I've had the exact same experience with my new Z-5RS's SB Brace, from my brief research (googling) it is a very common symptom of SB's products regardless of platform, which i can confirm by saying when i installed my HK A3 stock onto it the problem dissapeared and i can push the pins out by hand no problem.Happy and unhappy with my new Z5-RS. Unhappy = poor finishing on the receiver. What should be dimples look like craters. The SB brace fits so tight I need a rubber mallet to get it off and the push pin needs a hammer and punch if anyone has a cure for this let me know. Happy = functions great even with wobbly mags of various makes. Ran 300 rounds of Winchester 124gr Nato thru it now it functions with anything. Mounted a Sig Romeo 4S on it, zero it at 10,15 and 25 yds, hitting 6 inch round plates consistently at 50 yds.