Guarder make a metal receiver (upper and lower) and silencer. I am not sure if the receiver fits the .177 version (I don't see why not but it is made for 6mm). The silencer does fit but is not cheap (but is substantial and well made), it look excellent.
Spare magazines are available for .177 but I have heard of and experienced problems with them, the seal that mates with the bolt sits about 1mm proud of the original and my 2011 Uzi will not cycle properly with the new magazines.
I hear that in .177 this has now been discontinued which is a real shame, it is well made and excellent fun to shoot.
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