Muzzle Velocity and Recoil

[OneMini]

I've been trying to figure this out and it's making me crazy.

1. Say you have two different cartridges, same caliber.

2. The bullet weights differ by a significant amount (25 grains?).

3. Powder loads are such that both cartridges exit the same revolver at the same muzzle velocity.

My question is would there be a measurable difference in the recoil impulse (not
"felt" recoil, but actual energy) transmitted to the gun?

Thanks.

 

[silentflyer]

for every action there is an equal but oposite reaction, heaver slug, more recoil

 

[arjay]

....Yes...

 

[usm1rifle]

What arjay said.

 

[UDR2]

The answer to your question is a simple one: Recoil follows the law of conservation of momentum.

Momentum of a body (such as a bullet) = its mass X its velocity. So if the velocity is the same (as your criteria clearly states) and the only thing that varies is the mass of the projectile, the greater the mass of the projectile, the greater the momentum and hence the greater the recoil - felt or otherwise. Capisce?

 

[NEURON]

for every action there is an equal but oposite reaction, heaver slug, more recoil

Succinct!Excellent.

 

[MichiganScott]

You would need more powder to push the heavier bullet to the same velocity as the lighter one. The weight of the powder is included in the total weight of the ejecta. You will get more recoil than expected from the addition of 25 grains of weight.

 

[OneMini]

Thanks for the answers. So am I correct in saying that if the powder loads were such that both bullets exited with the same muzzle energy, the recoil impulses would be identical?

 

[jonesy814]

Thanks for the answers. So am I correct in saying that if the powder loads were such that both bullets exited with the same muzzle energy, the recoil impulses would be identical?

No, heavier bullet = more recoil

 

[murphydog]

OK, the engineers and physicists here can correct me, but I think the operating principle here is kinetic energy, which is 1/2 (mass) X (velocity)2. So, if velocity for both rounds is equal, less mass will generate less kinetic energy transmitted to the gun.

"Measurable" difference in energy transmitted to the gun is another question entirely; I think this would depend on how sensitive your measuring devices are, not to mention what bullet weight and velocity. Think the difference between a 130 and 158 gr .38 Special vs. a 275 and 300 gr .375 H & H; probably more difference in energy generated with the latter example.

 

[hkcavalier]

You would need more powder to push the heavier bullet to the same velocity as the lighter one. The weight of the powder is included in the total weight of the ejecta. You will get more recoil than expected from the addition of 25 grains of weight.

Well actually, you usually use less powder as the bullets get heavier. Not an expert reloader, just getting into it actually, but the tables don't lie. I believe it has to do with the pressure spiking trying to get that heavier bullet to get moving. Too much powder = too much pressure.

I have found in my years of shooting that felt recoil has little to do with muzzle energy and a lot to do with the gun's weight and the bullet weight. Heavier bullets, even at lower velocities, seem to kick more. Heavier bullet at the same velocity will definitely kick more.

 

[BruceM]

There is a mathematical formula for calculating the free recoil of any particular round. It includes the bullet weight, charge weight, bullet velocity and the weight of the firearm it is discharged in. That said, there is a difference between free (total calculated recoil force) and perceived recoil. Perceived recoil can be affected by stock features and shape and the powder's burning characteristics including pressure peaks, when they occur and their duration among other things.

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

Wouldn't be nice if things were simple!

Bruce

 

[MichiganScott]

Well actually, you usually use less powder as the bullets get heavier. Not an expert reloader, just getting into it actually, but the tables don't lie. I believe it has to do with the pressure spiking trying to get that heavier bullet to get moving. Too much powder = too much pressure.

I have found in my years of shooting that felt recoil has little to do with muzzle energy and a lot to do with the gun's weight and the bullet weight. Heavier bullets, even at lower velocities, seem to kick more. Heavier bullet at the same velocity will definitely kick more.

You are correct for normal reloading procedures. A max load for a light bullet will use more powder than a max load for a heavy bullet for the reason you mentioned.

The OP was talking about two different weight bullets at the same velocity. The only way to achieve that is to use more powder behind the heavier bullet. This is easily achieved with less than max loads.

I load for the .375 H&H. The ME of the 270gr bullet is more than the ME of a 300gr bullet when both are at max velocity. The 300gr load will definitely ring your bell more than the 270 load.

 

[scooter123]

for every action there is an equal but oposite reaction, heaver slug, more recoil

This is only true if the muzzle velocities are the SAME. Keep in mind that Force = Mass x Acceleration and Newton"s Law is most correctly stated that for every Force there is an Opposite and Equal Force.

 

[HankG]

This is a good discussion...

You are dealing with two mechanical systems...1st overcoming the inertia of the heavier bullet versus the lighter bullet. Both start out at rest in the weapons chamber. Set two wheelbarrows side by side on the street. Fill one with dirt...heavier bullet...leave the other MT. Back up 50 feet and run up to the heavy wheelbarrow and push it. Don't stop when you grasp the handles...you will fall head first into the wheelbarrow because it has more inertia to overcome to get it moving. The opposite will be true of the MT wheelbarrow...less inertia to overcome to get it moving.....Felt recoil.

2nd...Now both bullets (wheelbarrows) are accelerating down the barrel of your weapon propelled by the gases caused by the burning powder. Inertia has been overcome and they are gaining velocity. The formula for the ENERGY at the point where they leave the muzzle is Mass of the bullet in Grains times the Velocity squared in feet per second. All the aformentioned divided by a factor of 450,400, which is a factor that turns GRAINS and FEET PER SECOND to FT-LBS. Now you're dealing with ENERGY. If the energy of the bullets are the same at the exit of the barrel, and the bullet weights are different, the velocities for the different bullets will have to be different...powder charge for the heavier bullet will have to be less than the powder charge for the lighter bullet.

 

[OKFC05]

Thanks for the answers. So am I correct in saying that if the powder loads were such that both bullets exited with the same muzzle energy, the recoil impulses would be identical?

No, the MOMENTUM is the key factor, not the energy, that is conserved, being equal and opposite.

The mass of the bullet times the speed of the bullet added to the mass of the powder gas times the speed of the powder gas must together equal the mass of the gun times the recoil speed of the gun.

The recoil speed of the gun is what hurts your hand.

So we have all the elements that make a gun kick harder:
1. heavier bullet,
2. faster speed,
3. more powder,
4. lighter gun.

Felt recoil is highly subjective and varies from person to person.

 

[WILDPIG]

I gotta go get more coffee...

I am working up 1,000 fps 255 gr 45 Colt loads for 25-5 so this is interesting to me. Powder burn rates definately affect perceived and felt recoil. Problem is regulating all of this to end up with bullets impacting where you want since 25-5 sights are known to be too short in the front.

WILDPIG

 

[hkcavalier]

You can keep the math, my shoulder and my wrists will attest that slower, heavier projectiles have more felt recoil than lighter, zippier ones. Example: my .45-70 vs. my .308. ME is similar, gun weight is similar, no one in their right mind will say that the recoil is similar. Felt recoil on the .45-70 is much greater. You could do 12g slug vs. .308 as well, ME is similar there as well.

So, again, in my experience heavier bullets, even when moving slower, kick harder. Turn the velocity up and naturally they kick even harder.

 

[Waywatcher]

The question that's been burning in my head:

1. Take two outwardly identical guns, say two S&W M15-4s both with 4" barrels.
2. Use the same load in each one.
3. Chronograph the loads, and discover one gun shoots 50fps faster on avg.

Does the faster gun have more recoil? Why or why not?

Anyone know?

 

[dla]

I've been trying to figure this out and it's making me crazy.

1. Say you have two different cartridges, same caliber.

2. The bullet weights differ by a significant amount (25 grains?).

3. Powder loads are such that both cartridges exit the same revolver at the same muzzle velocity.

My question is would there be a measurable difference in the recoil impulse (not
"felt" recoil, but actual energy) transmitted to the gun?

Thanks.

Yes.

I can't stop there because the message would be too short so I had to type this sentence