You grasp the forend at the front tip and pry it off. It is held in place by spring tension.
The model 5100 Stevens shotgun has a plastic stock
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Remove buttplate. Use a socket extension and rachet to unscrew the stock bolt (it's in that hole in the center of the butt)
Impossible to answer on the internet without detailed pictures.
Boyd's stocks on the net.
Try e-gunparts.com
To take apart a Stevens Model 311 double barrel for stock replacement, first ensure the shotgun is unloaded and the safety is engaged. Remove the forend by pushing the release lever and sliding it off the barrel. Next, locate the stock screw at the rear of the receiver, unscrew it using an appropriate screwdriver, and then gently pull the stock away from the receiver to detach it. Be cautious to avoid damaging any internal components during this process.
To field strip a Stevens Savage 12-gauge shotgun, first ensure the firearm is unloaded by checking the chamber and magazine. Next, remove the barrel by locating the barrel release button or lever, typically located near the forend. Once the barrel is detached, you can further disassemble the forend and stock if necessary, following the manufacturer’s instructions for any additional steps. Always refer to the owner’s manual for specific details related to your model.
To disassemble an Iver Johnson .410 shotgun, first ensure the firearm is unloaded. Open the action and remove the forend by pushing the release button, which is typically located on the underside of the forend. Next, unscrew the barrel from the receiver using the barrel nut, and then you can separate the stock from the receiver by removing the stock screw. Always consult the specific model's manual for detailed instructions and safety precautions.
The gun was built by Savage/Stevens for Sears, and is basically the Model 311. There were several different types of forend used on this model. We can probably supply the part, need to know if you require only the wood or the entire assembly including the forend iron. repair@countrygunsmith.net
If the owner's manual doesn't have instructions, seek out a qualified gun smith.
I bought one about seven years ago, synthetic stock and forend, for $125.