Continuing where we left off, in the 16th step, continue darwing the stock until you reach a point, where the trigger is supposed to be
Step 17: Add the trigger.
Step 18: Finish the shape by adding the stock. After that, make the magazine and the magazine release.
Step 19: On the side of the stock, add some details.
Step 20: Add bayonet to the weapon.
Step 21: Give the weapon a lick of paint to make it look fresh.
Step 22: If you want to, add some details on the weapon.
like drawing the safety
or smoothening up the front part of the gas cylinder.
That's all folks.