FIE Mod TZ75 Custom 90

[Rod Slinger]

jwc007....Please explain how retarding the unlocking time of an auto pistol would increase the recoil.   Thanks R S

[Walt-Sherrill]

Now that you mention it, I'd like to see that explanation, too.
<grin>

[jwc007]

Please remember that Browning/SigPetter locking system was designed to partially absorb recoil, otherwise you could get away with just a Blowback Action and heavy springs. (Hi-Point Pistols are Blowback as are smaller calibered pistols.)

The longer the barrel and slide stay locked together/motionless, and the longer the duration of the barrel/slide motion to unlock, the more energy is transferred to the frame and thus the hand/arm of the shooter. (If the motion of the action is retarded too much, more energy will go to the shooter.)

Conversely, if the Barrrel and Slide move and unlock too soon, the Slide will impact the Frame Slide Stop shelf with more impact than is desired, also transferring more energy than is desired, to the frame, and then the shooter.

Somewhere in between these two conditions is a balanced action that allows optimum absorption of energy by the action, lessening recoil as much as possible, yet providing positive action.  It will never be 100% efficient absorbing all recoil energy, but it can be optimized!

In my experience, I have found there was more recoil with an 18 lb recoil spring installed in my .45 Witness, than with the 16 lb recoil spring.  Ammunition was standard WWB 230 grn FMJ.

In another 9mm Pistol (Taurus PT92) which had a worn Factory standard 13 lb recoil spring and a worn, but yet functional Main/Hammer Spring, I found that going to a 15 lb recoil spring significantly reduced recoil, yet did not harm cycling reliability.  I believe that going to a heavier than 15 lb spring in that pistol (and I did try an 18 lb) would be overboard. (It did not feel right) Ejection was weak with CCI Blazer and my Match loads.

I did have a conversation with a Rep at Wolff, and he believed that most Standard sized 9mm Pistols tend to work better with Recoil Springs in the 15 to 16 lb range.  Such Pistols with issue 13 lb springs tend to be "undersprung".  (S&W, Browning HP, CZ, and Beretta/Taurus)

I have noted that some owners of original CZ's, here, have opted for Wolff 16 lb recoil springs in their CZ75B's.

As I have previously noted, Tanfoglio Recoil Springs, while officially rated at 14 lb.s behave more like 15 lb.ers and that may have more to do with the way that spring is made.

If one is unsure of what to install, I generally recommend staying within 2 lb.s of Factory Standard, unless you are contending with a 10mm or .45 Super, then all bets are off!  A Wolff Calibration Pack is sometimes in order.

Also, if the Main/Hammer Spring is worn or decreased in normal strength, a heavier Recoil Spring is often installed to compensate, as the Hammer/Main Spring and Recoil Spring are additive.

Shadetree/Amatuer Gunsmiths often clip coils off of main/hammer springs to lighten DA Trigger pulls, only to find recoil increased, and down the road when the hammer spring wore, not enough energy to set off primers.

[Rod Slinger]

jwc007.....You nailed it!!!   This is one of the best explanation of the relationship between recoil spring to hammer spring I have seen.  I hope you tag this and keep it in play.  

How I test my guns to see if they are over sprung is to shoot weak hand only.  If the gun cycles four are five Mags with out a failure to feed then I am happy with the spring weight.  What say you??   R S

[Walt-Sherrill]

Energy is being transferred long before the slide is fully locked.  Transfer begins as soon as the slide starts to move.  

(The spring must have a base against which to press, and that base must resist and take force...)

I think different weight springs change the "experience" of the recoil, the IMPULSE, spread it out so that it feels different.

I'd argue that too light a spring means that less is stored (so that less can be attenuated or have the impulsed "changed" or slowed), therefore more energy is passed to the arm and frame.  

While you may be correct, from a theoretical perspective, I don't see how a heavier recoil spring can make for heavier felt recoil.  

Where is a physicist when you need him (or her)?

[Rod Slinger]

Walt....  Think about this if you had two rifles and both are identical except one was a bolt action and one was an Simi-automatic, most would agree that the bolt action will kick more.  In fact they may have nearly the same recoil but the auto spreads its recoil over a longer interval thus being perceived more as a push rather than a kick.   This must also apply to handguns.  

In a perfect would an auto pistol would recoil the slide rearward to the point to where it would just touch the frame.  Add more spring poundage and it will short cycle.  Less poundage and the slide slamming into the frame becomes part of the recoil.  Most slides weigh more than a 115 gr. 9 mm.  

So I find no disagreement with you or Mr. 007.  

In fact I believes this goes to the hart of understanding the care and feeding of the auto pistol.   Thanks  R S

[Walt-Sherrill]

Think about this if you had two rifles and both are identical except one was a bolt action and one was an Simi-automatic, most would agree that the bolt action will kick more.

But, part of the force of the recoil is being used to operate the weapon.  Its being put to work and dissapated in that manner.  Doesn't the semi-auto rifle also output less force, too?  

In either case, that doesn't explain why a heavier recoil spring allows MORE FELT RECOIL than a light one.  While a  part of the force is being dissapated in working the spring and being turned into heat, its only a very, very small, insignificant, part... and that should REDUCE felt recoil, not increase it.  

In a perfect wo[r]ld an auto pistol would recoil the slide rearward to the point to where it would just touch the frame. Add more spring poundage and it will short cycle. Less poundage and the slide slamming into the frame becomes part of the recoil. Most slides weigh more than a 115 gr. 9 mm.

So I find no disagreement with you or Mr. 007.

Short-cycling doesn't address the issue of more or less recoil -- it addresses whether the gun functions properly and gets itself ready for the next shot.  Let's ignore short-cycling.

The gun moves rearward with the same force when the cartridge is fired (equal but opposite reaction) regardless of the spring used.  What happens next is what's different.

What none of this addresses is where the recoil goes and how it is experienced.  

How do recoil reducers like the SPRINGCO work?  They change the impulse, as I understand it -- spreading it out over a longer period of time.  The recoil becomes a push rather than a quick jab.  (Some of these devices have multiple springs, taking up different amounts of recoil at different times. Some have small amount of dense mercury  to give more mass and increase inertia.)  

I would argue that the recoil all goes into the gun and doesn't just magically disappear.  You guys seem to be saying it just goes away.  It can't.   The spring stores part of it, but must do something with it -- and when it does, that's "work" that you feel.  

The spring stores part of the force sends some of foward to cycle the slide when the slide hits the receiver stop.  Part is felt going back, and part is felt going forward, but the going-forward part is less obvious.   But the stored amount is different, depending on the power of the spring used.

If its a light recoil spring, part of the full force is stored and a larger part isn't -- and the part that isn't stored is felt immediately, in a heavier hit against the hand.  With a heavier recoil spring, more is stored, and arguably felt on the slide/s return (but it's not generally noticed.)  

That's why some of us think that heavier recoil springs are harder on slide stops (i.e., don't protect them, but may help damage them): more force is being pushed into the stop when the slide is returned than otherwise would be the case.

The part of this discussion that eludes me -- which is why I think we need someone who understand physics better than we do -- is the difference between NO RECOIL SPRING and a very, very heavy one.

What neither of you have explained is why a  heavier recoil spring -- which still allows the gun to cycle -- and which, in theory (at least) stores more of the force for the slide's return causes more FELT RECOIL.  

Doesn't the fact that more force is stored and returned with the forward movement of the slide an indication that LESS recoil must be passed to the hand during the rearward movement of the slide?  

I think we're all struggling with the same issue, but none of the explanations seem quite satisfactory, to me.

[Rod Slinger]

Walt......you and JWC007 both have expounded on a topic that I hope new shooter are paying attention to.  
Let me be clear that I can find NO fault with your previous post and this one.  

What may be tripping us up is the fact that there are two types of recoil.    Perceived recoil and actual recoil (my terms ).  
When you find someone who understands physics they will be working with actual recoil and will most likely tell us that the force used to launch a bullet will exert an equal rearward force on the launch platform ( the gun) and this will be unchanged by cycling of the firearm.  I base this on my 9 hrs. of college physics, for from an expert.  
To a shooter this is mostly worthless information.   What is important is perceived recoil.  I most strongly agree with you that the stronger the recoil spring the less perceived recoil,provided the gun cycles.  

I agree that stronger recoil springs put more wear and tar on slide stops.  New shooters take notice.  You should not drop the slide with the slide stop on an empty chamber.  Even a worse idea if you are running a stronger recoil spring.  

to quote  Russ Potterfield   "I love this stuff"   R S