Best to seek the help of a gunsmith if you don't have a manual
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Steps:
1) Clear the weapon (make sure no rounds are in it)
2) Remove the magazine
3) Pull down on the trigger guard
4) Pull the slide back (with the trigger guard down)
5) Lift the back of slide up (when it's in the full back position)
6) Slide forward and it is apart.
Revers the steps to re-assemble. This is a lot like the Walther PP's that it was a rip-off / clone of.
The value of a PK22 American Arms pistol typically ranges from $150 to $300, depending on its condition, age, and whether it includes original packaging or accessories. Factors such as collector interest and regional demand can also influence the price. For an accurate valuation, it's best to consult recent sales data or a firearm appraisal expert.
Numrich (gunpartscorp) has them on their website for about $35.