Why does WSF recoil less than power pistol at the same velocity?

[mont1120]

I load both WSF and TG with my 147 MG and Blue bullet CO loads, and I cannot tell any difference between the two loads. When it comes to "perceived" recoil, I asked the same question a few years back in the 44/45 section, and the answer really lies in the combination of the physics surrounding gas, volume, weights, barrel length, and the relationships between all of them. Run a search in that section and there is an excellent article that really explains it.

 

In the end, what YOU feel is the best recoil reaction will be what you choose. Science sometimes takes a back seat to human perception.

[Smokecloud]

I started using WSF and WST in 40sw with really good results a few years ago. This was back when powder was non existent and I was trying to get my hands on anything that would work since I had burnt up all my TG.  I pretty much settled on WSF for Major PF loads in 40 and WST for the light loaded stuff.  I then started using both in 9mm.  One thing that I found was that the WSF had a pretty wild ES when loaded light.  As long as I pushed it hard, it was fine.  WST was more consistent on the light side, but showed pressure signs quicker when I started running it on the higher end. Velocity consistency is a variable that has not been discussed much on this topic.  That being said, I have yet to go back to TG because I like the way that the WSF feels in my 40.  

[IDescribe]

15 hours ago, Smokecloud said:

One thing that I found was that the WSF had a pretty wild ES when loaded light.  As long as I pushed it hard, it was fine. 

 

Velocity consistency is a variable that has not been discussed much on this topic.  

 

What you've noticed is accurate, and it's one of the things that makes WSF less than ideal for 9mm minor.  And it's been missed by a lot of people commenting in this thread. 

 

When powder ignites, it blows out the case walls against the chamber walls and creates a pressure seal.  Without that seal, expanding gasses would blow burning and unburnt powder out between the case and chamber walls and back into the gun instead of driving the bullet down the barrel as intended. 

And in fact if a powder charge is too light for its burn rate and bullet at the OAL employed, you get a late pressure seal, in which case a little powder and gas does exactly that: it escapes around the case walls and gets wasted.  When that happens, how much gas and powder gets lost is highly variable, and thus ES and SD numbers get high.  That's why light loads with WSF have high ES and are dirty - - a late pressure seal and consequent lost gas and powder. WSF is just a tad too slow a powder for 9mm minor, unless you want to run a PF in the mid-high 130s or higher, where it starts to clean up nicely, though recoil will be a bit elevated relative the faster powders more typical of 9mm minor loads. 

 

Always, always, always - - when you're loading, people should set design goals based on application.   

 

1. What is the application? 

2. What are the desirable characteristics for this application? 

3. What is the best caliber choice to best meet the need for these charactersistics? 

4. What is the best bullet choice at what velocity? 

5. What powder best gets that bullet to that velocity while meeting other design goals? 

 

When people say they like powder XYZ for 9mm, they're missing the point of reloading.  9mm isn't an application, so they skipped the first two steps. A loader should not be choosing the same powder for 9mm minor as they would for an SD load.  Design goals are too different.  Even with something like SD vs NRA 50-yard Bullseye, where a 115gr XTP at 1200 feet/sec is an excellent choice in both cases, you wouldn't necessarily choose the same powder, as Power Pistol might be THE best powder for 50 yard accuracy with 9mm, but as the bright flash and loud report of Power Pistol is not something you want in your bedroom in the middle of the night to blind and deafen you, it fails to meet the needs for a Self Defense powder. Compare SD to minor PF action pistol shooting, and conflicts are all the greater. 

 

To address the original question of the thread.  WSF recoils less than Power Pistol with the same bullet at the same velocity in the same pistol because there is less gas mass.  Period.  That gas mass is part of the recoil impulse. 

 

And WSF recoils more than faster burn rate powders when all else equal because it employs higher gas mass. Period.  I've loaded the same bullet to the same velocity with different powders of significantly different burn rates and tested them head to head in the same pistol, specifically looking to compare recoil.  The powder that takes more powder to reach the same velocity has stronger recoil.  Most of your recoil impulse is a function of mass and velocity.  A 124gr bullet at 1070 will have a very similar feeling recoil impulse, regardless of powder choice, but the one that uses more powder to get there will have a slightly stronger version of that impulse. If someone thinks WSF is softer than something like N320, they simply haven't done a true apples to apples test. 

 

Regarding some other odd claims made in the thread, people can absolutely prefer the recoil impulse they get from a slower powder, requiring more powder to reach the same velocity, but it's not softer.  It's simply not. And a meticulous test of the matter, apples to apples, all else equal, will demonstrate that to anyone without significant nerve damage or psychosis.

 

[4n2t0]

I'm pretty sure most people understand that on paper all that looks great but in the hand one cannot perceive the minute recoil difference between WSF and TG when loaded at 130 PF. 

 

 

P.S. WSF stayed pretty consistent for me on the low end.

 

FIREARM    BRASS    PRIMER    POWDER    LOAD    PROJECTILE    OAL    AVG    ES    SD    PF    TEMP
Ruger SR9/9E    Mixed    Fiocchi    WSF    3.9gr    CamPro 147gr RNFP    1.135    870    27  10    127    27° C
Ruger SR9/9E    Mixed    Fiocchi    WSF    4.1gr    CamPro 147gr RNFP    1.135    902    25    8    132    27° C
Ruger SR9/9E    Mixed    Fiocchi    WSF    4.3gr    CamPro 147gr RNFP    1.135    943    26    8    138    27° C

 

P.P.S. Here's my TG data which was used for the calculations above.

 

FIREARM    BRASS    PRIMER    POWDER    LOAD    PROJECTILE    OAL    AVG    ES    SD    PF    TEMP
Ruger SR9/9E    Mixed    Fiocchi    Titegroup    3.2gr    CamPro 147gr RNFP    1.135    834    30    10    122    27° C
Ruger SR9/9E    Mixed    Fiocchi    Titegroup    3.4gr    CamPro 147gr RNFP    1.135    865    18    5    127    27° C
Ruger SR9/9E    Mixed    Fiocchi    Titegroup    3.6gr    CamPro 147gr RNFP    1.135    900    8    2    132    23° C

 

Edited May 26, 2018 by 4n2t0

[IDescribe]

In will add that in my own testing of WSF, with minor PF loads, I have found it to start behaving consistly at lower PF numbers with coated lead bullets than with jacketed, and the heavier the bullet, and the larger the diameter, the sooner it starts behaving.  In my testing, it looked like minor PF with heavier coated lead might be acceptable, but still not ideal. 

 

Regarding SD, I'm accustomed to getting SD numbers in the 5-6 range, and of course a 7 and 8 here and there, and occasionally a 4, and ES typically under 20 with the powders I use for 9 minor.  That said, how precisely the groups print on paper is vastly more important than ES and SD, and in that regard, WSF does quite nicely. 

 

Regarding your SD and ES numbers above, I have found shiny copper plated bullets to produce higher ES and SD than lead or coated lead when using a chrono with light sensors, so your numbers are quite good to my eye for plated.  

 

 

[wgj3]

I still believe that there is more physics to this conversation.

Faster-burning powder accelerates bullet faster. Acceleration is different from simple velocity. The fastest powders accelerate the projectile to the final velocity quicker because they burn fastest.

Slower powders may ultimately achieve the same velocity at the chronograph, but depending on just how slowly they burn, they may still be accelerating the projectile more all the way down the barrel to the muzzle.

The difference in "perceived" recoil is comprised of more than just different powder/gas masses for different powders.

[IHAVEGAS]

1 hour ago, wgj3 said:

I still believe that there is more physics to this conversation.

Faster-burning powder accelerates bullet faster. Acceleration is different from simple velocity. The fastest powders accelerate the projectile to the final velocity quicker because they burn fastest.

Slower powders may ultimately achieve the same velocity at the chronograph, but depending on just how slowly they burn, they may still be accelerating the projectile more all the way down the barrel to the muzzle.

The difference in "perceived" recoil is comprised of more than just different powder/gas masses for different powders.

 

Maybe add to that the fact that the bullet is fighting its way through the rifling and pushing the barrel in a direction opposite the recoil direction. 

[PhillySoldier]

Im glad I came across this thread. I just finished journaling elsewhere this morning about some 9mm testing I was doing. For the last month Ive been ransom rest testing some different things using Power Pistol. I found it extremely accurate but really didnt like the kick it seems to have with it.  I regularly also shoot 45 and 50ae, so its not like increase recoil normally bothers me. And this may be all in my head but I think its taking a toll on my recoil spring already. Anyway I'd like to find a powder as accurate with less recoil. I was thinking about trying Titegroup or WSF next but open to try whatever most recommended?

[4n2t0]

Titegroup's very accurate in 9mm (and it's cheap!) but there are some negatives (snappy?, dirty on the low end, smokey w/ lead, makes the gun hot etc.). For 9mm you'll get all the usual recommendations: Titegroup, N320, Prima V, E3, Clays, WST (another of my favourites), American Select, HP-38/W231, Unique, WSF and more. Some of these powders are more versatile than others and if you're loading for multiple calibres that may factor into your decision making process.

Edited July 5, 2018 by 4n2t0