Pros:
Powerful
Pin guided
Fairly easy to use/maintain
Looks "real"
Fairly relaible
Cons:
Mags can act funky
The charging handle has to be pulled quickly
Not very accurate
Bad Range = 15-25ft
Credits:
Puddock for his Kar98 stock and AK receiver.

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Maybe an rail system?
Other than that, I can't think of any