9 mm recoil: 147 gr or 124 or115?

[randyflycaster]

Yesterday I shot a box of 115 grain, and I was surprised at the recoil. I don't know the velocity of the ammo. I did some research, and it seems that, as a general rule, the heavier grain the less the recoil. Is this true? And what grain do competitive shooters use?

Thanks,
Randy

[JRV]

It’s less about actual recoil and more about feel/slide velocity (perceived recoil). Factory ammo is a wash, purpose loaded match ammo (commercial or hand-loads) is different. By that I mean, there’s a good bit of 124 grain 9mm on the market that’s loaded much hotter than it needs to be in order to mimic NATO spec. And, 147 grain factory ammo tends to hit 950-1,000 FPS, duplicating standard pressure defensive loads, and not necessarily providing the perceived recoil benefits attainable with heavier bullets.

Heavier bullets leave less case capacity for powder and need a lower overall velocity to make power factor. A subsonic 147 grain load, purpose loaded for match shooting, only needs to go about 870 FPS to ensure it will make 125 PF in nearly all atmospheric conditions, whereas a 115 grain load needs to go about 1,100 FPS to hit the same PF.

That’s extra slide velocity and report in return, which contributes to a “snappier” feel than a match 147 grain load. Heavier bullets tend to have more of a “pushy” recoil feel.

You have to test it out for yourself and not presume one particular load will make shooting easier, because the way your gun cycles (slide mass, spring rates) and your own biomechanics dictate how your sights return to point-of-aim. I usually warm up and run Bill Drills when I am choosing between (or trying to get acclimated to) different ammo. Regardless of perceived recoil, your natural tempo and post-shot recovery might provide best results with a particular bullet weight.

[Artemas2]

SHhhh don't let the secret out of the bag:cool:

Factory loads can be an exception depending on load, but if one is loading for a specific power factor (weight X velocity/1000) a heavy bullet requires less powder which makes less gas and has less speed leaving the barrel. So less impact on the shooter.

Or something like that.

Most USPSA shooters I know use either 124(125 if coated) or 147. Both can work well depending or what the gun and shooter prefers. Heavier bullets are more reliable when is comes to knocking down steel poppers, particularly big heavy poppers at distance.

[randyflycaster]

Great info.

I should say I don't reload. I've been looking for 147 gr to try it out, but with this ammo shortage I can't find it, and if I buy online I'll get hit with a heavy shipping charge.

Besides, I was just curious.

Randy

[ST911]

Yesterday I shot a box of 115 grain, and I was surprised at the recoil. I don't know the velocity of the ammo. I did some research, and it seems that, as a general rule, the heavier grain the less the recoil. Is this true? And what grain do competitive shooters use? Thanks, Randy

Entirely load dependent, in combination with the gun.

And lot-to-lot variations in the same sku can be significant in current conditions.

[MistWolf]

...it seems that, as a general rule, the heavier grain the less the recoil. Is this true?...

If that were true, everybody would go back to shooting 230 gr 45 ACP.

There are two types of recoil that a shooter needs to be aware of. Free Recoil and Felt Recoil.

Free Recoil- This is the recoil of the firearm when fired. There are three factors when calculating free recoil:
1) Mass of ejecta. This is the mass of the bullet and powder
2) Mass of the firearm
3) Ejecta velocity. There are two different velocities
A) Velocity of the bullet
B) Velocity of the expanding powder after the bullet uncorks the muzzle. Velocity of expanding gas from smokeless powder is a constant. I forget what it is, but if I recall, it's 5,700 fps.

Free Recoil is increased when-
- Ejecta mass in increased (bullet and/or powder mass)
- Bullet velocity is increased
- Firearm mass is decreased

Free Recoil is reduced when-
- Ejecta mass is decreased
- Bullet velocity is decreased (Velocity of expanding gas is a constant. It does not increase or decrease.)
- Firearm mass is increased.

Getting back to the question above, is it true (free) recoil is reduced with a heavier bullet? The answer is, to reduce free recoil with a bullet of increased weight, the velocity must also be decreased. The velocity must be decreased enough to more than offset the increase in free recoil from using a heavier bullet.

If a heavier bullet is launched at the same velocity as a lighter bullet, of course, there's an increase in free recoil. A 147 gr bullet at 1000fps is going to kick harder than a 115 bullet at 1000fps.

The other type of recoil a shooter is concerned with is Felt Recoil. Where free recoil is subjective and its energy can be calculated easily, Felt Recoil is objective and if it could be calculated, it would require more sophisticated calculations. Felt recoil is changed by fit, acceleration and deceleration of reciprocating mass, everything that affects free recoil, unsprung mass to sprung mass, brakes, type of buttpad, how many layers of clothing worn by shooter and even personal preference and mindset. It gets complicated fast.

One factor as discussed earlier in this thread, is acceleration rate of the bullet. Some rounds feel softer because the payload is accelerated as a slower rate even though they may actually generate more recoil. What this means is, softer recoil isn 't less or more recoil, it's just softer and can be more comfortable. When people say rounds with heavier bullets have less recoil, what they probably mean is, the load feels softer.

[revchuck38]

Yesterday I shot a box of 115 grain, and I was surprised at the recoil. I don't know the velocity of the ammo. I did some research, and it seems that, as a general rule, the heavier grain the less the recoil. Is this true? And what grain do competitive shooters use?

Thanks,
Randy

It's true that, at a given power factor (bullet weight x velocity/1000), heavier bullet ammo will have less perceived recoil, all other things being equal. It's just that all other things aren't equal. :)

Different brands of 115-grain ammo are loaded to different velocity levels, and those levels are ranges rather than specific numbers. European stuff tends to be hotter than American stuff. Manufacturers go with whatever powder they can get a good deal on that delivers velocities in the desired range at safe pressures. Slower powders require heavier charges to get to a given range and also produce more unburnt powder which influences recoil due to increased ejecta (see above post).

Now that the ammo situation is stabilizing, I'd try different brands and see which you like and stick with that. For most of us, the brand we like is whatever's on sale, and we live with the minor differences in recoil.

[randyflycaster]

Then if I am buying factory ammo how do I know which ammo has less recoil?
Thanks,
Randy

[Squib308]

Momentum is conserved
Kinetic energy is not conserved

Assuming blast and sound are not considered, physical “Recoil” is related to momentum, which is why very fast lighter projectiles will generate far less “recoil”. In terms of handguns it gets more complicated due to physical characteristics of the pistol-operator interface, slide mass, recoil springs, hammer spring or other factors than can either temporize or “absorb” the forces. Time is also a huge factor…the same force over a shorter time period will be perceived as much stronger although by Newton’s 3rd law it’s the same.

[MistWolf]

Then if I am buying factory ammo how do I know which ammo has less recoil?
Thanks,
Randy

One way is with the Recoil Calculator- https://shooterscalculator.com/recoil-calculator.php

Using load data from the Hornady Handbook of Cartridge Reloading (8th Edition) I used the above calculator to calculate the recoil of 147 & 115 gr loads fired from a Glock 17. According to the Glock website, a Glock 17 weighs 2.02 lbs with a full mag and 1.55 with an empty mag.

Choosing the slowest 115 load (1000 fps) with the lightest powder charge, Free Recoil from a fully loaded Glock (2.02 lbs) is 3.7 ft/lbs. With the heaviest powder charge (same velocity) Free Recoil is 3.55 ft/lbs. Free recoil from a Glock with an empty mag (1.55 lbs) is 2.84 and 3.53 ft/lbs respectively.

At max velocity (1250 fps) the lightest charge from a fully loaded Glock generates 4.93 ft/lbs of free recoil. Heaviest charge is 4.99 ft/lbs. From an empty mag (1.55 lbs) it's 6.43 & 6.5 ft/lbs respectively.

A 147 gr bullet at 750 fps from a fully loaded Glock 17, lightest powder charge is 2.56 ft/lbs, heaviest is 2.87. From an empty Glock, it's 3.34 and 2.87. Same from an empty Glock is 3.34 and 3.74.

147 gr bullet at 900 fps is 3.67 & 4.14 and 4.78 & 3.34.

At 1000 fps second, we have 4.67 & 5.12 and 6.09 and 6.67.

You can see that your handgun recoils on the first shot from a full mag than it does on the last shot when the mag is empty.

When using the above calculator, figure an average powder charge of 5 grains for 115 & 124 gr bullets and 4 gr for 147 gr bullets.

[MistWolf]

Momentum is conserved
Kinetic energy is not conserved

Assuming blast and sound are not considered, physical “Recoil” is related to momentum, which is why very fast lighter projectiles will generate far less “recoil”. In terms of handguns it gets more complicated due to physical characteristics of the pistol-operator interface, slide mass, recoil springs, hammer spring or other factors than can either temporize or “absorb” the forces. Time is also a huge factor…the same force over a shorter time period will be perceived as much stronger although by Newton’s 3rd law it’s the same.

In this post, you're talking about free recoil and felt (perceived recoil), mixing the two in a confusing manner. Free recoil is quantifiable. Though related, they aren't the same. Felt recoil, not so much. Felt recoil is very much a matter of opinion of the shooter.

[JSGlock34]

There's a reason why Federal built their popular 9mm Syntech Action Pistol (https://www.federalpremium.com/handgun/syntech/syntech-action-pistol/11-AE9SJAP1.html)loading around a 150 grain bullet.

https://www.federalpremium.com/dw/image/v2/BDBJ_PRD/on/demandware.static/-/Sites-vista-master-catalog/default/dw4753e943/images/large/FP_AE9SJAP1_9mmLugerTSJSyntechActionPistol_Combo_R .jpg?sw=800&sh=800&sm=fit

This round is popular in USPSA; besides competition I've also used it when instructing recoil sensitive shooters.

Note that there are a number of Syntech loadings now; the Action Pistol load is particularly geared for USPSA shooters looking to satisfy Power Factor requirements. Some Syntech loads are designed to matched defensive ammunition, and obviously these will not have the same recoil characteristics.

[Jim Watson]

To the OP: If the box label or catalog listing shows bullet weight and velocity, multiply them to get Power Factor. Lower Power Factor, less recoil as a general thing.

You have to get deeper into the physics to see what is going on when two loads of the same Power Factor or computed recoil have different "felt recoil." For which I am not much qualified, but I know there is stuff going on inside the gun. I think one contributor is bullet acceleration. A heavy bullet off to a slow start and getting up to a lower muzzle velocity appears likely to disturb the gun less. There may even be a factor for change in acceleration as powder burns up and friction increases, sometimes called "surge".

And while the mathematics ignore muzzle blast and flash, the human nervous system does not.
I saw that last week. I had sluggish function from my 124 gr Minor power factor reloads in one gun, so I splurged on some 115 gr econoball which worked better. The loud bang, supersonic crack, and bright flash were a jar.

[randyflycaster]

Folks,

Thanks so, so much for all your great answers. Very helpful. I've learned a lot.

Randy

[1911Nut]

In the context of 9mm . . . . . what is this "recoil" of which you speak?

Sorry, I couldn't help myself.

[JMS]

I don't think that that's completely out of line; I think most of the folks who talk of 9mm perceived recoil overfocus on it. The idea that one should attempt to cultivate a certain level of insensitivity to recoil has value. "Climate's what you expect, weather's what you GET." Perceived recoil can wander between lots, altitude, temperature, along with all the other nitnoid crap *ahem* I mean data that folks track.

...and I say that having deliberately chosen to zero everything I have to 147gr HST (147gr ball to practice/train/compete) across the board due *at least in part* to 147gr typically (not universally) having less perceived recoil...plus the longer projo having better engagement with the rifling, which typically provides for better accuracy in my guns.

...and because, in the (still ongoing, to me, with more to come now that we're seeing imports banned) drought, I snapped up soooo much because-I-could-get-it good 124gr because having reasonable quality ammo to shoot trumps what it's perceived recoil may be. I just eat the POI shift, which is typically >1"@25yd for mine. Insignificant.

Hells, when I was shooting 124gr exclusively, I'd practice with hotter ammo...as stated, non-US brands like Magtech and S&B tend to use the NATO recipe...and shoot comparatively cheesy-poof-recoil US stuff for scored events.

We could really start baking noodles, and bring up comps.... ;)

[Squib308]

In this post, you're talking about free recoil and felt (perceived recoil), mixing the two in a confusing manner. Free recoil is quantifiable. Though related, they aren't the same. Felt recoil, not so much. Felt recoil is very much a matter of opinion of the shooter.

What’s the difference between momentum (m x v) and “free recoil” ?

[peterb]

And while the mathematics ignore muzzle blast and flash, the human nervous system does not.
I saw that last week. I had sluggish function from my 124 gr Minor power factor reloads in one gun, so I splurged on some 115 gr econoball which worked better. The loud bang, supersonic crack, and bright flash were a jar.

Which is why I always have new shooters double up on hearing protection if possible. Decreasing noise can decrease perceived recoil.

[MistWolf]

What’s the difference between momentum (m x v) and “free recoil” ?
M x V leaves out a lot of important information, such as mass of firearm, mass of powder charge and velocity of gases exiting the muzzle.

Launching a bullet launching a 147gr bullet @ 1100 from a ten pound firearm is gonna have less free recoil than it would from a 5 pound firearm.