lol what pin?
the bolt catch on the we scar are just 2 pieces of metal + a little spring.
Its a simple design and it looks normal...
I actually think it is the cool down effect that doesnt make the bolt go far enough back to make the boltcatch work...
I am currently shooting at my attic and its winter here in Belgium
I guess its around 15 °C or even less...(thats 59 ° Fahrenheit)
So gonna try first thing tomorrow with some CO2