How does bullet weight affect recoil?

[gofastman]

I read in a recent thread that some PD went to .40 135G loads to reduce recoil, this didn't make a whole lot of sense to me.

I was under the impression that a rounds muzzle energy had the greatest effect* on recoil (see Newton's 3rd law)
also, when I shoot Doubletap's 135g 10mm loads (767 ft.lbs) I feel a 'ellova of a lot more recoil than I feel from their 230g hardcast loads (641 ft./lbs)

So, does bulled weight have any effect* on recoil?


*this is off topic, but is is it grammatical correct to use affect or effect in this situation

 

[Echo9]

Yes.

As I understand it, the mass of the ejecta adds more recoil to the shot than the ejecta's velocity.

Imagine throwing a tennis ball as fast as you can. Now imagine throwing a brick as fast as you can. You'll certainly throw the tennis ball a lot faster than the brick, but in which case will there be more force acting upon your arm? The brick.

Someone correct me if I'm wrong, but I'm also reasonably sure that velocity accounts for a round's snappiness, and it's mass accounts for it's push. Think of the snap of a light 9mm versus the push of a heavy .45 acp.

"Effect" is a noun. "Affect" is a verb.

"So does bulled weight have any effect on recoil?"

That's correct.

"So does bullet weight affect recoil at all?"

So is that.

 

[Charles Davis]

Hi guys
The laws of physics apply. F=MVsquared
To calculate the power of a bullet strike in ft/lbs
Force (striking)=Mass(weight of bullet) times Velocity squared ( in feet/sec)
The FBI suggests you need a minimum of 400 ft/lbs for self defense
As far as recoil - for every action there is a opposite but equal reaction.
As the bullet shoots out of the barrel you get a equal reaction (recoil)
Your weight and the weight of the gun obsorbs the recoil.
Simply put, the force coming out of the barrel gives you recoil. More force, more recoil.

 

[TexasBen317]

Awww, to hell with all the fancy math..Yep, a heaver bullet kicks more than a lighter one.

Try this to prove it.. Shoot a 30-06 with a 150 grain, then shoot it with a 180 or 220 grain. That will answer your question

 

[gbw]

IIRC (I may not)

(MVsquared)/2 is kinetic energy.

Force = mass * acceration
or
Force = mass * (change in velocity) over time, f=d(mv)/dt

Anyhow...a heavier bullet will produce more recoil (rearward acceleration of the gun) only if it is shot (accelerated forward) fast enough.

Usually with factory loads they are, so it seems a heavier bullet always produces more recoil, but there' no reason that they must.

 

[brickeyee]

Recoil is based on mometnum, not energy.

Mass x Velocity

There is also an effect in 'jerk' (rate of change of acceleration) that makes a short sharp acceleration FEEL worse.

The differance between a shove and a hammer blow.

Free reoil energy is computed using conservation of momentum.

Mass if ejecta (bullet and powder weight) with each assigned a velocity.

The reoil velocity is thenthe ejecta momentum divided by the mass of the gun.

This is then used to create a recoil energy for the gun using 1/2 * mass gun * velocity of recoil

This is the analytic solution to recoil.

The problem is that grip design (stock on a rifle) has a great effect on the PERCEIVED recoil.

 

[teumessian_fox]

velocity accounts for a round's snappiness, and it's mass accounts for it's push

It's not "one or the other." Both variables factor into recoil.

 

[moxie]

gofastman,
Your use of "effect" in that context was correct.
Effect can be either a verb or a noun. For example you can "effect" a change to a law. In this sense it means to make a change.

 

[azyogi]

talking felt recoil or MG * VG this would be the impulse, or recoil
MG * VG = MB * VB + MC * VC
where MG = mass of the gun
VG = velocity of the gun
MB = mass of the bullet
VB = velocity of the bullet
MC = mass of the powder charge
VC = velocity of the powder charge
quoted from the ballistics section of the NRA Firearms Fact Book [third edition]

 

[Cosmik de Bris]

The laws of physics apply. F=MVsquared
To calculate the power of a bullet strike in ft/lbs
Force (striking)=Mass(weight of bullet) times Velocity squared ( in feet/sec)

Umm, no. mass times velocity squared is energy not force.

E = mv^2

Force is mass times acceleration or change in momentum with respect to time.

Momentum p = mv
F = ma or F = dp/dt

The FBI suggests you need a minimum of 400 ft/lbs for self defense
As far as recoil - for every action there is a opposite but equal reaction.

This is momentum.

As the bullet shoots out of the barrel you get a equal reaction (recoil)
Your weight and the weight of the gun obsorbs the recoil.
Simply put, the force coming out of the barrel gives you recoil. More force, more recoil.

This is momentum not force.

 

[Charles Davis]

Energy etc

Very good guys. Forgot my high school physics for a moment. Your right, It is kenetic energy. BTW, If you apply 400 ft/lbs of energy to your body, you will feel the force.
That formula is of course only one factor of felt recoil
there are many other facters on felt recoil like the rate of acceleration due to powder burn rate. Hornady I believe has a new line of reduced recoil ammunition that give the same muzzle bullet speed/energy. they do it with progressive burn gun powder.
One shotgun manufacturer (Browning I believe) has come out with reduced recoil shotguns. They use a energy obsorbing piston inside the stock area. You could say it obsorbs energy. Momentum of course is an object (bullet) tending to maintain its speed resisted only by air drag and gravity. A bullet propeled out of the muzzle has momentum. The opposite and equal energy energy pushing back on the gun is felt recoil, not momentum. Enought with the physics.
I was just trying to say that things like recoil is usually basic math plus a few extenuating items, burn rate, mechanisms etc.
May the force be with you

 

[Bovice]

I find that GENERALLY 180 grain loadings in .40 are more controllable than the lighter ones for me.

 

[glassman]

After reading all the responses, I'm more confused than when I started reading the thread. I need simple answers for my simple mind to understand. Thanks texasben for an answer I can understand without the need for texas instrument.

 

[Caliper_Mi]

One shotgun manufacturer (Browning I believe) has come out with reduced recoil shotguns. They use a energy absorbing piston inside the stock area. You could say it absorbs energy.

It does absorb energy when it compresses, but it then expends it back right away unless the piston stays compressed. What it does is reduce felt recoil by making the entire recoil process take longer.

Just to bring in more physics, this is the power that the recoil exerts on your body. (Force x distance)/time = power. The piston (or a rubber grip on a handgun) will spread the recoil over a longer time. It will also reduce the jerk that brickeyee mentioned by smoothing the impact of recoil on your body.

One could say that the slide on an autoloader accomplishes this purpose also. As the bullet leaves the barrel, the recoil energy is directed into the spring. The spring stores this energy as it compresses. Force on the grip frame (and thus your hand) is limited to F = spring rate x slide travel as the slide compresses so here is a gradual (comparatively) buildup in force. Ultimately, the entire energy of firing must be transmitted to your hand because the pistol comes back to rest in the same place as it was fired. Because this is spread out over a longer time, there will be less felt recoil.

 

[possum]

there are some smart dudes on this forum! wow all i know is that i have less precived recoil with lighter weight bullets. that is about all i can add to this disscussion.

 

[Sunray]

"...correct to use affect or effect..." Bullet weight affects the effect. And yes, the bullet weight does make a difference. So does the velocity. A heavy bullet going slow, will have less felt recoil that a heavy bullet going fast. Mind you, the handgun's grip shape and material has a lot to do with felt recoil too.

 

[philip964]

Yes Sunray has it right weight and velocity are both important but so also is the gun. The gun powder pushes the gun back and the bullet forward. Since the bullet is light compared to the gun and the body that is holding it, the bullet moves more than the gun. I suppose if you could fire a gun without holding it, we would be surprised how far it moves back, especially those light polymer models.

 

[janobles14]

lol let me nutshell it....

it takes more strength to push a heavy rock than it does a light one. your feet slide more when you try to move a heavy rock. same with bullets. heavier bullet = more felt recoil.

 

[Walkalong]

If you do the fancy math, you'll find that heavier bullets can recoil less than lighter ones, depending on the velocity. (And to some extent the powder)

I find that GENERALLY 180 grain loadings in .40 are more controllable than the lighter ones for me.

Yep. I much prefer 180 Gr for full load stuff in .40. Much less "snappy" and much more pleasant. The math can't do it all.

Anyone know the formula for "snappy"?

 

[benEzra]

Recoil is based on the momentum, not the energy, of the bullet and combustion gases. If you take a light bullet and drive it faster, you can create the same energy but less momentum, and hence less recoil.

For an extreme example, a .223 and a lightly loaded .45-70 could have the same energy, but the .45-70 would recoil much, much more.

 

[azyogi]

snappy would be VC or the velocity of the powder charge, when I shoot BP guns it's more of a shove than a snap like a smokless gun.

 

[heron]

I quit using 158 gr loads in my .357 Mag (6" GP 100) for exactly this reason; the recoil was too much for my comfort and control. I'm fine with 125 gr or so.

 

[Dr T]

The weight of the firearm has a bit to do with it. I keep a neoprene scuba weight belt around to drape over the stock of my 375 H&H when I put it on the bench.

See

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

for a handy calculator that does the math for you.