I use the PVC feeders too, but do mine a little different. The way I do it may help others who see their PVC feeders get stuck or choked up neat the bottom and the feed does not come out.
First I use 4 inch sewer grade as it is cheaper. On the bottom of the pipe, I put a small 90 degree bend. (use the small bend as they make too a small and a large). On the end of the bend, I put another small say about a 8 inch long 4 inch pipe then the cap on it. Now take a jig saw or something and cut an oval out of the top of the pipe about 5 inches in lenght.
After that is done, I use a screw to secure all the parts together to keep them from coming apart. Now fill the top with feed and let the chickens go at it. Make sure you put a cap over the feed to keep the water out. You will not have a problem with it choking at the bottom. The point of the oval, is to allow the chickens to stick their heads in and eat. If it does get clogged, the chickens will fix it as they want to eat. They will stick their head inside the pipe towards the back and start eating and when they do, it will break the clog. You will not have to worry about it.
Hope you understand what I am trying to say.