Doug Ridley
New member
What has the most felt recoil, a nine mm or a 380?
Recoil
- Thread starter Doug Ridley
- Start date
stinkeypete
New member
First, we should discuss some physics terms:
Momentum = Mass (of the bullet) x Velocity
Jerk = Mass x acceleration of the Acceleration (or the derivative of acceleration velocity)(in a car.. when your head rally snaps back when your friend burns rubber)
Higher order effects include the shape of the acceleration curve
So the same momentum transfer might be felt by a big cuddly bear hug (heavy and slow) as lighting off a .454 Casull (light and fast).
Then there are old fashioned rubber shotgun pads that spread out the impulse (the shape of the momentum transfer) but absorb very little energy by converting the recoil to heat… and isomer pads that technically do absorb the mechanical energy and turn it into heat.
What we feel as recoil will depend on the amount of momentum transferred, the shape of the transfer over time (lighter and faster, like .357 Max may feel “snappy” or “slappy” while big bore revolvers with slow but heavy bullets, resulting in the same momentum, feel “pushy”), mass of the pistol held in hand, how well the grip fits the hand, the bore axis of the pistol (push vs twist), and the method of cycling the action.
The same semi-auto gun with the action welded shut will have more perceived recoil than if the action is free to cycle, slowing the impulse to the hand in the shape over time of the event.
So, .380 vs 9mm… we have to ask “for what ammunition”? Buffalo Bore .380 might push the same bullet faster than a 9mm plinking load. (You can buy such stuff.)
Then you need to know the weight of the guns. My Bersa Thunder is fairly stout, but not as heavy as some of the all steel .380s of the WWI / ww2 era.. and some of the little pocket 9mms are way too light for me to want to fire off!
My Bersa uses a blowback design, while most all 9 mms and most .380s use a moving barrel design.
The easiest answer is, the smaller the pistol, the more it kicks.
The S&W .380 EZ is not a pocket pistol. It’s got some heft. It’s got a good action and has very manageable recoil. The same gun, chambered in the average 9mm ammo, will kick more.
A CZ 75 SP-01 weighs 41 oz (2.6 pounds) will kick less.
If recoil is a big concern, the S&W .380EZ is widely admired as a serious pistol. It’s large enough to provide good grips, heavy enough to control recoil, not a blowback operation so more perceived recoil is absorbed, yet small and light enough for easy carry. Especially with modern ammo, .380 is no joke. Someone will pipe up that they think it’s wimpy and only 9mm will work. I challenge such a man to let their angry girlfriend shoot them with a .380 as a YouTube challenge. They will be sent to the same hospital or morgue as if they were shot with a 9mm, depending on how good a shot the woman is in either case. Disclaimer: don’t shoot people with guns, it will kill them.
Personally, I love the inexpensive and excellent Bersa Thunder. It’s a bit bigger, heavier, and the blowback operation is super simple and reliable although it takes some minor experience and hand strength.
Momentum = Mass (of the bullet) x Velocity
Jerk = Mass x acceleration of the Acceleration (or the derivative of acceleration velocity)(in a car.. when your head rally snaps back when your friend burns rubber)
Higher order effects include the shape of the acceleration curve
So the same momentum transfer might be felt by a big cuddly bear hug (heavy and slow) as lighting off a .454 Casull (light and fast).
Then there are old fashioned rubber shotgun pads that spread out the impulse (the shape of the momentum transfer) but absorb very little energy by converting the recoil to heat… and isomer pads that technically do absorb the mechanical energy and turn it into heat.
What we feel as recoil will depend on the amount of momentum transferred, the shape of the transfer over time (lighter and faster, like .357 Max may feel “snappy” or “slappy” while big bore revolvers with slow but heavy bullets, resulting in the same momentum, feel “pushy”), mass of the pistol held in hand, how well the grip fits the hand, the bore axis of the pistol (push vs twist), and the method of cycling the action.
The same semi-auto gun with the action welded shut will have more perceived recoil than if the action is free to cycle, slowing the impulse to the hand in the shape over time of the event.
So, .380 vs 9mm… we have to ask “for what ammunition”? Buffalo Bore .380 might push the same bullet faster than a 9mm plinking load. (You can buy such stuff.)
Then you need to know the weight of the guns. My Bersa Thunder is fairly stout, but not as heavy as some of the all steel .380s of the WWI / ww2 era.. and some of the little pocket 9mms are way too light for me to want to fire off!
My Bersa uses a blowback design, while most all 9 mms and most .380s use a moving barrel design.
The easiest answer is, the smaller the pistol, the more it kicks.
The S&W .380 EZ is not a pocket pistol. It’s got some heft. It’s got a good action and has very manageable recoil. The same gun, chambered in the average 9mm ammo, will kick more.
A CZ 75 SP-01 weighs 41 oz (2.6 pounds) will kick less.
If recoil is a big concern, the S&W .380EZ is widely admired as a serious pistol. It’s large enough to provide good grips, heavy enough to control recoil, not a blowback operation so more perceived recoil is absorbed, yet small and light enough for easy carry. Especially with modern ammo, .380 is no joke. Someone will pipe up that they think it’s wimpy and only 9mm will work. I challenge such a man to let their angry girlfriend shoot them with a .380 as a YouTube challenge. They will be sent to the same hospital or morgue as if they were shot with a 9mm, depending on how good a shot the woman is in either case. Disclaimer: don’t shoot people with guns, it will kill them.
Personally, I love the inexpensive and excellent Bersa Thunder. It’s a bit bigger, heavier, and the blowback operation is super simple and reliable although it takes some minor experience and hand strength.
Last edited:
Force = mass x acceleration
Jerk = da(t)/dt, or the derivative of acceleration with respect to time
Sent from my iPhone using Tapatalk
Jim Watson
New member
I have always heard of the derivative of acceleration called "surge". But mostly in SF with characters more bothered by surge nausea than free fall.
Jerk/surge and its derivative were developed in Davis Mechanics and said to be the basis of operation of the Dean Drive.
Jerk/surge and its derivative were developed in Davis Mechanics and said to be the basis of operation of the Dean Drive.
stinkeypete
New member
Sorry, my typo. Writing on little screens is bad for me!
F=ma and kinetic energy is mv x v…
What I’m trying to get at is that the effect we feel is how we absorb the momentum. Yeah, yeah.. I know. But it’s also the shape over time of how that momentum is transferred.
This is why it irks us so much when a bad guy in the movies is tossed across the room and against a wall like a rag doll by being hit by a bullet… he is hit by a bullet. Momentum is conserved. The bad guy feels the momentum in exactly the opposite direction of that experienced by the shooter, provided the bullet doesn’t penetrate. But…
The energy per square inch (to be all Murrican about our units) is much higher on the receiving end… just like a woman can do serious damage wearing spike heels on a wood floor where a heavier man in flat shoes won’t.
I used to have Sharp physics. Now I’m old and crusty.
The experience of shooting similar Glocks in 40, a long slide Glock in .40, and similar frame in 9mm simply has to be felt… like the difference in types of underwear.
.357 Maximum, reloading with similar kinetic energy but big variations in bullet weight (from the same Contender) was another very interesting summer project. Conclusion… hyper fast .357 HURTS your hand! Ow! sLAP!
I know I prefer heavy slugs going slower. Push vs slap.
F=ma and kinetic energy is mv x v…
What I’m trying to get at is that the effect we feel is how we absorb the momentum. Yeah, yeah.. I know. But it’s also the shape over time of how that momentum is transferred.
This is why it irks us so much when a bad guy in the movies is tossed across the room and against a wall like a rag doll by being hit by a bullet… he is hit by a bullet. Momentum is conserved. The bad guy feels the momentum in exactly the opposite direction of that experienced by the shooter, provided the bullet doesn’t penetrate. But…
The energy per square inch (to be all Murrican about our units) is much higher on the receiving end… just like a woman can do serious damage wearing spike heels on a wood floor where a heavier man in flat shoes won’t.
I used to have Sharp physics. Now I’m old and crusty.
The experience of shooting similar Glocks in 40, a long slide Glock in .40, and similar frame in 9mm simply has to be felt… like the difference in types of underwear.
.357 Maximum, reloading with similar kinetic energy but big variations in bullet weight (from the same Contender) was another very interesting summer project. Conclusion… hyper fast .357 HURTS your hand! Ow! sLAP!
I know I prefer heavy slugs going slower. Push vs slap.
No worries. I actually went back and checked the formulas because it’s been a while since I had general physics. My memory isn’t exactly great.
Sent from my iPhone using Tapatalk
Jim Watson
New member
It ain't a semiautomatic pistol, but back when really good breechloading shotguns were getting on the market, there was much thought given to "gun headache." Ballistic pendulums were used to measure both shot momentum/velocity and gun recoil.
It was then thought that recoil velocity was the figure of merit for felt recoil.
Gunmakers concluded that the game gun should weigh 100 times the shot charge, sometimes simplified to 6 pounds per ounce of shot, so a typical 1 1/8 oz 12 ga load should be comfortable in a properly stocked 7 lb gun. A lot of Britishers shot 1 1/16 oz and carried 6 1/2 lb shotguns.
It was then thought that recoil velocity was the figure of merit for felt recoil.
Gunmakers concluded that the game gun should weigh 100 times the shot charge, sometimes simplified to 6 pounds per ounce of shot, so a typical 1 1/8 oz 12 ga load should be comfortable in a properly stocked 7 lb gun. A lot of Britishers shot 1 1/16 oz and carried 6 1/2 lb shotguns.
Aguila Blanca
Staff
This does not compute. The energy per square inch is the same in all directions at the point where the action starts -- in the cartridge. One of the measures of reloading force is psi -- pounds per square inch.stinkeypete said:
The portions of that energy that are directed outward to the sides (radially) to to expending the case wall. That's restrained by the chamber. then there's the forward and rearward components. They are, for most practical purposes, the same. (Yes, they differ by some thousandths of an inch, but basically the bullet diameter is of the same order of magnitude as the case head diameter). So if the ignition of the round develops a peak pressure of (pick a number) 15,000 psi, that's 15,000 psi in all directions.
If we take a 9mm cartridge and use a nominal diameter of .356 inches, the cross-sectional area is pi x r^2 = .0995 square inches. Again assuming that the case head is pretty much the same diameter (and, therefore, the same area) as the bullet, the force will be 1492.5 pounds both forward and rearward.
Where your analogy of the shoes fails is that the energy per square inch isn't the same. A spike heel might have a diameter of a half inch, so the area of the heel would be only .196 square inches. The heel of a man's shoe could easily measure 2" x 3", for an area of 6 square inches. So if you compare a woman weighing 100 pounds and wearing spike heels to a man weighing 200 pounds and wearing clodhoppers -- the woman will produce a pressure of 510 psi on her spike heel, whereas the man will produce a pressure of 33 psi distributed across the heel of his clodhopper. The man's weight exerts twice the force, but produces 1/15th the pressure.
The "felt recoil" perceived by your hand can be quite a lot different than the actual, physical recoil impulse you might calculate. It's not quite obvious why this is.
In my experience, blowback .380's typically have a more unpleasant felt recoil than a locked-breech 9mm. But in an otherwise identical gun, the .380 will be more pleasant to shoot.
In my experience, blowback .380's typically have a more unpleasant felt recoil than a locked-breech 9mm. But in an otherwise identical gun, the .380 will be more pleasant to shoot.
Recoil in the sense of conserved momentum is easy to calculate, but recoil in the sense of "How much will I feel this when I shoot it?" is harder.
Blowback actions, tend to have more felt recoil than one would expect from the momentum calculations, and there are still some blowback .380ACP pistols out there.
As has been mentioned more than once already, you have to compare similar designs if you want to use conserved momentum to get a good feel for how it's going to feel.
Blowback actions, tend to have more felt recoil than one would expect from the momentum calculations, and there are still some blowback .380ACP pistols out there.
As has been mentioned more than once already, you have to compare similar designs if you want to use conserved momentum to get a good feel for how it's going to feel.
He's talking about recoil energy, you're talking about pressure.
What's your intended use?
My LCP II is snappier than my Glock 30S. One handed, I'd rather shoot the G30S. However, if there is a .45ACP the size of an LCP II, I'd rather shoot the .380! My G19 is the easiest to shoot of the 3, but sometimes, you need something extremely discreet like the LCP II. A Shield EZ 380/Bursa/Beretta 84 would be the easiest for all day shooting of a cartridge that nowadays is capable of stopping a threat with the right SD ammo.
My LCP II is snappier than my Glock 30S. One handed, I'd rather shoot the G30S. However, if there is a .45ACP the size of an LCP II, I'd rather shoot the .380! My G19 is the easiest to shoot of the 3, but sometimes, you need something extremely discreet like the LCP II. A Shield EZ 380/Bursa/Beretta 84 would be the easiest for all day shooting of a cartridge that nowadays is capable of stopping a threat with the right SD ammo.
The only .380 I ever owned was gone many years earlier.wild cat mccane
New member
The DB9 9mm is the exact same size as the LCP.
The DB9 isn't pleasant.
The DB9 isn't pleasant.
Kel-tec P32, .32ACP, polymer lightweight skinny grip is unpleasant to shoot.
Compared to CZ-83 in .380, steel frame doubles stack (moderately wide grip) much more pleasant though heavier.
The P32 is one of the reasons I haven't looked at any of the similar polymer .380s.
PS: For those that may consider the above "wimpy", the .357, .41 magnum, .45 Colt or ACP full-power loads in the right size pistol are not an issue. It is the skinny grip concentrating recoil in a small area that I find uncomfortable.
Compared to CZ-83 in .380, steel frame doubles stack (moderately wide grip) much more pleasant though heavier.
The P32 is one of the reasons I haven't looked at any of the similar polymer .380s.
PS: For those that may consider the above "wimpy", the .357, .41 magnum, .45 Colt or ACP full-power loads in the right size pistol are not an issue. It is the skinny grip concentrating recoil in a small area that I find uncomfortable.