Specifically, 9mm.

My question: 115 grain bullet at muzzle velocity of 1088 fps (302 ft. pounds of energy and Power Factor of 125) vs. a 147 grain bullet at muzzle velocity of 970 fps (307 ft. lbs energy and Power Factor of 143).

Which will give more felt recoil fired from the same handgun?

I've Googled the subject and spent time looking for a definitive answer and explanation but find a lot of conflicting information. I thought I'd try the collective wisdom that resides in this forum. :-)

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Illegitimi Non Carborundum

A 115 grs at 1088 is definetely very low recoil.

The 147 grs I tried were much slower than 970. So I can't really compare.

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Expect the unexpected

In my experience developing loads for my USPSA competition guns, lighter bullets at the same power factor as heavier bullets will always feel snappier and give more muzzle rise.

In OP's scenario, it would be difficult to say which would feel softer as the power factors are different. I would guess the 147's would feel softer due to smaller powder charge and lower velocity even though the PF is higher.

Math is your friend here and a ballistic calculator is your best friend.

Assume you have a 2.5 pound pistol and the powder charge weights are equal at about 6.0 grains:

115 gr at 1088 fps:

Recoil Impulse = .67 lb seconds
Recoil Velocity = 8.58 fps
Recoil Energy = 2.86 ft pounds

147 gr at 970 fps:

Recoil Impulse = .74 lb seconds
Recoil Velocity = 9.58 fps
Recoil Energy = 3.56 ft pounds

The 115 gr load is going to have less recoil impulse, less recoil velocity and less recoil energy.

ShootersCalculator.com | Recoil Calculator

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If you want apples to apples you need equal power factors and to get a power factor of 125 with the 147 gr bullet you need to slow it down to 850 fps.

147 gr at 850 fps:

Recoil Impulse = .67 lb seconds
Recoil Velocity = 8.57 fps
Recoil Energy = 2.85 ft pounds

That makes the recoil basically a dead heat.

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Power factor = (weight in grains) x (velocity) / 1000

Which is basically a proxy for momentum using simple to calculate units.

Heavier bullets have a big advantage when it comes to momentum as momentum is just mass times velocity. Lighter bullets tend to have an advantage when it comes it energy, as energy is mass times the square of the velocity, so velocity plays a much more important role.

Recoil of various loads can be a very subjective thing. Frankly, there isn't that much difference. There are a slew of other things that you should work on to try to improve your performance in matches instead of worrying about the recoil impulse.

BTW, you don't want loads that just barely make power factor. You need some extra in case of ammunition variation.

Wow! Great thanks to each of you who responded. Each reply is appreciated.

And, Special Thank you, Mr. BB57, for your in depth, enlightening response, replete with explanations and suggestions. Moreover, not only did you include all your calculations, you included the link to to allow me to crunch some numbers on my own. I genuinely appreciate that you took the time and effort for your reply.

Regards, Lance

PS I would really like to find some "store bought" 147 grain rated at 800 to 850 fps but so far have not found any. I'm going to put a bit more effort into searching. :-)

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Illegitimi Non Carborundum

There are so many changeable factors that enter into all this that it becomes pretty much a hair-splitting venture. Gun design and weight, grip angle, one's firmness of grip, uniformity of grip, and shooter technique and skill are just a few things to consider.

There's a place for numbers and textbook theory, but this isn't it. Shoot several loads with several bullets enough times at 25 yards and you'll answer your own question far better than someone else can.

Almost forgot. that 9mm load is really borderline on the power factor. it will only work if that is your lowest velocity in the SD.

Safe side in 9mm to make factor is around 1120 fps average for 115 grs.

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Expect the unexpected

1150 f/s & 115 gr gets you 132 pf. 1200 f/s gets you 140. 120 f/s gets you 13.8.

You're not going to find 147 gr store bought that slow.

You have recoil and power factor but you need to account for the burning speed of your powder also.

For example;
In the 12 Ga. shotgun with a 1 1/8 oz. payload doing 1200 fps
with a fast 18.2gr Red Dot powder and a slow burning 22.5gr Unique powder....
the pressures are 10,000 psi vs 7,400 psi................

One punches and the other pushes.

Revolver vs Pistol........... O/U vs Gas operated shotgun: A gas shotgun can reduce recoil by 40%.

Some say that MV is MV and they both come to the same recoil..
but I disagree.

ft/lbs energy vs ft/lbs of energy in bullet weight x vs weight Y being close to me is like apples to oranges.........

they are in the same ball park but.........

Vel and energys are nice but I like to take in penetration and expansion as part of my final selection for my SD ammo.

For target ammo, I don't like to beat up the weapon or me and go with light loads.......
so a PF of 125 or lighter is nice to have.

Usually the heavier bullet will produce less felt recoil.

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Freedom is never free!!
SWCA #3437

Felt recoil is very subjective .

My son has a 44 magnum Desert Eagle semi auto and a S&W 44 magnum revolver. Shooting the same factory ammo from both , side by side , we both felt the Desert Eagle recoiled more than the revolver .
In fact a few shots with the Desert Eagle and we were both done with it , the revolver was much more pleasant to shoot and we went on to finish the box of ammo with it.
In theory the heavier Desert Eagle semi-auto should have been the lesser recoiling ...but it kicked like a mule . My theory is that big slide slaming back then slamming forward may have added to the felt recoil ...but for whatever the reason the revolver was / seemed to recoil less and be a lot more pleasant to shoot .
Gary

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Certified Cajun
NRA Member

The Llama Model III-A is like a mini 1911, a locked breech .380. The FN Model 1910 is a very similar sized and weight pistol but is blowback operated. Using the same ammunition in each, the recoil impulse seems less in the Llama.

In practical terms, the FN's recoil seems snappier and has a bit more muzzle rise. I suspect the short recoil design of the Llama reduces the slide velocity and hence the flip.

For me, it is the muzzle flip that slows me down getting back on target. I have the same impression in shooting a High Power versus a 1911. I find it easier to get back on target with the .45. Regardless of what the theoretical numbers may say, the shot timer seems to bear me out.