Gil says '............My ten P's worth, I believe it is caused by the lack of gas inertia to overcome the initial unlocking of the bolt toggle from the locking shoulder. It is a problem that all L1A1 straight pull variants have, M14icon’s and AR10’s suffer from it too, as they are a compromise and are simply not working as the original gas operated designers intended them to......'
The fact that there is no 'gas inertia' is irrelevant SP rifles simply because, by default, there is no gas inertia! There CANNOT be! So there is nothing to assist the opening of the breech because it is positively locked. That is mechanical safety. And even if there WAS gas, as on an L1A1, the breech CANNOT be unlocked until the gas in the barrel is down to atmospheric pressure. Let's wait and see what Gils video shows us about how the BB is locked by the BBC