Was considering one of these as they have a threaded muzzle. My PPK-L is too valuable to molest. However, I'm not finding reviews of the Umarex rimfires after they've been used a while. I've heard they are made from die cast zinc? Can you go into detail with your experiences with yours, please?
Sure...
I have over 2000 rounds through mine and it's generally not picky about ammo. The only semi-auto .22 I have that is less picky is my Beretta Model 71. (which given that the current Israeli surplus Model 71s come pre-threaded, would be my first choice for a suppressed pistol given that it's already threaded although the PPKS come in a close second as its also easily adapted to a suppressor with the use of a readily available threaded barrel nut:
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The PPK/S .22 LR uses Zamak alloy in the frame and slide and this is a zinc alloy.
Detractors call it "pot metal" but there's a critical difference. Pot metal isn't all that dimensionally stable and cracks over time, but that's due to the high level of impurities in pot metal.
Zamak, and in particular the Zamak alloys used in firearms have a very high degree of purity and won't warp or crack over time.
As an example, the Ithaca Model 49 and 72 lever action .22 rifles made in the 1960s and 1970s were made with a Zamak alloy frame, and you'll still find them in use today.
Similarly, the Henry lever action .22 is very popular now and it has a large number of fans who swear by its utility and durability. But guess what? It's just a slightly rewarmed version of the Ithaca Model 72 lever action complete with Zamak alloy frame (with a cosmetic metal receiver cover).
There are also people who claim the PPK/S .22 LR is not a PPK/S at all but rather a P22 in PPK/S clothing. That's not true either. The only resemblance to the P22 is the use of a barrel liner with a barrel nut on the end to retain it.
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Let's compare my L66A1 version of the Walther PP in .22 LR with the PPK/S .22 LR:
Removing the slide shows the general PP layout. You'll notice that the PPK/S .22 LR uses a steel barrel shroud which includes the chamber face, an area where Zamak alloy would not wear as well. The barrel shroud has a P22 style barrel liner through it, with the barrel nut holding it in tension, but the shroud itself is retained in the frame just like the barrel in the PP or in a PPK/S.
In both pistols the .22 LR cartridge requires a lighter slide. That's done in the PP by thinning the sides of the steel slide, and in the PPK/S .22LR it's done by using Zamak alloy. The slides of the two are otherwise very similar.
The lockwork is clearly PP series and while you'll see minor differences in execution and the lack of some refinements like a loaded chamber indicator, it is still clearly a PP series pistol.
The small parts show a little less attention to detail in finish, compared to a PP, but that's understandable at the price point, and in terms of function, mine has held up just fine for welder 2000 rounds. You'll note here that they've created a cover of the normal open space under the grip, in order to add weight to the frame and keep it closer to the PPK/S in over all feel.
The magazine design on the PPK/S is vastly superior to the PP's .22 LR magazine. Any one who has owned a PP in .22 LR will tell you that it's really an 8 round magazine and isn't reliable with more than 8 loaded in it. In contrast the PPK/S .22 LR is an honest 120 round .22 pistol. The trade off is a longer magazine however and you won't have the option of a flush floor plate - at least in a factory magazine (there are a couple people who'll modify them).
The new magazine is also more reliable as it lets the cartridges splay a little farther, and the angle of the rounds is greater so that rim lock is not as big an issue. The magazines are also readily available and don't cost $110-$125 each like a PP magazine in .22 LR.
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As noted before, my PPK/S .22LR is just as reliable as my PP, but with 10 rounds rather than 8. It's just as accurate, and it's not as ammo sensitive as my PP.
Now...will it ever be an heirloom or collectors item? Probably not any more so than an Ithaca 72 or a Henry .22 LR. But it is none the less a very fun little pistol to shoot that has held up to well over 2000 rounds so far with no significant wear.
And for the money it's hard to beat as they seem to be going out the door now for around $300-$325. That's less than half of what you'd pay for a PP in .22 LR, but it's about the same as what the rapidly drying up Beretta Model 71 pistols are selling for at the moment.