Jump to content
SASS Wire Forum

Relationship of power factor and ft pds of energy.


Kirk James

Recommended Posts

Need help in understanding.  A 105 grain bullet at 600 fps has a power factor of 63 and produces 83.2 ft pounds of energy.  A 125 grain bullet at 504 fps has the same power factor of 63 and produces 70.49 ft pounds of energy.  What would be the difference in muzzle flip and felt recoil with the same weight firearm and the same powder?  By the way, my 2020 goal is to quit posting late at night!!!!!!!!

Link to comment
Share on other sites

FELT RECOIL is essentially a momentum force.    Power Factor (being a velocity times mass calculation) is an expression of momentum force.  

 

So, the felt recoil is the same for the two loads that each make 63 PF.    

 

Folks who talk about recoil ENERGY are being very sloppy with their Physics and confuse other folks.

 

So, where does projectile energy come in? 

 

The damage done to a target is largely an ENERGY effect.  Light bullets at high velocity deposit more energy since energy is a "mass times velocity squared" calculation.    Momentum (power factor) becomes much more important when the target is large and dangerous and deep bullet penetration is needed.  Thus, you get better results shooting large game with a .458 Winchester than a .220 Swift.  The effect on target varies between a need for energy and a need for momentum, depending upon target.

 

But the bottom line is, you surely can't be very affected by the recoil of a 63 PF handgun load, can you?.

 

Good luck, GJ

Link to comment
Share on other sites

I load 105gr and Trail Boss in 38SP specifically for the lowest revolver recoil for my wife and the highest case filling for me.

I use the standard recoil formulas in a huge spread sheet I wrote for load tracking and all things "gun."
Newton's 2nd Law applies here.
The heavier the projectile, and the faster it moves, the heavier the recoil.
The weight of the gun has a huge impact on the felt recoil.

The balancing act comes into play when using a low weight bullet and low velocity load.
SASS requires all-lead bullets, so matching the lead hardness (BHN) to the charge pressure becomes important.
My solution was having Ringer Bullets make a custom run of 105 grain,  soft-cast BHN=9, Hi-Tek coated LTCFP bullets.
 

Link to comment
Share on other sites

6 hours ago, bgavin said:

I load 105gr and Trail Boss in 38SP specifically for the lowest revolver recoil for my wife and the highest case filling for me.

I use the standard recoil formulas in a huge spread sheet I wrote for load tracking and all things "gun."
Newton's 2nd Law applies here.
The heavier the projectile, and the faster it moves, the heavier the recoil.
The weight of the gun has a huge impact on the felt recoil.

The balancing act comes into play when using a low weight bullet and low velocity load.
SASS requires all-lead bullets, so matching the lead hardness (BHN) to the charge pressure becomes important.
My solution was having Ringer Bullets make a custom run of 105 grain,  soft-cast BHN=9, Hi-Tek coated LTCFP bullets.
 

I load 105, 2.7 trail boss for 640 FPS in revolver, a 125, 2.7 trail boss for 740 in rifle, both have light recoil

Link to comment
Share on other sites

The thread wasn't to evaluate my loading data.  The example was given to me for a discussion pt.  Please stay on the discussion or find your own thread.  This is why people are going to other sources of media.   

Link to comment
Share on other sites

7 hours ago, John Boy said:

 

This is one of the common "confusing" sites I talked about earlier.   They calculate momentum.   They get the same recoil answers for the two loads that OP asked to compare.  

 

Yet, they label one of the answers as "recoil energy".    They should label it "recoil momentum."

 

Good luck, and conserve your momentum Isaac Newton.   

GJ

Link to comment
Share on other sites

Power factor is the ability to leap tall buildings with a single bound, Foot pounds of energy is how hard you kick somebodies @$$ back side

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.