jakemccoy
Member
...still no definition
The effect of a heavier weight bullet?
- Thread starter BruceRDucer
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Vern Humphrey
Member
Don't feed the troll.
jakemccoy
Member
Vern, I went ahead and reported your posting.
Vern said:
Vern said:
Last edited:
Sylvan-Forge
Member
Gentlemen,
Let me tell a brief story about my subjective experience with recoil.
.40 cal. pistol, 135gr projectile, 6.0gr charge, 1180f/s.
Snap. Oww!
Same pistol, 180gr projectile, 5.5gr charge, 940f/s.
Shove. Ahh!
I know in my brain that there is a little more recoil impulse/energy in the heavier projectile, but the way it 'felt' was quite different. I 'feel' the 180 recoils less. It recoils less to me because the force is spread out differently over a period of time.
Powercurve if you will.
...
I've had various counter-intuitive experiences in different calibers and platforms..
If you can write a formula for your own subjective-perceived-felt
recoil, that is great, but you can't apply it reliably to other people.
So to make clear ..
There is measurable recoil - Fact.
There is subjective felt-recoil - Opinion.
..
Both are important to discuss, no?
.
Let me tell a brief story about my subjective experience with recoil.
.40 cal. pistol, 135gr projectile, 6.0gr charge, 1180f/s.
Snap. Oww!
Same pistol, 180gr projectile, 5.5gr charge, 940f/s.
Shove. Ahh!
I know in my brain that there is a little more recoil impulse/energy in the heavier projectile, but the way it 'felt' was quite different. I 'feel' the 180 recoils less. It recoils less to me because the force is spread out differently over a period of time.
Powercurve if you will.
...
I've had various counter-intuitive experiences in different calibers and platforms..
If you can write a formula for your own subjective-perceived-felt
recoil, that is great, but you can't apply it reliably to other people.
So to make clear ..
There is measurable recoil - Fact.
There is subjective felt-recoil - Opinion.
..
Both are important to discuss, no?
.
Sylvan-Forge
Member
Checking my records .. I'd say ~65% of my experiences have followed along with the various formulas of recoil (basically momentum p=mv).
YMMV, of course.
.
YMMV, of course.
.
1911Tuner
Moderator Emeritus
Yes. If the 135 at 1180 generated more momentum than the 180 at 940, it will produce more recoil momentum, and more felt recoil.
No argument there.
With an autopistol, there is a factor that is largely ignored. I noted it once, but I'll repeat it.
The recoil impulse isn't transmitted to your hand in the same way that a revolver does it because it's on a sliding rail. If the slide were mounted on a 30-foot frame rail, without a recoil spring between them...you could fire the gun and feel nothing beyond a mild push from the rail to rail friction. You get almost nothing from the internal ballistic event...or the "explosion" of the powder charge and the resulting action/reaction between bullet and breechblock. What you feel comes from the recoil spring and the slide impacting the frame. Of the two, the slide's impact generates the more
obvious.
The recoil system is a closed system...separate and apart from the main system of the bullet, barrel, and slide. The compressing spring generates a force vector between the slide and frame. As it compresses, it pushes on both with equal force. The faster it compresses, the harder it pushes.
That "Equal and Opposite" thing works backward, too.
The impact with the frame is the one that tells the tale. If the bullet is driven hard enough and fast enough to generate more momentum than the heavier bullet...the slide will have more momentum. The slide will move faster...compressing the spring faster...and it will carry that momentum to the impact point with the frame.
Increasing the spring rate won't change anything. It will slow the slide, but will generate more forward and rearward force as it compresses than the lighter spring...so it equals out. It softens the blow at impact, but is pushing harder before that impact occurs, and you're back to square one. So, it doesn't "soften" recoil so much as it changes the amount of time that the gun recoils...and thus your perception of it. Momentum is momentum and must be conserved. All a spring rate change does is to alter the amount of time that it takes to deliver the momentum to your hand. Go and fire a Browning autoloading shotgun with its long recoil operation...and then fire a pump shotgun of the same weight. The momentum is the same. The recoil impulse is the same. Only the way that the recoil is delivered to your shoulder changes.
So, felt recoil comes from momentum...not the bullet's kinetic energy. We've used the .220 Swift/.45-70 analogy to demonstrate that. You can step it up a notch and fire an 8-pound .308 rifle with a 150-grain bullet at 2800 fps back to back with an 8-pound Sharps carbine with a 405-grain bullet at 1350 fps to demonstrate it. The .308 generates some 2600 foot-pounds of kinetic energy, and clearly beats the big, slow slug...but the .308 rifle isn't at all unpleasant...while the Sharps is decidedly so after about 8 or 10 rounds.
Anyone who is within driving distance can come and try my Sharps. BYO .308 rifle. All mine weigh less than the Sharps...but they still don't kick as hard.
1911Tuner
Moderator Emeritus
Vern is a bit frustrated. Nevertheless, I shall administer discipline.
Humphrey! Drop and gimme 10. And stand up straight...and get a haircut!
You look like (expletive deleted)
Now we can all be friends again...
I agree wholeheartedly. I have posted the same thing about 155 Gr vs 180Gr for a while now.
The 180 Gr at liesurely velocities is way more comfortable to shoot, to me.
Vern may be onto something though. There has been some pot stirring here.
Vern Humphrey
Member
One, two, three, four, five, six, seven, eight, nine, ten, Ahbone, Sagent!
MTMilitiaman
Member
Airborne only does ten nowdays
I am sure my brother will be relieved
I am sure my brother will be relieved
1911Tuner
Moderator Emeritus
oorah
Vern,
I'd love to take you up on the offer to shoot with you in N.C
I can bring a few of my Sharps with me and we can have a high old time together. Shootin' Sharps makes any day a good day!
Curious, you didn't list in your post if your shooting BP or Smokeless when you talk about 8-10 rounds becoming unpleasant to shoot. I managed to break my shoulder about a year and half ago. Fell down a flight of stairs...So nowadays I'm recoil sensitive. But I can shoot my 45/90 all afternoon and feel quite comfortable if I use Fg powder and a 550gr bullet....
So what powder are you using in that puny little 45/70 with those tiny little 405 grain pills
Giz
I'd love to take you up on the offer to shoot with you in N.C
I can bring a few of my Sharps with me and we can have a high old time together. Shootin' Sharps makes any day a good day!
Curious, you didn't list in your post if your shooting BP or Smokeless when you talk about 8-10 rounds becoming unpleasant to shoot. I managed to break my shoulder about a year and half ago. Fell down a flight of stairs...So nowadays I'm recoil sensitive. But I can shoot my 45/90 all afternoon and feel quite comfortable if I use Fg powder and a 550gr bullet....
So what powder are you using in that puny little 45/70 with those tiny little 405 grain pills
Giz
1911Tuner
Moderator Emeritus
'Tain't Vern that's in NC. It's moi.
For the light, plinkin' loads, I like to use 27 gains of 2400 and a cotton filler. Velocity is a lazy 1300 fps, give or take.
For punchin' holes in Abrams tanks and downin' ICBMs...43 grains of IMR 3031 for about 1700 or so.
Remember this is a Cavalry carbinen with a 22-inch barrel. It weighs 7.8 pounds empty. If the loads listed were shot in a 10.5 pound business rifle, they'd be a lot more bearable.
For the light, plinkin' loads, I like to use 27 gains of 2400 and a cotton filler. Velocity is a lazy 1300 fps, give or take.
For punchin' holes in Abrams tanks and downin' ICBMs...43 grains of IMR 3031 for about 1700 or so.
Remember this is a Cavalry carbinen with a 22-inch barrel. It weighs 7.8 pounds empty. If the loads listed were shot in a 10.5 pound business rifle, they'd be a lot more bearable.
Sorry about that Vern thing...LOL
Ok moi,
Hmmm~~~
Ever tried say 70 grs of Fg in that gun. Was what it was originally meant to shoot. Something tells me you'd report a difference in perceived recoil if you did. Might make the difference between shootin' 8-12 rounds before it became uncomfortable and shooting around 60 rounds and stopping cause you just ran out of ammo
Giz
Ok moi,
Hmmm~~~
Ever tried say 70 grs of Fg in that gun. Was what it was originally meant to shoot. Something tells me you'd report a difference in perceived recoil if you did. Might make the difference between shootin' 8-12 rounds before it became uncomfortable and shooting around 60 rounds and stopping cause you just ran out of ammo
Giz
1911Tuner
Moderator Emeritus
Giz...I've prob'ly shot enough black powder to blow up half the world. I've broken the habit. Got too lazy to clean the flippin' things.
I do, however, very much like the Sharps 50-120 stuffed fulla Goex.
But I'd go broke payin' somebody to clean it.
I do, however, very much like the Sharps 50-120 stuffed fulla Goex.
But I'd go broke payin' somebody to clean it.
Too funny,
I am starting to realize there is something really wrong with me...I actually enjoy taking the gun apart and cleaning it. Lubing it and putting it back together...then again, I enjoy casting Minnie's and big grainer bullets. Heck, I even like lubrisizing...
Think there is any help for me
On the flip side, I shoot the snot out of my race guns ~ generally hit them with lots of non chlorinated brake cleaner, use stainless steel brushes on them, torpedo brushes in the chambers and have even used 38 brass to clean the crud out of the cylinder flutes
I'm just a contradiction of myself foolish self!
Anywhoo, I respect your opinions and will stand by my foolish BP argument that it does effect felt recoil based on the difference in the peak pressure pulse that differs to Smokeless powders...
And anyway, wheres that Smokeless moniker come from ~ Hell, Bullseye is just as bad as some of the BP substitutes...
Giz
I am starting to realize there is something really wrong with me...I actually enjoy taking the gun apart and cleaning it. Lubing it and putting it back together...then again, I enjoy casting Minnie's and big grainer bullets. Heck, I even like lubrisizing...
Think there is any help for me
On the flip side, I shoot the snot out of my race guns ~ generally hit them with lots of non chlorinated brake cleaner, use stainless steel brushes on them, torpedo brushes in the chambers and have even used 38 brass to clean the crud out of the cylinder flutes
I'm just a contradiction of myself foolish self!
Anywhoo, I respect your opinions and will stand by my foolish BP argument that it does effect felt recoil based on the difference in the peak pressure pulse that differs to Smokeless powders...
And anyway, wheres that Smokeless moniker come from ~ Hell, Bullseye is just as bad as some of the BP substitutes...
Giz
Sylvan-Forge
Member
Gimme that spoon!
1911Tuner, the 180gr load made more momentum, but it felt softer .. I understand what you mean though.
Design, spring rates, slide mass and timing .. just as you have detailed
I believe most LE loadings are 180gr, so the pistol was probably designed for 'em.
Most (65%), but not all of my records indicate p=mv. Of the actions that are manually operated, it's about 70% that agree with momentum or momentum-based free-recoil formulas.
I guess all I can conclude is momentum formulas are correct 70% of the time for felt-recoil .. or are incorrect for 30%, if I'm feeling pessimistic
Larger differences in projectile weights and/or velocities will most always allow the momentum formulas to accurately predict felt-recoil in the same weapon.
.
YMMV, of course.
.
1911Tuner, the 180gr load made more momentum, but it felt softer .. I understand what you mean though.
Design, spring rates, slide mass and timing .. just as you have detailed
I believe most LE loadings are 180gr, so the pistol was probably designed for 'em.
Most (65%), but not all of my records indicate p=mv. Of the actions that are manually operated, it's about 70% that agree with momentum or momentum-based free-recoil formulas.
I guess all I can conclude is momentum formulas are correct 70% of the time for felt-recoil .. or are incorrect for 30%, if I'm feeling pessimistic
Larger differences in projectile weights and/or velocities will most always allow the momentum formulas to accurately predict felt-recoil in the same weapon.
.
YMMV, of course.
.
1911Tuner
Moderator Emeritus
Again...when firing an autopistol, you have to take the speed/rate of the spring compressing. A faster bullet drives the slide faster...and compresses the spring faster. The only real way to get a back-to-back comparison is to fire different rounds in a fixed breech gun because the only thing that changes is the momentum. There's no reciprocal movement and no spring to factor in. You can closely duplicate the bullet mass and velocities with a .357 revolver.
A good comparison is an old M-17 Smith .45 ACP revolver vs a 1911 pistol firing the same ammunition. The revolver's recoil will be different. A little quicker...but a little "softer" in your hand.
Limit the +P stuff in those old wheelguns, please.
physics
Member
Wow... just wow. It's funny, I always manage to avoid these threads until about this time in their life... Anyways, I AM a physicist. Mechanics isn't necessarily my forte, that being solid state and e&m, but I have taken a few years of mechanics too.
1911Tuner is dead on, he even said it better than I can. Although, my brain seems to be farting, so can you show me how a faster bullet drives/compresses the slide faster?
My only addition, is that the speed of the powder burn is important in this equation (as per the original question). A slower burning powder would give a slower recoil, and a fast burning powder would give a fast recoil.
What I mean by fast and slow is that with a fast recoil, you will feel all of the force hitting you in a small time interval, and thus will feel like more. With slow recoil, it happens over a longer period of time, so it hurts less.
Kinda like the difference between jumping off a building and landing on concrete versus landing on a stunt bag made for such activities. You slow down a whole lot faster with concrete.
I do admit though, I'm not sure how much of an effect this would have. Probably not noticeable, but possibly.
1911Tuner is dead on, he even said it better than I can. Although, my brain seems to be farting, so can you show me how a faster bullet drives/compresses the slide faster?
My only addition, is that the speed of the powder burn is important in this equation (as per the original question). A slower burning powder would give a slower recoil, and a fast burning powder would give a fast recoil.
What I mean by fast and slow is that with a fast recoil, you will feel all of the force hitting you in a small time interval, and thus will feel like more. With slow recoil, it happens over a longer period of time, so it hurts less.
Kinda like the difference between jumping off a building and landing on concrete versus landing on a stunt bag made for such activities. You slow down a whole lot faster with concrete.
I do admit though, I'm not sure how much of an effect this would have. Probably not noticeable, but possibly.
1911Tuner
Moderator Emeritus
Surely. Remember that the recoil that we feel when firing an autopistol comes from the spring and the slide impacting the frame...not from the internal ballistic event like with a fixed-breech weapon.
In order for a light bullet to have higher momentum than a heavy, slower one...it has to move faster. Momentum=Mass X Velocity.
Force forward=Force Backward.
More force must be imposed in order to drive a light bullet to a high enough velocity to top the heavy bullet's momentum. i.e If a 185-grain bullet were driven with the same powder charge as is the norm with a 230...its velocity would be a little higher, but not enough to exceed the momentum of the faster bullet.
If the light bullet were loaded to equal the momentum of the heavier one...the recoil impulse would be the same. The forces involved may be higher in order to achieve that...but my bet is that it would be undectable by the human hand. A little math and a bit of handloading will reveal much. Yep. Done it.
The slide's mass and the spring's load/resistance are constant. If more force is imposed on the slide...its rate of acceleration must be higher. The spring compresses at a faster rate, and the resulting impulse transmitted to the shooter's hand BY the spring through the frame is greater.
You can achieve the same effect by using a stronger/higher-rate spring with no other changes. Install a 14-pound recoil spring and shoot the gun. Then, slip in a 20-pound spring. You'll notice that the felt recoil is quite a bit snappier...even though the slide's momentum is the same.
1911Tuner
Moderator Emeritus
Glad you brought that up.
In a pistol caliber...and even in a magnum revolver caliber...the bulk of the bullet's velocity and the resulting recoil impulse occurs early, during the rapid climb to peak pressure...probably within the first half-inch of bullet travel in the barrel.
Since Newton dictates that objects at rest tend to remain at rest...the more quickly you try to accelerate it, the harder it fights that acceleration.
Lift a 50-pound weight at a rate of 1 foot per minute...then lift it at a rate of 10 feet per second.
The frictional resistance on the bullet as it enters the rifling also works to resist...so the rise to peak pressure...and peak force...are early and fast.
What little additional bullet acceleration that comes after the peak, and during the rapid drop of pressure and force...means almost nothing, recoil-wise.
Think about it like this.
If the rule of thumb of 35 fps per inch of barrel gained or lost is accurate...and it's pretty close...
If we get 850 fps from a 5-inch barrel...and we get 35fps per inch X five...then we're getting 175 fps in the barrel. Where does the other 675 feet per second come from?
Let's get it a little closer.
If the greatest percentage of the bullet's final velocity occurs in the first half-inch...we're down to 4.5 inches X 35. That's 137 fps...leaving
713 fps unaccounted for.
Even slow rifle powders peak rapidly...probably within the first 2-3 inches of bullet travel even with the really slow powders.
So...with normal pistol powders that are suitable for a given application...is there enough difference in the burn rate between Bullseye and Unique to detect a difference? Not likely. Possibly between Unique and Olin 296 or H-110...but my opinion is that it would take a sensitive hand if both cartridges were loaded to equal pressures.
"Subjective recoil" -- a great deal depends on the fit of the gun. Drop of the comb, length of pull in the stock, balance of the firearm. All these will affect "perceived recoil."
The experience of the shooter with heavily recoiling firearms has a significant bearing on "perceived recoil." And on that note, here's a link to some yahoos shooting a 577 T Rex.
www.youtube.com/watch?v=-EVqT3XEzss
www.youtube.com/watch?v=CQJSZs-euZU
What you'll see in these clips is inexperienced shooters being tossed across the room from the recoil of this gun/load. The last shooter in one of these clips has experience shooting a gun of this caliber, and so is able to manage the recoil.
I have a .458 Win. Mag. -- 500 gr. bullet at 2161 fps. The calculated recoil is in the realm of 65 ft. lbs. in a 9 lb. gun. Nominal recoil for 30-06 is in the realm of 20 ft. lbs. 45-70 Govt. runs about 40 ft. lbs. recoil w/ 350 gr. bullet.
But because the gun fits, and is designed to shoot this caliber (Ruger No. 1 Tropical), the recoil, while significant, is not what I'd call "uncomfortable" --
But your mileage may vary.
The experience of the shooter with heavily recoiling firearms has a significant bearing on "perceived recoil." And on that note, here's a link to some yahoos shooting a 577 T Rex.
www.youtube.com/watch?v=-EVqT3XEzss
www.youtube.com/watch?v=CQJSZs-euZU
What you'll see in these clips is inexperienced shooters being tossed across the room from the recoil of this gun/load. The last shooter in one of these clips has experience shooting a gun of this caliber, and so is able to manage the recoil.
I have a .458 Win. Mag. -- 500 gr. bullet at 2161 fps. The calculated recoil is in the realm of 65 ft. lbs. in a 9 lb. gun. Nominal recoil for 30-06 is in the realm of 20 ft. lbs. 45-70 Govt. runs about 40 ft. lbs. recoil w/ 350 gr. bullet.
But because the gun fits, and is designed to shoot this caliber (Ruger No. 1 Tropical), the recoil, while significant, is not what I'd call "uncomfortable" --
But your mileage may vary.
Sylvan-Forge
Member
I have and I'm still not getting it
The 180gr @ 940 f/s using 5.5gr charge shows greater recoil impulse, firearm velocity and free recoil energy than the 135gr @ 1180 using 6.0gr charge ...
Here's the written formula I used:
http://www.loadammo.com/Topics/August01.htm
Yields the same as the calculator that rcmodel linked:
http://www.handloads.com/calc/recoil.asp
.
Only way I can fathom it feeling less is that it takes the 180gr bullet a longer time to leave the barrel than the 135gr even though the slide (after unlocking) is being driven back with more oomph.
.
1911Tuner
Moderator Emeritus
I dunno quite how to explain it.
First, the calculation of bullet/recoil momentum is far too complex. The IDPA/USPSA's "Power factor" is no more than a measure of momentum...or how far the bullet will move a ballistic pendulum. Grain weight times velocity divided by 1,000 is the formula. Using this, the venerable .45 hardball load of 230/800 fps gives us a power factor of 184, and the same bullet at 750 fps just squeakes over the line with 172.
Using the same calculation, your 135/1180 churns up a power factor of 159. It doesn't make major, but it doesn't miss by much. The 180/940 does a little better at 169...barely missing major.
So, we have a little more momentum with the slower, heavier bullet...but not enough to feel any real difference on the other end of the gun. At least, not in my hand. Doing a side-by-side comparison of my 200 grain SWCs at 800 fps with my 230s at 800...I can tell a little difference if I'm really paying attention...but nothing like being reported in the .40 caliber 135/180 comparison.
So, there's obviously something else going on. That something is the slide's reciprocation and changing center of gravity. The speed of the recoil spring's compression, and the slide's impact with the frame.
Many people mistakenly believe that the recoil that the feel when firing an autopistol is the result of the actual action/reaction event between the bullet and the breechblock. It's not. What generates the felt recoil is the action/reaction event between the slide and the frame via the spring and the slide's suddent stop against the frame...and then we feel yet another one as the spring accelerates the slide back to battery. All that violent slam-bangin' around fools our mind into thinking" "Wow! This thing really kicks! It must be some kinda pow'rful!"
If you can arrange to shoot the same two rounds in a revolver, your brain won't be quite as impressed because it's all over with in one quick punch.
Then there's the matter of the mass of the powder charge. The 135/1180 uses a heavier charge...adding to the total mass of the ejectiva. That adds to the recoil momentum and energy by the weight of the powder charge in grains. There's also the matter of the pressures. Most often, the lightweight scrreamers are loaded to higher pressures. +P if you like. That accelerates the powder gasses...adding to the effect.
Incidentally, the heavier bullet's dwell time in the barrel has almost nothing to do with felt recoil in a pistol...and little more in a revolver. A rifle wth a 22-inch barrel...sure. The short recoil system of the 1911 and probably also the Glock, etal...only gets a recoil impetus during the first 1/10th inch or so of slide travel. At that point, the bullet is gone, and can't generate any more "push" through the force vector...and the slide continues on via the momentum conserved during that time. The few milliseconds' difference in dwell time between the two bullets is pretty much meaningless.
What is a real factor is the speed at which the slide compresses the spring. Newton's 1st law of inertia mandates that it takes more force to get an object moving than it takes to keep it moving, or even accelerate it to a higher velocity. We've seen that the greatest percentage of the bullet's final velocity occurs within the first half-inch of bullet travel. With really fast powders, it may even be less. Factoring in the bullet's inertial mass, it takes more force to accelerate the 135 grain bullet to some 970 fps...of the total of 1180...than it takes to accelerate the 180 to 730 fps, with the total being 940. The 135 grain bullet's velocity at a half-inch of travel is faster than the 180s is at the muzzle. Think about that.
Force forward equals force backward. This is Newton's 3rd law simplified. Whatever force drives the bullet is also visited on the slide. Simple physics determines that when a greater force is applied, an object of a given mass will accelerate faster than the same object with a lesser force applied. Witness that a peak pressure of 25,000 psi will produce higher velocities with a given bullet than will 20,000. Simple physics.
So...while the slide's momentum must be ewqual to that of the bullet...in an autopistol, or any spring-assisted action...it doesn't tell the whole tale as far as felt recoil is concerned. Go and find a Smith 10MM revolver and shoot the ammo through it. Wear plugs and muffs to negate the sensory effect of the muzzle blast. I think you'll see that the 135/1180 load isn't quite as rambunctious as you think it is. If you have a good hand, you may even be able to tell the difference between it and the 180/940 load.
First, the calculation of bullet/recoil momentum is far too complex. The IDPA/USPSA's "Power factor" is no more than a measure of momentum...or how far the bullet will move a ballistic pendulum. Grain weight times velocity divided by 1,000 is the formula. Using this, the venerable .45 hardball load of 230/800 fps gives us a power factor of 184, and the same bullet at 750 fps just squeakes over the line with 172.
Using the same calculation, your 135/1180 churns up a power factor of 159. It doesn't make major, but it doesn't miss by much. The 180/940 does a little better at 169...barely missing major.
So, we have a little more momentum with the slower, heavier bullet...but not enough to feel any real difference on the other end of the gun. At least, not in my hand. Doing a side-by-side comparison of my 200 grain SWCs at 800 fps with my 230s at 800...I can tell a little difference if I'm really paying attention...but nothing like being reported in the .40 caliber 135/180 comparison.
So, there's obviously something else going on. That something is the slide's reciprocation and changing center of gravity. The speed of the recoil spring's compression, and the slide's impact with the frame.
Many people mistakenly believe that the recoil that the feel when firing an autopistol is the result of the actual action/reaction event between the bullet and the breechblock. It's not. What generates the felt recoil is the action/reaction event between the slide and the frame via the spring and the slide's suddent stop against the frame...and then we feel yet another one as the spring accelerates the slide back to battery. All that violent slam-bangin' around fools our mind into thinking" "Wow! This thing really kicks! It must be some kinda pow'rful!"
If you can arrange to shoot the same two rounds in a revolver, your brain won't be quite as impressed because it's all over with in one quick punch.
Then there's the matter of the mass of the powder charge. The 135/1180 uses a heavier charge...adding to the total mass of the ejectiva. That adds to the recoil momentum and energy by the weight of the powder charge in grains. There's also the matter of the pressures. Most often, the lightweight scrreamers are loaded to higher pressures. +P if you like. That accelerates the powder gasses...adding to the effect.
Incidentally, the heavier bullet's dwell time in the barrel has almost nothing to do with felt recoil in a pistol...and little more in a revolver. A rifle wth a 22-inch barrel...sure. The short recoil system of the 1911 and probably also the Glock, etal...only gets a recoil impetus during the first 1/10th inch or so of slide travel. At that point, the bullet is gone, and can't generate any more "push" through the force vector...and the slide continues on via the momentum conserved during that time. The few milliseconds' difference in dwell time between the two bullets is pretty much meaningless.
What is a real factor is the speed at which the slide compresses the spring. Newton's 1st law of inertia mandates that it takes more force to get an object moving than it takes to keep it moving, or even accelerate it to a higher velocity. We've seen that the greatest percentage of the bullet's final velocity occurs within the first half-inch of bullet travel. With really fast powders, it may even be less. Factoring in the bullet's inertial mass, it takes more force to accelerate the 135 grain bullet to some 970 fps...of the total of 1180...than it takes to accelerate the 180 to 730 fps, with the total being 940. The 135 grain bullet's velocity at a half-inch of travel is faster than the 180s is at the muzzle. Think about that.
Force forward equals force backward. This is Newton's 3rd law simplified. Whatever force drives the bullet is also visited on the slide. Simple physics determines that when a greater force is applied, an object of a given mass will accelerate faster than the same object with a lesser force applied. Witness that a peak pressure of 25,000 psi will produce higher velocities with a given bullet than will 20,000. Simple physics.
So...while the slide's momentum must be ewqual to that of the bullet...in an autopistol, or any spring-assisted action...it doesn't tell the whole tale as far as felt recoil is concerned. Go and find a Smith 10MM revolver and shoot the ammo through it. Wear plugs and muffs to negate the sensory effect of the muzzle blast. I think you'll see that the 135/1180 load isn't quite as rambunctious as you think it is. If you have a good hand, you may even be able to tell the difference between it and the 180/940 load.
Vern Humphrey
Member
One interesting experiment is to shoot the Colt Service Ace or Service Ace Conversion Kit. The floating chamber is actually noticeable, and you can feel if if you're paying attention. There is a double bump effect, first as the floating chamber hits the slide, then as the slide hits the frame.
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