there should be a tab or button, behind the feeding hole. tap the mag against a hard surface to loosen the cap(or throw it across the street), and you can unscrew other cap inside remove the spring and there you go.
Airsoft PMAG/EMAG how to unjam
Those are not Magpul PTS Mid Cap mags.
If you have Magpul PTS Mid Cap mags, first start by removing the plate on the bottom of the mag. This is done by pushing in the button and sliding the plate to the front.
Once the plate is remove, you will see a small allen key screw. Remove this screw. Then hold the mag in one hand, and push the guts out of the shell with your other hand.
Once you have the core removed, on one side you will see a long skinny rectangle. Using a small flat blade screwdriver, pry this rectangle up in the CENTER of the rectangle. This will cause it to bow, and pop out of the core. Now pull the rectangle spring guide out along with the spring.
You can now clean your mag partially by blowing compressed air through the spring guide hole, which will blow most, if not all, dirt/sand through the mag and out the top. Or you can split the core by removing all screws and clean the mag with a cloth. Be careful you don't loose the small spring and bb catch at the top or the small nut at the bottom of the mag. (if you don't split the core, you won't have to worry about this) I don't recommend splitting the core if you are not good at putting things together. Proceed at your own risk.
