I bought the Pierce +1 extensions for my two mags, installed them. Took them to the range loaded 7 rounds in each, fired and repeated 6 times with no issues. Bought two more mags and two more Pierce +1 extensions. Yesterday we took all four mags to the range and fired over 100 rounds, again no issues. I like the size of the +1's because they didn't appear any longer than the factory extended mag. They fit my hand perfectly.