TargetTalk

Sounds like marketing nonsense. Unless they've changed something major, it's a plain blowback design. The only delay is that the slide is heavy enough so there's some inertia to overcome before it gets moving, just like a lot of other .22's. Hardly revolutionary...

David Levene wrote: ↑Fri Jul 30, 2021 12:07 pm I suspect that you already know the answer David. It's the one that gives the athlete the feeling they prefer.

The best feel is the Match Gun, but unreliable as hell....

fc60 wrote: ↑Fri Jul 30, 2021 12:22 pm
The Pardini 22 Rapid Fire barrel has a different chamber than the Pardini SP.

It is cut to reduce the velocity of the bullet to just above the minimum required by ISSF.

The Rapid Fire barrels are not as accurate as the SP barrels at 50 yards.

Yes, the bolt is different on the RF model (lighter in weight) and perhaps some other features, as well.

A lot of shooters get caught out with the sloppy chamber and the chronograph.
If you use some ammo makers 250m/s ammo (soft) in a Pardini it will fail chronograph.
Example RWS P25 Rapid Fire is 260m/s in a 130mm barrel, Pardini 120mm.

Also other pistols like the Morini rapidfire or Tesro have reduced slide weight.
The Tesro also has a very short barrel (113mm).

So is it just the barrel weights.......I don't know ?

Gwhite wrote: ↑Fri Jul 30, 2021 5:59 pm Sounds like marketing nonsense.

You mean this marketing nonsense (quoting PardiniUSA): "Available also the “rapid fire” version SP RF on which important elaborate changes have been made to the bolt and barrel. Delivered with 6 Tungsten weights. LINK: https://www.pardiniguns.com/sp-sp-rf/ "

So is the "delayed-blow-back" as simple as bolt-cycle time dampened by increased MASS, or is there some other magic of physics at work here? Perhaps Issac Newton and Lord Daniel Bernoulli should just have a duel: SP vs RF.

atomicgale wrote: ↑Fri Jul 30, 2021 5:08 pm
Would someone please scientifically explain "Delayed blow-back" to me? No one has ever properly articulated this.

Delayed blow-back is typically found on higher power pistols .9mm etc
Two pistol systems exist
1/ Blowback - uses slide mass and chamber pressure to counter gas pressure. Typical rimfire.
2/ Locked barrel - uses a locking system to lock the breech to gas pressure. Either operated by
mechanical (recoil drop/lock.ie 1911) or gas operated (ie. Desert Eagle).
Delayed blow back may use a semi locking system (usually ball in dimple) to delay operation.
ie. Korth PRS roller-delayed blowback
Some rimfire firearms use a modified chamber shape to delay the release of the case wall.
Either a wave, taper of groove.
Some old 9mm had a grooved chamber that delayed blow back very well but reshaped the
cases so much that they could not be sized and nor reloaded.

David M wrote: ↑Fri Jul 30, 2021 6:41 pm

atomicgale wrote: ↑Fri Jul 30, 2021 5:08 pm
Would someone please scientifically explain "Delayed blow-back" to me? No one has ever properly articulated this.

SNIP
Delayed blow back may use a semi locking system (usually ball in dimple) to delay operation.
ie. Korth PRS roller-delayed blowback
Some rimfire firearms use a modified chamber shape to delay the release of the case wall.
Either a wave, taper of groove.
Some old 9mm had a grooved chamber that delayed blow back very well but reshaped the
cases so much that they could not be sized and nor reloaded.

I'm going to throw out another very popular delayed blowback system: Gas delayed blowback. The most popular pistol with this system is the H&K P7. Gas is vented from just in front of the chamber into a gas cylinder that acts on a piston retarding the movement of the slide.

I have a target gun with delayed blowback, the Colt 1911 .38 special mid-range wadcutter. It uses a shallow, wide grooved threading in the chamber to holds on to the case when it is under pressure. The barrel slides backward with the slide for about 5mm. By the time it reaches the end of travel the pressure has dropped and the case isn't gripped by the chamber and it extracted and ejected as normal. The chamber grooves are shallow enough that no damage is done to the case and it is easily reloadable.

" Korth PRS roller-delayed blowback"

I have one of these. Not only is it an exquisitely manufactured gun, it has the best trigger of all my handguns (a lot)

Must be something “special” about the RF pistol as it commands a A$400+ premium over the SP here in Oz. Part of this could be the tungsten weights it comes with as standard (as opposed to steel). As mentioned by Dave (fc60) the chamber is supposedly cut differently to reduce bullet velocity (and the slide is lightened). I believe that the reduced velocity is achieved by the rifling starting further from the chamber so that some of the propellant gas can escape past the bullet before the bullet engages the rifling. The alternative to porting the barrel (now outlawed since 2004). I guess the cost differential also comes down to reduced volume of demand.

Bob

Pardinis, like most .22lr, are simple blowback, not delayed blowback.
Delayed blowback means there is a delay between the cartridge firing and the breach starting to open.

Otherwise
https://en.wikipedia.org/wiki/Blowback_(firearms)

From limited testing it appears the barrel and slide of the SP vs RF both have an effect, but mostly its the barrel.
Could be my two barrels are randomly slightly different.

Looking at powder blast inside the slide of the RF it seems there's a lot more pressure in the barrel when the RF opens compared with the SP

The extra cost I guess is the niche identity, cost of the tungsten weights, extra machining on the slide.
Apparently the triggers are set differently at the factory, RF has a shorter trigger travel and less sear engagement.

It all seems to be a bit pointless as a lot of pistol match ammo won't make min velocity from a Pardini RF.
For me SK PM fails velocity in a RF, PM+ just about squeaks in
In an SP PM just about squeaks in

If I get the chance I may put an SP barrel in my RF, or turn up one myself and play with the chamber.

You can add a tiny amount of velocity by using the recoilspring of a centerfirepistol.