Gets stuck, breaks magazines - Magpump AR-15 Pro Magazine Loader

Should be simple to use, right? Well you use the lever and not sure if rounds are going in or not. Sometimes a few rounds go into the magazine, then the lever becomes stuck or very tight, then you realize it has tried to cram 3 rounds side by side into the mag, creating small cracks on the top of the magazine shell. Broke one mag because of this product. Never again.