recoil, real or inferred!!!

[Doc Holliday 1950]

This is driving me crazy. I have no problem about this for myself but must get this straight for my better half. All are invited to chime in.

"Does muzzle Velocity and Muzzle Energy relate to felt recoil or kick?
Rather the lower the MV and ME the less felt recoil.
Is this correct? Of course I'm referring to the LCR for Mrs. Doc.
Sorry if this sounds stupid but I want to make sure about this. Also, does the weight of the bullet affect the two forces or is it strictly MV and ME"?

Doc

[2damnold4this]

Here you go: link

[wogpotter]

Yes.
"Every action has an equal & opposite reaction."

[BigJimP]

I look at the recoil math real simply --- as primarily a combination of :

a. weight of the gun
b. weight of the bullet
c. velocity of the round

For a given bullet ...( in 38 spl or whatever )....lower velocity and a lighter bullet for any given gun ...will give you less recoil. But the problem is - most of the time, when you look at commercial ammo - the lighter the bullet the faster the velocity.

Adding weight to a give model of handgun is not practical ...but picking a gun that is 6 - 8 oz heavier ( longer barrel, steel over alloy, etc ) usually reduces the recoil at least 15%. But you have to keep the selection in a model that fits the shooters hands....so sometimes you can't go a lot bigger...or heavier.

Reload something to suit her..../ for my young grandkids in K frame revolvers...I load a lower velocity bullet in .38 spl for them to shoot...and in general, I want to use a faster powder.../ vs what I might shoot in the same gun ( in a hotter .38 spl or even a .357 Mag )...

[Skeets]

Doc,A long time ago while trying to answer a similar type question for me a man said:"You don't have to be an electrician to turn on the lights;"Just move the switch!"Knowing this,the answer is YES.

[Doc Holliday 1950]

Got it.
Thanks!

[tallball]

IMHO the shape of the grip, the size of the hand, and how the two of them interact is a very important factor. Several times I have changed grips with the result that the felt recoil changed significantly.

[Mike_Fontenot]

Does muzzle Velocity and Muzzle Energy relate to felt recoil or kick?

IMO, total recoil most closely correlates with momentum. You can calculate momentum for comparative purposes as

P = 4.4 M*v (in lb-msec)

where M is bullet mass in grains, and v is muzzle velocity in thousands of feet per second. (I.e, for 1200 ft/sec, v = 1.2).

Note that the units for P above are one-thousandth smaller than the standard units of lb-sec, so divide by 1000 if you want to stay standard.

Also, IMO energy most closely correlates with tissue damage. You can calculate energy as

E = 2.2 M*v*v, where E is in ft-lbs, and M and v are defined as for P.

For two cartridges with the same energy E, the one with the heavier bullet will have a higher momentum. But, for two cartridges with the same momentum, the one with the lighter bullet will feel "snappier" ... the momentum reaches its full value more quickly.

Some people seem to perceive recoil more as real total momentum, but other people seem to be more sensitive to "snappiness". An example is that 230gr .45acp's have a fairly high momentum, but fairly low energy. They produce a slower, but heavy, recoil. On the other hand, 165gr .40S&W's have less momentum, more energy, and snappier recoil. Some people perceive the .40's as recoiling more, and others perceive .the .45acp's as recoiling more.

[ADDENDUM]: One other issue: the weight of the gun doesn't change the momentum ultimately transferred to the shooter ... but it DOES affect how snappy that total momentum feels to the shooter ... a heavier gun will spread out that total recoil over a longer time interval. A heavier gun will feel less snappy for the same cartridge, and will be easier and nicer to shoot (but not as nice to carry).

[Bake]

Doc,A long time ago while trying to answer a similar type question for me a man said:"You don't have to be an electrician to turn on the lights;"Just move the switch!"Knowing this,the answer is YES.
__________________

Skeets,

"Hot Dam" you are O K ....

[old bear]

Some great answers today, and Skeets gets the put it in simple and direct terms award

My recoil rule of thumb: The heavier the bullet and the faster it travels, the greater the felt recoil.

[Doc Holliday 1950]

Yes all of you explained this and I completely understand .
Thanks everyone who both posted online and in private for all your help. My wife is going to become my shooting partner and that makes me a happy oldtimer. My original problem was I didn't realize that when we bought the LCR 357, my wife, wanted the laser grips. I used to have them on a Rossi 26 oz 2"
and there was almost "no pain" even using mag loads so I didn't give it a thought.
Now with the combo of steel/poly at 16+ ozs. it's a bit different. I shot it this week and used 38 P+ ammo and the web between my thumb and trigger tigers still is sore. Hence the frantic quest for a more forgiving load to practice on for her.
If this doesn't work, then the CT laser grips goes and the Hogue Tamer grips gets put on.

Doc

[jmr40]

I look at the recoil math real simply --- as primarily a combination of :

a. weight of the gun
b. weight of the bullet
c. velocity of the round

There is a 4th factor that must be included, the weight of the powder charge. It is not uncommon to be able to shoot equal bullet weights to the same velocity and use considerably less powder in some cases. Depends on the cartridge case design and the powder chosen.

Plug in the numbers here for actual recoil energy

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

You also have to consider recoil velocity. In other words, how fast is the gun recoiling. All things being equal heavier loads at slower speeds recoil slower and even though they may have the same recoil energy and are more comfortable.

Semi-auto guns and recoil reduction devices such as recoil pads, synthetic grips or stocks also slow down recoil velocity and will be more comfortable to shoot than fixed breach guns with more solid stocks/grips.

The wider the grip/stock you have spreads out recoil over a larger portion of your hand or shoulder. A Glock 21 in 45 ACP with its wide grip and plastic frame that flexes slightly will have much less recoil than a heavier 1911 with it's narrow steel frame.

And part of the problem is "between the ears". Often people have irrational perceptions of recoil. Some convince themselves stuff kicks a lot harder than it really does. Noise is part of this. The louder the gun is the more it convinces our brains it kicks.

A small, lightweight, short barreled revolver in a magnum chambering is the perfect storm for recoil. Both real, and imagined.

[Doyle]

There is a 4th factor that must be included, the weight of the powder charge. It is not uncommon to be able to shoot equal bullet weights to the same velocity and use considerably less powder in some cases. Depends on the cartridge case design and the powder chosen.

Jim, I would make the argument that this is not a 4th factor - but rather a factor that contributes to "c" velocity.

I would argue that the 4th factor is time as you alluded to. I.E., some bullet/powder combinations produce their energy (and therefore, recoil) over a longer period than other bullet/powder combinations. Even though mathematically the recoil energy calculated may be the same, the shooter may be able to perceive the recoil differently from the two charges.

[2damnold4this]

Different powders can produce the same velocity with different charge weights. A powder that requires a heavier charge to propel a bullet to the same velocity that a different powder gets with a lower charge will produce more recoil.

For example, a charge of six grains of powder "a" moves a 130 grain bullet out of the snubby at 800 fps. Powder "b" moves the same 130 bullet out of the barrel the same 800 fps speed but only uses 3.5 grains. Powder "a" generates slightly more recoil than powder "b".

[Doyle]

Powder "a" generates slightly more recoil than powder "b".

Powder "a" may generate more "perceived" recoil because it happens over a shorter period of time. Mathematically calculated recoil energy should be the same.

[James K]

Yes, and the reason is simply that the "M" (mass) moving down the barrel is NOT just the bullet mass but the mass of the powder gas and unburned powder as well. In handguns, the mass of the powder and gas can usually be ignored since the powder charge weighs little in comparison to the bullet (4 grains vs. 158 grains, for example). But in a rifle, where the weight of the powder is perhaps one third the weight of the bullet (50 grains vs. 150 grains), the powder charge weight adds significantly to recoil.

At this point, I know someone is going to ask what the difference is between weight and mass. Well, on earth at sea-level gravity, there is none. But in space, there is. Outside a gravitational field, an object has no weight, but it still has mass.

If we moved the OK Corral to space, the bullets would have no weight and no one would be hurt, right? Nope. The bullets would still have mass and the guys hit by them would be just as dead as they were in Tombstone.

Jim

[2damnold4this]

Powder "a" may generate more "perceived" recoil because it happens over a shorter period of time. Mathematically calculated recoil energy should be the same.

The two Jims are correct. A heavier charge of powder "a" to get the same bullet to the same velocity as powder "b" will mathematically produce more recoil. link

Muzzle brakes wouldn't work if the weight and speed of the powder charge didn't add to recoil.

[James K]

I might mention that also contributing to recoil is the "jet" effect of powder gas exiting the barrel after the bullet. That is also usually ignored but will vary with the charge and type of powder. There is also a small jet effect from the precursor wave, the air in the barrel when the gun is fired and any gas that has leaked around the bullet being pushed out of the barrel ahead of the bullet.

Jim

[JeffK]

Momentum conservation and energy are important parts, but what matters to you is felt recoil, some subjective combination of force backwards on your hand and torque of the gun about your hand.

What actually happens is, the gun accelerates backwards by force applied to the breech face. In a revolver the breech face is the frame of the gun, but in a pistol the breech face moves backwards a bit with the barrel, unlocks, and then moves back a lot by pushing against a spring. Force is change in momentum divided by the time it takes for the momentum to change, so the pistol will have a smaller force on your hand than the revolver even if the guns weigh the same and fire identical bullets, because it takes longer for the momentum to be fully applied to the whole pistol.

That's the linear part, but your hand is holding the grip, and the grip is below the barrel, so this force is also a torque through the distance of the barrel above the grip. A large offset will feel more like the gun tipping backwards than like a fastball into your palm, so generally larger guns won't slam your hands as much as smaller guns.

All this explains why my MP340 is such a beast, and my wife won't fire it even with .38 specials. It is light (high recoil energy), it is a revolver (breech face transfers the force instantly to the whole frame), and the barrel offset is small (more like a fastball into the palm).

[Buzzcook]

Mass X Velocity^2

But I've also found that a gun has more perceived recoil the louder it is and the larger the muzzle flash. Not physical or felt recoil, just how people think about it. So good ear and eye protection is a first step toward handling recoil.

[Frank Ettin]

Originally Posted by Doc Holliday 1950

..."Does muzzle Velocity and Muzzle Energy relate to felt recoil or kick?
Rather the lower the MV and ME the less felt recoil....

As long as you are taking about felt recall, it's not necessarily directly related to those measurable, physical quantities. Felt recoil can be very subjective, and factors such as the shape of the grip and the distance the axis of the bore is above the grip, and the burn rate of the propellant can affect how recoil is perceived.

On the other hand, recoil energy is a precise, physical quantity that is a function of the weight (mass) of the bullet, the weight (mass) of the powder charge, the muzzle velocity of the bullet, the muzzle velocity of the powder gases, and the weight (mass) of the gun. If you have those quantities for a given load in a given gun, you can calculate the amount of recoil energy produced when that load is fired in that gun. Note that --

• Recoil energy is directly proportional to the mass of the ejecta, i. e., recoil energy increases as the mass of the ejecta increase. The mass of the ejecta is made up of --
  
  
  • The mass of the bullet; and
    
    
  • The mass of the gases produced by the burning powder (which is directly proportional to the mass of the powder charge).
  
  
• Recoil energy is directly proportional to the velocity of the ejecta, i. e., recoil energy increases as the mass of the ejecta increase. The velocity of the ejecta includes --
  
  
  • The velocity of the bullet; and
    
    
  • The velocity of the burning powder gases.
  
  
• Recoil energy is inversely proportional to the mass of the gun, i. e., as the mass of the gun increases, recoil energy decreases.

If you're interested, you can calculate the recoil energy of a given load using the following formula¹:

WG = Weight of gun in pounds
WB = Weight of bullet in grains
WP = Weight of powder charge in grains
VB = Muzzle velocity of bullet in f/s
I = Interim number (Recoil Impulse in lb/sec)
VG = Recoil velocity of gun (f/s)
EG = Recoil energy of gun (ft lb)

I = [(WB * VB) + (WP * 4000)] / 225218

VG = 32.2 * (I / WG)

EG = (WG * VG * VG) / 64.4

Felt recoil is a subjective matter. It's how you experience the recoil, and it's really something that only you can decide for yourself.

In general, for example, a lighter, fast bullet may produce recoil energy comparable to that of a heavier, slower bullet. But the recoil energy of the load with the lighter bullet will be manifest in a shorter pulse (distributed over a shorter period of time), while that with the heavier bullet will be distributed over a longer period of time. Depending on how you, personally experience these two types of recoil pulses, one may seem greater to you than the other, even though they really have similar recoil energy.
________________________

1. This formula is quite similar to a formula for free recoil set out at http://en.wikipedia.org/wiki/Free_recoil, although I think that the formula from Wikipedia may be a little more precise based on what I've read in Hatcher's Notebook. The formula I've reproduced above, is from the Q&As at http://www.frfrogspad.com/miscella.htm (specifically the question about why some guns of the same caliber kick harder than others). John Schaefer (FrFrog) notes that, "..."4000" is the nominal velocity of the powder gases at the muzzle for commercial smokeless powder and the observed range is between 3700 and 4300 f/s. It is sometimes stated as 4700 in some sources but this is based on observations of artillery, not small arms...." The Wikipedia formula would use the actual powder gas velocity, which may not be readily available.

[Snyper]

My wife is going to become my shooting partner and that makes me a happy oldtimer.

You'd better be careful

I started letting my wife shoot some of my guns, and even put her on her first deer, and the next thing I knew she started calling them "hers" and I had to ask to use them, or buy more so I would have one to use when I wanted

[osbornk]

I don't think all of this fancy calculating and figuring means a lot. In my youth in the 60s, the gun of choice for us country folks was a single shot shotgun in 12 or 16 gauge. Some of the shotguns kicked much worse than others even when we used the same ammo. The amount of kick (recoil) felt was based on the gun (mainly stock) and the weight of the gun. My Dad had a shotgun that didn't kick really bad and I had a 12 gauge that people only shot once because it kicked much harder.

Shoot the same ammo in a LCP and a TCP and you will find a big difference in the recoil and comfort between them. They are a similar size and weight.

Shoot the same ammo in a Glock 19 and a Hi-Point C9. The much heavier Hi-Point has far less recoil than the Glock.

[dyl]

Okay now, be careful what you do with this knowledge.

If you're trying to convince her of something with these numbers and formulas, it could backfire. If she likes something, she likes it. If she doesn't, try something else. I'm still learning this the hard way because I'm stubborn and I hope I'm curable. Or at least it can be put in remission.

[tedbeau]

I understand the concept that the powder charge add mass to the equations and therefore contributes to the felt recoil, but I have a few questions.

Regarding the different in powder charge weight making a difference, wouldn't the type/formula make a difference also? If essence what I am asking is do some powders produce more energy per pound? I realize some produce their energy at faster burn rate causing a higher pressure spike, but if you measure the energy created as a function of time and pressure are all powders equal?

If you could measure the pressure a small amount of powder burned and the time it took to completely burn it all could you get something like this example?

powder A 1 grain yields 1000 PSI in .1 seconds = 1000/.1 PSI/Sec = 10000

powder B 1 grain yields 500 psi in .05 seconds = 500/.05 PSI/.05 = 10000


I understand that if you accelerate a bullet to the same speed in the same amount of time the recoil in the opposite direction should be the same. If I had two different powders like in the example above would the recoil be the same.