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

Seems like I've been reading Nick Sisley since I was in my teens, and got to go shooting with him to Argentina a few years ago.
Stand-up guy, I'd believe him.
I always felt AA'a had too much recoil.

Compared to what? Remingtons? Maybe it's the letters, two A's might just naturally produce more recoil than 1 R, or maybe an STS. Of course, that's only by the more perceptive, among us.

How do you assume different accelerations? Different peak pressures aren't an assurance of that.

The discussion is predicated on identical kinetic energies...same mass, same terminal (muzzle) velocity, say 1200 fps. For one mass to accelerate 20% faster than the other, yet exit at the same 1200 fps suggests one load either 1)reaches 1200 fps somewhat sooner in the barrel, then remains essentially constant until exit or 2) the two loads reach different max velocities (>1200 fps) at different points within the barrel then slow down to exit coincidentally at the same 1200 fps. That's an interesting concept that actually could explain one recoiling "harder" than the other....if the two 1 ounce loads accelerated to different velocities within the barrel.

But.....that being the case, a simple ballistic pendulum that responded to the peak momentum and not necessarily the muzzle velocity would demonstrate that, i.e., 2 loads with same measured muzzle velocity would move the gun by different amounts, thus having demonstrably different free recoil energies.

Mike is illustrating exactly what happens in a barrel when an identical payload is propelled up a barrel in front of two powder charges of two different burning rates. One shell reaches 1200 at the 16 inch mark, the other reaches 1200 at the 20 inch mark. At either mark, the powder is exhausted. Yup, I guess the 16 inch shell will give us more felt recoil. However, not all of us will feel it, and if the powder were any slower in the 20 inch example, it wouldn't work as well in winter. As I said in an earlier post, we will use a powder as slow as it can be and still work in cold weather. What could be simpler?

Sorry. Next time, I'll try using English.

Bill,
It's more force, not "more felt recoil".

"More force" results in "more felt recoil". Being on the receiving end of the additional force generated by the faster burning powder I'm going with "more felt recoil".

This could go on forever, since some people are talking about what a person feels and others are talking about quantifyable characteristics. The former being subjective and latter objective.

Me? I've never really been bothered by recoil on any load I've used for game or target. So, all this is academic to me.

Back at home, and found the reference to powder burn rate and recoil in Thomas' book. From the chapter entitled "Searchlight on Recoil" in "Gough Thomas' Gun Book":

"On the other hand, we have I.M.I.'s prolonged researches which I have described in "Shotguns and Cartridges", in the course of which it was found that a team of shooters, firing many thousands of cartridges loaded to give the same velocity to the same shot charge, and therefore developing the same DYNAMIC recoil, unanimously voted that the variety giving the least SENSIBLE recoil were those that, unknown to them, had been loaded with the fastest-burning powder." (Emphasis the author's.)

Thomas gives a fairly long "personal explanation"--his own theory as to why this is. In a nutshell, he feels that with fast-burning powders, "the pressure on the shoulder is becoming too fleeting for the nervous system fully to record it."

Interestingly enough, at least based on the Alliant catalog I have, it would appear that Alliant Powder pretty much agrees with Thomas. They list their powders by burn rate, from fastest to slowest. Bullseye and Red Dot are #1 and 2, respectively. #3 is American Select, #4 is Green Dot. Alliant refers to the "less felt recoil" with American Select, and "lower felt recoil" with Green Dot. Since the only really commonly-used shotgun powder that's faster is Red Dot, and since several Alliant products are slower (Unique, Herco, Blue Dot), and since they don't tout ANY of those slower powders for recoil reduction, they seem to be telling us that relatively fast-burning powders are the ones to go to, if you're looking for less recoil.

FWIW, When I first got into shooting these old, wonderful doubles, I used the highly recommended 7625 powder, because of the lower pressures available. However, I found that I could get similar low pressures with Nitro 100, one of the fastes buring powders available. The difference being: about 15 grains of Nitro 100 produced the same velocity as 24-25 grains of 7625. I was convinced I could feel more recoil with the 7625 loads. As a result of this, I've been using Nitro 100 ever since. No problems with cold weather. it doesn't get extremely cold in Southern Utah and I don't go shooting, if it does. The obvious reason, to me, for Thomas's "personal explanation" is once again, the different weights of powder charges involved. Faster burning powder requiring lighter charges. That's why it's in the recoil formulas.
Good post, Larry