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Pete, my comment would have been intended to the prince, never to you. ;-)

JC


"...it is always advisable to perceive clearly our ignorance." Charles Darwin
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Originally Posted By: Chuck H
Miller,
That's like saying if the thrust of the Space Shuttle is doubled in one portion of the boost phase and decreased in another to equal the same top speed, altitude and orbit, then the ride to the crew will be the same.

Chuck;
My total point is "WE ARE NOT TALKING OF CHANGES OF THIS MAGNITUDE". Give me some firm scientific data as to just how much the acceleration rate is changed by changing a forcing cone from ½" to 1½" for instance, it most certainly will not be cut in half. To have a succesful load we must first stay within max safe pressure & second maintain an adequate pressure to insure complete combustion. Looking at an older Alliant loading guide at a 3de-1 1/8oz load for 1200 fps & using a popular hull, primer & wad, loads were given for three powders. 18grs Red dot, 19½ grs Green Dot & 21 Grs Unique. Now "In Theory" the RD load should reecoil less, because it uses a lighter powder charge, but the Unique load should "Feel" easier because it accelerates slower. Frankly I don't think if I had a box of each & handed them to you randomly where you knew not which was which, you could pick out which was which. Certainly, if that acceleration rate was changed to a significant enough degree, even though the final result (IE MV) was the same the difference could be felt. We are however not speaking of using Bullseye vs Reloader 22 or for that matter even Red Dot vs Blue Dot. RD is not suitable for a high vel 1¼oz load & BD is unsuited for a light 1oz load. As long as powders are maintained within an approriate rate for the load at hand I am reminded of two statements I have read.
1st, was made by Julian Hatcher;
"There are many things which sound real good when said Fast, that won't hold up to a thorough investigation"
2nd, I do not recall where or by whom to give credit;
"98% of advertising is not to sell the product, but to convince a person they have a problem with what they are currently using".
Most of the advertising claiming reduced recoil, without reducing the ballistics, fits both categories.


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2-p, very clarifying, thank you.

JC


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Miller,
The issue as I understood it was indeed nearly the magnitude om my analogy; a low pressure 5-6 ksi load vs. SAAMI max. I know nothing of pressures from differning forcing cones or backboring nor have any opinion on their effect on recoil. Pattern? Yes, from my direct test experience on forcing cones alone. Backboring? I have no test experience or opinions on its effects.

What I do have the knowledge that when a firearm load accelerates a given payload to a given velocity it does so over a specific time. Change the pressure but keep velocity, payload, firearm weight, etc. the same, and a different acceleration occurs (velocity/time) of the payload. If you believe 'every action has an equal and opposite reaction' you will have to accept that the gun accelerates differently as well.

I believe some of the loads being discussed in comparison, can yield enough difference in this acceleration to be detected by people. They said so. I have no reason not to believe them. I have no data to disprove them. I do have some limited experience of shooting such loads where I believed I noted a difference.

To discount the "anecdotal" experiences of people without data to refute it, itself is to say 'only what I believe is supported by hard evidence, exists' . That approach woulda prevented pretty much any advancements in any field. An open mind to the unproven is what facilitates learning more about it.

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Every powder ever made claims to kill farther, give shorter shot strings, pattern better, leave the bore cleaner and produce LESS RECOIL. If there was any truth to any of this BS, we would have come down to only one powder long ago. Trap shooters spend millions every year trying to reduce recoil. While some of them believe some of these unlikely claims, they do not all use the same powder, obviously.
Wad manufacturers make the same outrageous claims. They can't all be telling the truth, can they?
People will still believe what they want, logic and physics be damned.


> Jim Legg <

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Quote:
when a firearm load accelerates a given payload to a given velocity it does so over a specific time


Chuck, wouldn't the powder's rate of burn be at play here?

JC


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JC,
If all the other variables are held constant, that would be the only way I'm aware of to change pressure to such extremes. This is reflected in loading manuals where pressures show extremes while payload and velocity are constant.

Jim,
I think the physics behind what I've stated are pretty solid; "for every action there's an equal and opposite reaction". The differnce in acceleration of the gun has to correlate with a differnce in acceleration of the payload. If exit velocity of the payload remains the same, total energy of the firearm recoil remains the same, I've always agreed on that point. The difference of opinion here is really just about whether a 'mere human' can percieve any difference of loads where pressures go from one extreme to the other while maintaining other factors.

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Quote:
To discount the "anecdotal" experiences of people without data to refute it, itself is to say 'only what I believe is supported by hard evidence, exists' . That approach woulda prevented pretty much any advancements in any field. An open mind to the unproven is what facilitates learning more about it.
Chuck;

While what you say is all "Theoretically" true I am never-the-less for the most part unconvinced.
In a totally non-related illustration some years back I had a good friend, whom I never new to deliberately "Lie" tell me he got 5 MPG better gas mileage by removing the tailgate from his pickup truck. I have no idea as to how he derived at that figure, but am fully convinced that in his own mind, he believed it. Even though this "Theory" was firmly de-bunked in that the tailgate is running in the "Draft" area of the cab & produces virtually "NO" gas robbing drag, many companies promoted it & made many $$$$ selling mesh tailgates, to those who bought it.
If you go down to your local ammunition emporium & buy a box of 12ga SAAMI 1oz loads it will almost certainly be listed as having a 3¼ DE, giving a nominal 1290 fps MV. Most of these "Low Pressure" 1oz target loads having pressure in the 5-6K psi range will be sub-1200 fps loads. Certainly, they will have less recoil due to reduced ballistics. Another thing to be considered these "LP" loads as given in the loading manuals will have been assembled in new cases. The reloader will most likely be putting them in fired cases. Considering slightly enlarged case volume, possibly weakened crimps, a load that may well be running very close to it's bottom pressure limit for complete & adequatly efficient combustion, may very well fall short of it's stated ballistics. Thus "Until" I see evidence of two loads with X vs Y powders, loaded to "Measured" same ballistics & being fired by a group of experienced shooters under conditions where they can pick the difference without knowledge of which load they are firing, I am simply compelled to treat most statements of "Reduced Recoil" as purely anecdotal.
Incendentally, L Brown has "Quoted" Gough Thomas as "Quoting" a Major British Co (one which "Sold" shells) as running a Blind Test with a large group of shooters with two lots of shells, Slow vs Fast powder, & they "Unamiously" picked those loaded with the "Fast" powder as producing less "Felt" recoil.
"BUT" that would be those having the "Quickest Acceleration" would it not??
I know no particulars as to what actual powders were tested or just what "Extraneous" circumstances may have swayed their "Feelings".
At this point, lacking provable evidence to the contrar, I am still of the opinion that approx 98% of what one will "feel" can be determined by the actual measured recoil produced. This of course assumes all variations fired from the same gun, certainly differences in stocking etc, etc, between different guns can vary the manner in which that recoil is transferred.

Ps; Another thing which should not I think be ignored is the fact of the gun iteslf weighing so much more than the ejecta it is given somewhat of a "Flywheel" effect. While the shot is Accelerating down the bbl at a much varying rate, one feels recoil as one push. It will of course take some amount of variation in the rapidity of this push, to be detactable. Just as different people can have different senso smell, different peripheral vision etc, so can different people have different sensitivity to this "Push". I guess I can just "Count Myself Fortunate" in that if I find with a given gun I can comfortably use 1 1/8oz @ 1200 fps, then I can just randomly use loads that meet that criteria & have absolutely no need to "Sweat the Small Stuff".


Last edited by 2-piper; 09/06/08 11:09 PM.

Miller/TN
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We need to go back to first principles to understand recoil!
Newtons 3rd,law [dated 1687] States;" Every force has an equal
and opposite reaction."
Newtons 2nd; law states;"The net force on an object is equal to the mass of the object multiplied by its acceleration."
Simply stated, this means that recoil is equal to: "The mass of the charge[weight of shot+weight of gas+weight of wads] x velocity of charge." This force in turn is absorbed by the weight of the gun in reality the weight of the gun is never sufficient to absorb all of the force generated leaving the shooter to absorb the residual.

As a point of clarification pressure creates the velocity which contributes to recoil.However the equal and opposite force to pressure is the stress rise in the metal of the gun barrel.


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I still say you have to sum your forces which is conservation of momentum(assuming elastic collisions with respect to Kinetic energy), Newton's 3rd law though Newton's 1st law is for an isolated system. For conservation of momentum, the gun, powder, bullet, all are at rest; therefore, the initial momentum is Zero; therefore, the final total momentum equals zero - Hence sum your forces and equate to zero. But you can look at your losses, negative forces, like heat mass transfer to the tube, hoop stress as Mr. Hebbes noted and depending on if the diameter of the tube is less than or greater than 20 times(or whatever the definition is) the wall thickness it looks as there could be traveling bulges in forward and rearward directions which leads to barrel harmonics, possibly multi-generation, vibrating, friction because the event is going to be driven to a steady state and the environment is going to do its best to attenuate the progressive event.

Kind Regards,

Raimey
rse

Last edited by ellenbr; 09/06/08 12:46 PM.
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