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

"...faster burning powders require less powder for the same velocity, but you pay for that with higher pressures, and let me assure you - a higher pressure load - even at the same velocity and the same payload - recoils more than a lower pressure load."

Nick Sisley
Ruffed Grouse Society magazine
Spring 2010

Nick Sisley is full of crap! Less powder produces less recoil. Pressure is not in the equation, powder weight is. All this, assuming the same velocity and payload, they are also in the equation

One would think that this would be the case but it does not seem to uniformly so. Apparently the situation is a matter of perception, with some people perceiving "quick" recoil a bit less profoundly than the "slow" kind and others "preferring a push to a jab".

FWIW, I tend to agree with Sisley. Perhaps this might have to do with the fact that I am "generously proportioned" and may "soak up" recoil that thinner types might "get out of the way of". But, who knows?

As I understand it, there have been studies that indicate that there is little "objective" evidence that "fast" and "slow" versions of the same loads recoil significantly differently. The jury still seems to be out, however.

Slow day, huh Mike?

Please see my previous comment.

While powder is a part of the "ejecta" helps to produce recoil I doubt very much that a grain or two either way would make a significant difference. In terms of "equation", except for the above consideration of Newton's Second Law I doubt very much that enough is known about the relevant variables of perceived recoil to have valid "factors", much less an "equation"...""crapful" assertions notwithstanding.

I was of the opinion that ejecta weight and muzzle velocity are the only factors in total recoil force. Am I wrong? It is obvious to me that increasing a 500 to 600 grain ejecta by 2 grains of powder doesn't change much of anything. I don't know how much a wad weighs, but an ounce of shot weighs 437 grains.

Bill is correct that weight and velocity determine the energy which goes back against your shoulder, but that amount of energy delivered to your shoulder can be delivered as a "punch" (hot powders) or as a "Push" (slow powders). It has been my experience that for a given velocity, you need more of a slow burning powder than a fast powder. I suspect that promotional shells ("Wally World" as an example) have small amounts of very hot powders. Several implications - costs less to produce those shells, more of a "Punch", and for some people, the perception that those shells are hard hitting, and therefore "good" shells.

The British gun guru Gough Thomas ran a blind test of powders with different burn rates, all else remaining equal. I'm away from my copy of his book at the moment, but if I recall correctly, everyone involved in the test chose the slower burning powder as having greater recoil. Thomas theorized that this was due to the shorter time period one felt the recoil with the faster powders.

If you plot a recoil force/time curve, the total energy under the curve will be the same for fast vs. slow powder that produces the same velocity.

Since the peak pressures are different, acceleration of the projectile will differ if internal ballistics were measured. That's straight forward pressure acting on the base of the bullet to accelerate it. If you have pressure values and bullet base area and weight, you can calculate the force applied to the base of the bullet. If you believe Issac, there is a corresponding reaction of the gun, with equal force pushing the gun in the opposite direction.

The physics say that there will be a higher peak recoil force for a higher peak pressure, all other things being equal. Can someone feel it? I'm guessing yes, if there is enough pressure difference. There's a lot of anecdotal testimony to support that people can feel differences. The gas auto is an example of approximately the same total energy under the gun recoil force/time curve, but a lower peak force at the butt, while much of the higher force is spread over a longer time. People definitely feel a difference with autos, yet the payload travels at the same velocity, for all practical purposes.

The word "recoil" is not definitive enough to understand if someone using it is talking about total energy of the gun against the shoulder or peak force of the gun against the shoulder.

The peak felt recoil and the length of that recoil force may well be different depending on the burning rate of powders. However, I am guessing that the difference is very small. Another point to consider is that the burning rate difference in acceptable loads for a certain velocity and shot load is very narrow. A 1 ounce load at 1150 fps is a great load in all weather with Red Dot. With the next vintage Alliant powder up the rate chart, Green Dot, this load is a summer load at best. We don't have all that much choice in burning rates in the light loads we like so much. In heavier loads, we are already using very slow powders, so what is this discussion really about, real life or laboratory results?