and dense nitro powder. To the extent that these powders vaporize and leave the barrel they are ejecta as much as the wads and shot, but in proportion to relative powder weight not volume. EDM