[ARCHIVED THREAD] - Keltec has lost their mind: PR57 5,7 front lock breech top stripper clip feed defensive pistol (Page 9 of 9)
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Quoted: Is the case coating really necessary in this application? I thought it was only needed to function in P90 magazines because of the perpendicular orientation. You'll get varied reports of cases with the lube tumbled off functioning in the Rock or FiveseveN. Some say they work fine while others say it chokes. I've never tried it with my handloads, but probably will in the future as I have a growing stock of 3x fired cases that will be discarded after the next firing. |
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Quoted: Bah. What fun is that? Quoted: Quoted: Quoted: But can we suppress it? no, the KT rep in at least one vid was very clear about that Bah. What fun is that? It can't be suppressed w/ a conventional mount. You'll need an arm mounted to the Picatinny rail to mount the can to. |
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Quoted: you are correct, it the Five-seveN (and Rock/Ruger 57) is lever-delayed blowback. I'm not sure how much the lever actually does to delay anything but they are not direct blowback actions. Quoted: Quoted: Quoted: Quoted: Quoted: Is the case coating really necessary in this application? I thought it was only needed to function in P90 magazines because of the perpendicular orientation. I thought the lubrication was because the P90 is blowback, and the FiveseveN is done kind of retarded-blowback. This new pistol is short-recoil. The P90 & 57 pistol - along w/ the Rock, Ruger 57, and KelTec PMR30 .22 WMR pistols all share the same basic mechanism. Straight blowback, but the barrel travels with the bolt for a short distance before the case extracts from the chamber, allowing gas pressure to decrease and the case walls to relax off the chamber walls. Much less common in the carbines, where a heavier bolt can simply delay full opening for longer. Smith & KelTec have opted for recoil locked breach operation in their pistols. I used to own an FN FiveseveN. I thought it was done kind of lever-retarded blowback - not unlike a FAMAS. Is my memory bad? I sold it years ago. And isn't the S&W gas-operated, with a rotary-locking barrel? you are correct, it the Five-seveN (and Rock/Ruger 57) is lever-delayed blowback. I'm not sure how much the lever actually does to delay anything but they are not direct blowback actions. My bad - I had thought it was a simple moving barrel straight blowback. Now that I'm looking for it I can see the lever in the Ruger 57 video here: https://www.ruger.com/products/ruger57/models.html I'm not seeing how it acts on the slide, but presumably it's a lever-delayed blowback. |
Here's the FN57: How a FN Five-seven works | World of Guns Similar lever under the barrel as the Ruger, unsurprisingly. I'm not seeing how the lever works on the slide to accelerate it, however. It just appears to be there to return the barrel to battery. Coming to think about it, the bolt would need to be separate from the slide in a lever delayed blowback action, which I'm not seeing at all. This shows pretty clearly the FN57 isn't a lever-delayed blowback:  3D Animation: How the Unconventional FN Five-seveN Pistol Works Wikipedia claims it's a delayed blowback & references an FN patent claiming so, but I'm not seeing any interaction between the lever & the slide, simply spring pressure against the barrel through the lever. That's just complicated straight blowback, no matter what you call it. |
Ok, here's a video showing the cam working - about halfway through: How the FN Five-seven works 3D animation | with commentary | REMAKE So - the cam is controlling the relative speed of the barrel & slide, which is the same thing Ruger is referencing in their description. I'm not sure that amounts to delayed blowback, no matter what the Belgian patent office has to say - or the US. According to this post on Glocktalk, this might be a locked breech recoil system w/ a tilting locking block, al la Walther P-38/Beretta 92, just unlocking earlier: https://www.glocktalk.com/threads/the-blowback-fiveseven.1754632/ |
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It's not lever-delayed blowback for sure. They're using a "floating barrel" like the Kel-Tec PMR-30. This is done to give time for the relatively long, thin casing to "let go" of the chamber walls. But it looks like they've linked barrel motion with slide motion via that lever, which would mean it's not really straight blowback either. ETA: the more I look at it the more I think it's closest relative would be the Beretta / P38 locking system. |
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Quoted: It can't be suppressed w/ a conventional mount. You'll need an arm mounted to the Picatinny rail to mount the can to. Quoted: Quoted: Quoted: Quoted: But can we suppress it? no, the KT rep in at least one vid was very clear about that Bah. What fun is that? It can't be suppressed w/ a conventional mount. You'll need an arm mounted to the Picatinny rail to mount the can to. Doesn't really matter why. I have a lot less use for semi auto pistols or rifles at this point if I can't suppress them. 
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| I'm kind of surprised KT didn't add some ability to have a magazine cutoff so that one could more easily clear a jam. I'm still more curious on how both the Sub 2000 and the PR57 handle ammo that's warmer than the weak SS197SR and AE TMJ. Their P50 design barely handles SS198 with obviously signs of stretching the case vs blowing out the neck and primer pressure signs. I've stopped using the P50 for anything other than range plinking because of that. Hopefully with the Sub2k, and the PR57 they did some better homework. |
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Quoted: I'm kind of surprised KT didn't add some ability to have a magazine cutoff so that one could more easily clear a jam. I'm still more curious on how both the Sub 2000 and the PR57 handle ammo that's warmer than the weak SS197SR and AE TMJ. Their P50 design barely handles SS198 with obviously signs of stretching the case vs blowing out the neck and primer pressure signs. I've stopped using the P50 for anything other than range plinking because of that. Hopefully with the Sub2k, and the PR57 they did some better homework. I would hope that the locked action would make it more resistant to pressure-related issues, but we won't know until they get into the hands of people who will really put them through their paces. |
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Quoted: Here's the FN57:  https://www.youtube.com/watch?v=u_sIYUMxATESimilar lever under the barrel as the Ruger, unsurprisingly. I'm not seeing how the lever works on the slide to accelerate it, however. It just appears to be there to return the barrel to battery. Coming to think about it, the bolt would need to be separate from the slide in a lever delayed blowback action, which I'm not seeing at all. This shows pretty clearly the FN57 isn't a lever-delayed blowback: https://www.youtube.com/watch?v=NfSPCg3HL20Wikipedia claims it's a delayed blowback & references an FN patent claiming so, but I'm not seeing any interaction between the lever & the slide, simply spring pressure against the barrel through the lever. That's just complicated straight blowback, no matter what you call it. It's a decelerator, not an accelerator - I think. It regulates the velocity at which the slide is permitted to separate from the barrel. I'm not aware of any pistol that uses any kind of accelerator mechanism. |
[ARCHIVED THREAD] - Keltec has lost their mind: PR57 5,7 front lock breech top stripper clip feed defensive pistol (Page 9 of 9)
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