I have a Walther PP in .22 l.r. made in Zella Mehlis that is one of the first rimfire versions made and have shot this gun extensively.../
/....Contrary to earlier posters, I do not consider Umarex a respected German company!.../
/...I have a firearm, or two, for every need and honestly have to say that Umarex products do not meet my expectations and quality standards.
I don't think any of us is making a statement that anything made by Umarex is going to meet the same standard as a pre-war Walther, or even a Manurhin made PP pistol. In fact, I noted the unlikely probability of a PPK/S .22 LR ever obtaining anything close to heirloom status.
On the other hand, if you priced one of the older (even a comparatively modern "older") Walther PP or PPK in .22LR you'll notice they sell for 2.5 to 5 times the new price of one of the more recent Umarex-Walther PPK/S .22 LR pistols. If you've priced magazines for the older pistols you know they usually sell for north of $100-120 US, and a pre-war magazine will cost something north of $200.
What most of us who own one of the Umarex-Walther PPK/S .22LR pistols are saying is that they shoot far better than you'd expect for the price. Those of us who have both will more than likely tell you that they shoot on par with the older Walther pistols in terms of performance, rather than aesthetics. Real world, the new pistols sell on line in the $250 to $340 price range, with pretty much any site selling them for less than $325 being out of stock. That's the new price, used they'll sell in the $175-$200 range.
Even at the "new" price, it's actually excellent bang for the buck for someone who wants a "shooter" rather than a collector piece.
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The Colt-Umarex M4 .22 LR is in a similar situation. It also takes an incredible amount of heat because of its use of zinc alloy and takes additional criticism due to the lack of compatibility with aftermarket AR-15 parts.
However, I bought the M4 Tactical version shortly after it was released based on the recommendation of an old school gunsmith/gun shop owner whose opinion I trusted. He also described it as serious bang for the buck and he was absolutely spot on with his assessment.
Yes, it does use Zamak in the bolt carrier, but from an engineering perspective it's a very appropriate use of the material. The design also allows for fine tuning of the rifle to the ammo, and the barrel nut/flash hider can also be used to tension the barrel to produce excellent accuracy. My Colt-Umarex M4 Tactical is every bit as reliable and more accurate than my CMMG dedicated .22LR AR-15.
I suspect that most of the reliability and accuracy complaints with the Colt-Umarex rifles come from shooters who buy one and then almost immediately disassemble the rifle and bolt carrier without understanding how it works, with the result that they never get the recoil spring correct for the ammo, or the barrel tension where it needs to be for accuracy.
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There is additional Zamak alloy firearm irony in the form of the Henry .22LR lever action rifles. They use a Zamak alloy receiver that is hidden under a steel or brass cover - almost identical to the Ithaca Model 49 and Model 72 lever actions, which used a painted aluminum cover over the zinc alloy receiver.
The irony is that the same folks who love their "pot metal" Henry .22s, are very often the same people who revile the "pot metal" Colt-Umarex M4 and the Umarex-Walther PPK/S.