Power Factor for Matching Practice & Carry Ammo

[socal m1 shooter]

I'm not a competitor, so my understanding of power factor is limited and not based on competition experience.

But I was looking to put away some ammunition for practice before the law changes, and I wanted to get something relatively inexpensive that would allow me to practice with a carry pistol and closely approximate the tactile experience of shooting my carry ammunition, which costs at least five times as much.

So what I was wondering is, if I buy ammunition for practice that has a power factor close to my carry ammunition, is that a reasonable guarantee that the experience of shooting that ammunition will reasonably approximate the experience of shooting my carry ammo, which is loaded on the hotter end, but with an uncommon bullet weight?

[DRM6000]

If you state what kind of defensive ammo you shoot, maybe somebody will know what is similar.

Compare the bullet weight and velocity of what you use to what you're shopping for. I use Federal HST 180gr .40S&W and the the velocity is listed as 980 fps. If I want something similar, I'd start looking at Federal FMJ ammo.

[socal m1 shooter]

I have some Corbon 165 gr .40 S&W which is nominally 1125 fps. I saw some .40 on sale which claims 180 gr at a nominal 1017 fps. In terms of the metric version of the power factor, the Corbon is about 1.3% higher, but I wonder if that is noticeable.

Looking to get some in a case quantity before July 1st.

[DRM6000]

Here is a 165gr .40S&W that has a velocity of 1150fps.

https://www.targetsportsusa.com/remington-umc-40-sw-ammo-165-grain-full-metal-jacket-l40sw4-p-1344.aspx

I wouldn't know if the feel of the recoil impulse is similar. I think if one's marksmanship fundamentals are good, it shouldn't matter much.

[anonymouscuban]

Power Factor = (bullet weight x FPS) / 1000



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[anonymouscuban]

I have some Corbon 165 gr .40 S&W which is nominally 1125 fps. I saw some .40 on sale which claims 180 gr at a nominal 1017 fps. In terms of the metric version of the power factor, the Corbon is about 1.3% higher, but I wonder if that is noticeable.

Looking to get some in a case quantity before July 1st.

The 2 rounds you list have a similar PF. Recoil should be the same. I reload and compete but haven't been doing either long enough to be an export on this topic. I can say that through my limited experience, at least from a perceived recoil and how the gun will react, both of these round should be very similar.

Accuracy however, may not be. That will be dependent more on the particular gun your shooting.

But no expert here so I may be wrong.

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[Colt]

I know very little, but I believe Speer tries to make Lawman FMJ very similar to Gold Dot HP, so one can practice w/Lawman and closely replicate the Gold Dot performance.

I wonder if other manufacturers do similar.

[socal m1 shooter]

Here is a 165gr .40S&W that has a velocity of 1150fps.

https://www.targetsportsusa.com/remington-umc-40-sw-ammo-165-grain-full-metal-jacket-l40sw4-p-1344.aspx

I wouldn't know if the feel of the recoil impulse is similar. I think if one's marksmanship fundamentals are good, it shouldn't matter much.

Appreciate that, but I was considering some of this stuff, which is a bit cheaper.

[sigstroker]

Can't you just buy a box of 180's at the store and try it? There's nothing unusual about the Geco velocity so ordinary 180''s should be similar.

[broadside]

Using power factor is not sufficient.

My 147gr at 890 FPS are like shooting cotton candy but 124gr at 1050-1100 FPS are snappy buggers, but they are within a few points on PF scale.

I can remedy it some by swapping recoil springs but the gun is still behaving differently. You should pick ammo that is close in weight and velocity, but even then the powder burn rate could make them feel different.

[ar15barrels]

I have some Corbon 165 gr .40 S&W which is nominally 1125 fps. I saw some .40 on sale which claims 180 gr at a nominal 1017 fps. In terms of the metric version of the power factor, the Corbon is about 1.3% higher, but I wonder if that is noticeable.

Looking to get some in a case quantity before July 1st.

Power factor does not account for energy.
If you want the recoil to be the same, you need to shoot the same bullet weight at the same velocity.
This is because energy is the square of the velocity times the bullet weight.
So even though the power factor is within 1.3%, the energy of those two loads is 464ft-lbs vs 413ft-lbs.
That's 12% difference.
Here is a simple energy calculator: http://www.ballistics101.com/muzzle_energy_calc.php

Shooting a different bullet weight at a different velocity changes how the gun recoils.

[ar15barrels]

The 2 rounds you list have a similar PF. Recoil should be the same. I reload and compete but haven't been doing either long enough to be an export on this topic. I can say that through my limited experience, at least from a perceived recoil and how the gun will react, both of these round should be very similar.

But no expert here so I may be wrong.

You are wrong.
Power factor is a calculation used in shooting games.
Many people "game" the system by shooting the absolute heaviest bullet they can at the lowest velocity.
That's how you get the least recoil at the minimum power factor of your class.

Energy stored in the bullet and powder is what creates the recoil impulse so you need to accurately calculate energy to have a baseling to compare.

Power factor is NOT an energy calculation.

[ar15barrels]

My 147gr at 890 FPS are like shooting cotton candy but 124gr at 1050-1100 FPS are snappy buggers, but they are within a few points on PF scale.

147@890fps is 130.8 PF and 259 ft-lbs of energy.
124@1055fps is 130.8 PF and 306 ft-lbs of energy.

[broadside]

147@890fps is 130.8 PF and 259 ft-lbs of energy.

124@1055fps is 130.8 PF and 306 ft-lbs of energy.

They still don't shoot the same. different acceleration profiles means different type of recoil behavior.

[anonymouscuban]

You are wrong.

Power factor is a calculation used in shooting games.

Many people "game" the system by shooting the absolute heaviest bullet they can at the lowest velocity.

That's how you get the least recoil at the minimum power factor of your class.



Energy stored in the bullet and powder is what creates the recoil impulse so you need to accurately calculate energy to have a baseling to compare.



Power factor is NOT an energy calculation.

Thanks for the information. I said I may be wrong. I should have said I'm probably wrong. LoL

I think maybe he OP should consider reloading.

It's why I started. Once I started competing, the cost of ammo at the rate I was burning through in practice was limiting me. So I bought a reload setup so I can shoot more.

Not sure though if the volume the op wants to shoot justifies reloading. Something to consider though.

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