115gr vs 124gr vs 147gr felt recoil

[IDescribe]

Right.  Given the same powder and power factor, 147 is softer than 124, which is softer than 115.  And gas volume is part of the equation.

As to personal preference, it comes down to how fast the gun is cycling, how fast the sights settle back down, and feel.  A 147 at PF130 feels sluggish.   For some people, the simple fact they FEEL like the gun is moving slower will make them slower.  Stupid brain!

Smitty, while you might find the 147's better than the 124's at the same power factor, you can also play around with different power factors.  While I will definitely say that at a PF of 130, 147 is softer than 124, I prefer the 124.  However, I am also a big fan of the 147 at a pf of 136/137.  Group sizes actually start tightening up for me at about PF 135 with 147gr bullets.  And for me, it doesn't feel sluggish anymore, but it's still softer with less muzzle climb than is the 124 at PF 130.  It's a nice combination.  Play around with it.  You might like what you find. 

[CZnewbe]

CZnewbe who sells 160 grain bullets?

Bayou Bullets.  BBI also makes them, but you may need to special order the thickness.  Also, let me say that I've never tried them in a CZ barrel.  My friends that shoot them, all shoot Glocks.

[KOBGT]

I've been shooting both BBI and Xtreme 135s, shoot nice and flat out of CZ SP01 Shadow.  They are definitely lighter than 124 and 115.  (But we are talking about 9mm Minor so recoil isn't a big deal anyway)

[kobus]

If you like the "idea" of the 124grn, but still want to go a wee tad heavier, then several bullet makers are offering 130grn and 135grn bullets.  These are generally listed under a caliber called 38 Super rather than 9mm.  They may also show these as .001" larger than traditional 9mm bullet diameters, but that is insignificant.

Look at Black Bullet Intl, Berry Mfg, Zero, Remington, etc.

the local manufacturer of bullets i use produce 115gr ; 124gr ; 135gr ; 147gr RN CMJ bullets; my favourite for practice is the 124gr but i also load a lot of the 135gr and enjoy shooting them in comp for the accuracy and softer felt-recoil.

[ACME Bullet Company]

As a large manufacturer of cast bullets I can add that the 124RN appears to be the most accurate of the 9mm.  We make the 9mm 115 RN, 124RN, 125RN, 147 FP and 38 160RN that we can size to .356 for those interested.  What we have seen in our testing results is that the 124RN is the most accurate due to the driving band length. 

These bullets have been tested in multiple firearms by 4-5 different third party testers with multiple load variations and has been the most consistent/accurate of the 9mm we produce.

The 9 115RN is by far the most popular bullet and standard for the 9mm.  It is also very accurate and pleasant to shoot.  Naturally is up to the shooter and his/her capabilities for accuracy.  I just thought I would add a manufacturers opinion as we test all of our bullets through numerous sources and also shoot ourselves.

As far as felt recoil-that is directly related to the specific load used.  www.acmebullet.com

ACME Bullet Company

[kneelingatlas]

I know that perceived recoil is more than just the physics.    But as a guy who used to teach physics to budding young naval officers, I can do the math.    Power factor is the same as momentum.   Momentum is force times time.

Momentum is actually mass times velocity, impulse is force times time, but I think energy as something to do with perceived recoil as well.

A 147gr bullet at 884fps is 130PF, a 115gr bullet at 1,130fps is also 130PF, but the 147gr has 255ft.lbf of muzzle energy while the 115gr has 326ft.lbf of muzzle energy.

This is not to say muzzle energy is the best predictor of felt recoil, but anyone who has fired a 115gr bullet at 180PF (626ft.lbf) next to a 230gr bullet at 180PF (313ft.lbf) can tell you energy is certainly not irrelevant 

This calculator takes a stab at it:  http://www.shooterscalculator.com/recoil-calculator.php

[Lemming]

Impulse is the change in momentum,  which is the quantity we are dealing with. It is calculated as force x time or, equivalently,  as mass times the change in velocity. Since the bullet starts at rest, this is exactly the same as mass x velocity.

[Smitty79]

I know that perceived recoil is more than just the physics.    But as a guy who used to teach physics to budding young naval officers, I can do the math.    Power factor is the same as momentum.   Momentum is force times time.

Momentum is actually mass times velocity, impulse is force times time, but I think energy as something to do with perceived recoil as well.

A 147gr bullet at 884fps is 130PF, a 115gr bullet at 1,130fps is also 130PF, but the 147gr has 255ft.lbf of muzzle energy while the 115gr has 326ft.lbf of muzzle energy.

This is not to say muzzle energy is the best predictor of felt recoil, but anyone who has fired a 115gr bullet at 180PF (626ft.lbf) next to a 230gr bullet at 180PF (313ft.lbf) can tell you energy is certainly not irrelevant 

This calculator takes a stab at it:  http://www.shooterscalculator.com/recoil-calculator.php

As my students used to say, I was just taking a couple extra steps without showing all of my work.   In an inertial reference frame, based on the shooter's left nostril, the force times time equals the impulse, the change in momentum.    Since the bullet starts with zero momentum, the momentum is force times time.

That said, since the smaller bullet spends less time in the barrel, the force has to be higher for it than it does for a heavier bullet.  In fact, there is even more force, as smaller bullets universally need more powder to get to power factor than heavier bullets and most of the combustion products go out the barrel too.   More force, probably higher peak force, more combustion products all add up to higher felt recoil. 

This isn't to say that some people aren't going to shoot better with a lighter bullet.  If you could properly analyze the gun, body, ammo system for a particular shooter, you may find that a certain load gets you back on target faster than others.    Lacking a good mathematical model for our system, most of us find our best load empirically.   I have measured the Bill Drill splits I get out of my CZ and I do better with 147 gn bullets than I do with lighter bullets.   I was surprised that it's almost 5 hundredths of a second.   This is probably meaningless, for a shooter at my level, for a field course.  In a fast classifier, it might count.

[Lemming]

Personally, I always use the shooter's RIGHT nostril as the frame of reference for this analysis,  but I'm prepared to let it go this time.

But only because it's you, Kneelingatlas

[1SOW]

Wanting to learn from those who have studied and understood the science/math involved.

To help make it clearer for those who don't know the math,  can you give us an example?   
GIVEN: the same powder,  same pistol and varying bullet weights  (115gr, 124gr, 147 gr) at the same power factor  (130 PF comes to mind),  can you show an illustration where recoil isn't directly related to powder load?   OR where greater powder amounts 'don't' equal greater recoil.?

[Smitty79]

From a physics standpoint, I would expect perceived recoil to be most affected by peak force, average force and gun weight.   Average force is most dependent on total energy.    Assuming the energy liberated is proportional to the powder weight, I think this is a good assumption for constant caliber and when the load isn't highly compressed, the force values should be about proportional to the powder weight.   Given that the burn thermodynamics may be radically different for a 15kpsi 45 ACP load vse a 30+ kpsi 9mm load, I don't think this holds as well.

All other things being equal, barrel length, gun weight, grip fit, powder type... , at constant power factor, I would expect felt recoil to be greater if you are using a bullet that needs more powder.   If the bullet fit and finish (Diameter and jacketed, lead, plated) is the same, I would the correlation to be stronger.   There are some second order effects that I am not accounting for.    But I don't think anyone, not even Angus, could detect them.

[1SOW]

Back to my yes or no question.

[Smitty79]

If you load all different weights of Bayou coated 9mm bullets and shoot them from the same gun at the same PF from the same gun, more powder should give more perceived recoil for the same powder.   The only place it might not hold true is for same weight bullets that have different seating depths and OALs.   That close, other things may take over.

That's as close to yes or no as I can get

[noylj]

Of course, the powder weight is so small compared to bullet weight...
It isn't like .223 Rem with 25gn of powder and a 50gn bullet.
It is not, from what I can tell, the recoil as the impulse. Most folks prefer a push to a jolt. I prefer the speed of the jolt as the gun cycles and returns to position "faster" for me. Others, obviously, feel and see it different.

[1SOW]

noylj,  I tend to agree lately---I didn't for a good while.
Using the givens above:
I suspect the ejecta (? the compressed gas escaping past the muzzle pushing the pistol back--equal and opposite)  is the source for delivering recoil.  The bullet's flight regardless of weight doesn't actually cause recoil changes.  It moves with the push from the powder.  If there is more or less powder used,  the recoil is also more or less.   I do agree that the acceleration rate of the powder burn is felt by the shooter.

Having shot and reloaded 9mm from 90 gr to 147 grain,  I've never seen an exception to the empirical evidence that recoil is determined by powder load.
Minor seating depth changes don't really matter if your staying approximately in the same power factor range.