Skeptical about px4 rotary barrel

[Carcassonne]

I'm no rocket scientist but I've taken college physics and based one my understanding of how handguns work recoil is caused by the slide spring bunching up and the slide hitting the end of its cycle. If this is true then how does a rotating barrel dissipate recoil if the barrel has nothing to do with rearward forces?

Why wouldn't the barrel have anything to do with rearward forces? Think of the barrel as a rotating bolt with a rifled hole through the center. The force/energy needed to rotate the barrel is taken from the slide's rearward motion/recoil.



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[OCEquestrian]

The PX4 9mm I had was the lightest recoiling 9mm I've ever owned. The difference was subtle enough that I didn't notice it until the end of the day, when I picked up my Beretta 92fs and fired it. The recoil reduction is minor, and you will never be fooled into thinking its a 22.



My best guess as to how the recoil is reduced falls down to:

No vertical movement of any parts (except magazine stack). Even in a 92fs, the locking block (small as it is), is still slamming up and down. At the speeds the slide cycles at, that bit of mass starts proving some serious force. Even more so in a Browning tilting barrel.

I'd surmise there is some amount of counter-inertial force from forcing the bullet to rotate.Just like spinning a top takes some energy to get really fast, so does a bullet. While a 9mm isn't all that heavy or large, it still has some mass, some cross-sectional area, and some velocity. Enough that my bad math shows around 80,000 RPM (for a Glock 17 firing a bullet at 1100fps with a 1:9.84 twist rate). That being said, the contribution of this is likely minimal, but when added to the recoil force of the propellant, slide, etc, it might add up to be something (or be the straw that broke the proverbial camel's back). If the rotating barrel has been designed to ameliorate this twisting inertia, then it may somewhat balance out this twisting force. It really only needs to take the edge off of the twisting counter-force for the first 1-2" of travel, when pressure is highest).


So that's my hearsay. It may be wrong.

EDIT: more mental math. The rotational inertia thing is going to be very, very, very small. Less than 1/100th of a pound-inch.

Dont forget the torque that is produced as the bullet is sized down to grab the lands and grooves of the barrel's rifling...

[teflondog]

Some of the recoil is expended by using that energy to rotate the barrel. I doubt it makes a noticeable difference.

[semilin]

Some of the recoil is expended by using that energy to rotate the barrel. I doubt it makes a noticeable difference.

May or may not. The recoil force being redirected to rotate the barrel is one part, the other part is the force distribution is different as the barrel rotation will cause the frame rotation (potentially) in reverse direction, and the force is distributed not only on the rear part of the grip but also the side of the grip. Therefore, the feel of recoil is quite different from these tilt barrel pistols.

[aspenvalley]

For actual recoil to be reduced, kinetic energy has to be converted to heat. If the rotating barrel action has more drag or friction then it would have less recoil. Basic law of conservation of energy...

All the other points called here go to felt recoil not total energy pushed into your hand.

The only other theory is if the rotating barrel unlocks at a higher chamber pressure (earlier), less energy would be imparted to the slided as it would be vented out of the ejection port.

[Vicissitude]

Let's take an unrealistic scenario, you are in space, a bullet is inserted into nothing but a barrel and a magical firing pin fires the bullet. Because of Newtonian physics the bullet leaves the front of the barrel and the shell leaves the back of the barrel with the exact same kinetic energy. What happens to the barrel? In this Newtonian situation nothing happens to it. Now if there is a Block holding the shell flush with the barrel, the block will absorb the kinetic energy from the shell and want to move backwards. So for any translation of energy to a different direction other than backwards (Which is for the most part what we call recoil) the block holding the bullet flush would have to rotate ( Its called an action, right?), sort of how the vectors action goes downward, but in this case it would rotate, which I'm not convinced would do much for recoil anyways.

[aspenvalley]

Let's take an unrealistic scenario, you are in space, a bullet is inserted into nothing but a barrel and a magical firing pin fires the bullet. Because of Newtonian physics the bullet leaves the front of the barrel and the shell leaves the back of the barrel with the exact same kinetic energy. What happens to the barrel? In this Newtonian situation nothing happens to it. Now if there is a Block holding the shell flush with the barrel, the block will absorb the kinetic energy from the shell and want to move backwards. So for any translation of energy to a different direction other than backwards (Which is for the most part what we call recoil) the block holding the bullet flush would have to rotate ( Its called an action, right?), sort of how the vectors action goes downward, but in this case it would rotate, which I'm not convinced would do much for recoil anyways.

Your scenario requires that the powder burns instantly and transfer all of its energy instantaneously to the case and bullet. That is not how it happens. That is the whole point of a locked action. It gives the powder time to burn, and keep burning and expanding as the bullet travels down the barrel, once the bullet exists and pressure drops the action unlocks. Once the pressure has dropped how the action unlocks really does not matter outside of the friction of the system

[Lonestargrizzly]

PX4 recoil feels different than other pistols.
Almost like its recoiling straight back instead of back and up
I mean heck, glock adopted the same type of system for the G46.

[Mr. Beretta]

Hey...it works great.

What else do you need to know?

[BrassCase]

Another Full Size PX-4 in 40 SW owner here, I have a CZ 75B-SA in 40 which is a much heavier steel gun. The PX-4 is easier to shoot. The worst I can say about it is that the curve of the trigger is a little tight for me. The barrel rotates during recoil which uses up some of the recoil energy which is what softens the recoil. It slows down the slide since the travel path becomes effectively longer due to the twist on the barrel.

[Vicissitude]

Your scenario requires that the powder burns instantly and transfer all of its energy instantaneously to the case and bullet. That is not how it happens. That is the whole point of a locked action. It gives the powder time to burn, and keep burning and expanding as the bullet travels down the barrel, once the bullet exists and pressure drops the action unlocks. Once the pressure has dropped how the action unlocks really does not matter outside of the friction of the system

You are correct, after doing some research what i am describing is more of a blowback design whereas most modern handguns use the short recoil operation where the bolt locks into the barrel, momentarily creating a single piece while the round is ignited. If the barrel and bolt are physically linked together then both the barrel and bolt are what carry the rearward force and when they separate the force is divided proportionally amongst them in relation to their mass. So rotating the barrel could definitely "diffuse" some of the recoil.

[beetle]

in case you are interested in where the rotating barrel concept came from -- history of the gun that almost beat out the colt to become the 1911.

https://www.calguns.net/calgunforum/showthread.php?t=658546

[Dnele928]

Wow, great insights into the mechanics of the PX4. Thoroughly enjoyed the contributions CGers. Many thanks.

[maidenrules29]

I don't really care how it works. All I know is that my 9mm Storm is the sweetest shooting gun I own. And I have a lot of guns.

Sent from my SAMSUNG-SM-J727A using Tapatalk

[aspenvalley]

The Savage 45 design was closer to a blowback than a PX4. And the PX4 is more like a 1911 as the delaying in the unlocking is the same, the time the slide and barrel stay locked together as they travel reward. How the unlock is the only difference between at 1911 and a PX4, conceptually.