I read the other day that recoil is similar, given the same bullet weight and the same velocity regardless of calibre. If this theory is correct then a 140gr bullet at 3000fps out of a 7mm-08 and a 140gr bullet at 3000 fps out of a .300 win. mag. should generate the same amount of recoil, given identical rifles are used. Does anyone know if this is correct? Given my limited knowledge of the laws of physics this does sound reasonable, however, given my limited experience with firearms this doesn't seem possible. Anyone ever done a test?

Recoil also depends on how much powder is burned to propel those bullets. The more gas, the greater the amount of 'ejecta' (stuff that comes out of the muzzle).

If equal amounts of powder producing equal gas columns propelled bullets of equal weight at the same velocity out of rifles of identical weight, then recoil would be the same. I think.

George

George is correct, you also have to figure in the weight of the powder charge. I think that the "total force" formula is (Bullet weight plus one half powder weight) X (velocity) squared. Then you factor in the weight of the rifle to calculate free recoil energy of the combination. In your example, recoil would be equal if both use the same weight powder charges to achieve those velocities, but I'd bet the 300Win uses more powder, and has higher recoil....

Bill

George and Bill are right: the weight of the powder charge also figures in the ejecta, the stuff being ejected from the muzzle.

If you look in the Lyman reloading manual, there is an article that contains a discussion of recoil and of the factors entering into computing it, as well as a formula for computing it. There, if I remember correctly, the figure of 4700 f.p.s. is used for the velocity of the powder ejecta. It claims that the velocity of the escaping powder gasses is the same -- or nearly enough so that one can assume that it is the same for computational purposes -- regardless of what powder is used. But the weight of the powder is an important element in the computation. If you were computing recoil for shotgun loads, you'd have to also include the weight of the wad(s) as part of the bullet (shot) weight in doing this computation.

As you are probably already aware, there's also a substantial difference between computational recoil and perceived recoil.

Perceived recoil is influenced by many factors, among them the shape of the stock and the way the gun moves during recoil, the intensity of the sound of the shot, your expectation about the recoil, the shooter's attitude [e.g., seated at the benchrest, prone, standing, etc.], the way the shooter holds the gun [lightly or tightly, etc.] when firing, the shooter's training or experience, the medium between the gun and the shooter [i.e, steel butt plate, plastic butt plate, recoil-absorbing pad, etc.], the amount of clothing worn by the shooter, whether the shooter is attending to the shot or attending to a hunting situation [you usually notice the kick of the gun much more at the benchrest than when firing at a game animal], and so on.

Supposedly, also, there's a factor that we might call the velocity of the recoil: some guns or calibers seem to strike you with a sharp hit, while others give something that might be described as a longer-duration push.

[ 07-09-2002, 23:31: Message edited by: LE270 ]

Yes. Recoil is determined by the energy generated, and the velocity of the recoiling rifle. That's why light rifles feel like they are kicking harder than a heavy one. They come back faster.
All things being equal, the heavier the powder charge, the more recoil. When reloading for handguns, for instance, I like the faster powders, if they can safely give the desired velocity. They recoil is less. E

Here are the basic theories on primary (bullet) and secondary (gas) influences on rifle recoil:

http://www.bsharp.org/physics/stuff/recoil.html

Here's a link to a recoil calculator:

http://www.handloads.com/calc/recoil.htm

Hope it helps,

Bill

Since we're talkin recoil....

Maybe this is common knowledge, or maybe I'm high, but I'd swear that the recoil is sharper with revolver and shotgun loads that have fast powder. The slower powder feels nice and smooth in comparison. I also prefer the deeper/softer sound of slow powder. Because of those reasons I've always spent the extra $$ for the slowest powder.

I belive that formula for recoil energy factors powder weight as 1.5 times and not one half. Thus with typical loads a .300 mag would kick harder than a 7mm/08 with the same net velocity at the muzzle.

I always felt that recoil velocity hurt a lot. I think some of the worst kickers for what you get are the .300 Magnums and I have two of them!