Invisiblesoul has the right idea. Ensure you are hitting the pins from the correct direction, back up your rifle on a solid surface, use a nail punch that conforms to the curvature of the pins and give it a good wack! A section of 2X4 with a hole drilled in it for the pin to fall into is a good backing to rest your rifle on. Don’t try to tap the pins out on a table top or flexible work bench, your energy is being absorbed by the table tops flexing.
As far as the gas tube is concerned. Buy some penetrating oil and shoot a bit down the back of the FSB where the tube inserts. Take a pair of vice grips and wrap the jaws with electrical tape. Lightly clamp the vice grips to the gas tube with out crushing it. Now try to wiggle the tube out. If it still won’t budge a light tap with a hammer to the vice grips should do the trick.