I Have always had a passion for the props that used real fire arms underneath but they add furniture to the guns to sexy them up or change the look of the original gun..
A few that come to mind is the Robocop gun that was a Berretta underneath
strarship troopers Marita rifle that was a full auto mini 14 underneath
The rifle in starship troopers 3 was an AK-47
Aliens had the Pulse rifle and Smart gun... Thompson and mg-42
And my personal favorite The ape rifle in the Planet of the Apes that used the M1 Carbine. (damn dirty apes).
It would prove fun to get actual shooters out of thes props, but for many the extra furniture would stand up to the force of a real round.
I do know that the force of the blanks shattered the wood bodies of the rifles made for the 1st planet of the apes movie. And it messed up the schedule so bad repairing them that when they made the props for the 2nd movie The bodies were made of cast metal...